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• 1. [Image] Investigation of Two Areas in New York State which may have Potential for Geothermal Energy. Progress Report, May 1, 1976--September 31, 1976

  	Significant results to date include the following: (1) the present Adirondack Mountains Dome is undergoing rapid contemporary vertical doming; the velocity at the center of the dome is 3.7mm/yr, compared ...
  	Citation × Citation Citation Abstract Copy Title: Investigation of Two Areas in New York State which may have Potential for Geothermal Energy. Progress Report, May 1, 1976--September 31, 1976 Author: Isachsen, Y.W. Year: 1976 Significant results to date include the following: (1) the present Adirondack Mountains Dome is undergoing rapid contemporary vertical doming; the velocity at the center of the dome is 3.7mm/yr, compared to 1mm/yr for the Swiss Alps; (2) post-Pleistocene fault offsets measuring from one to eleven millimeters have been found in the Adirondacks, indicating vertical uplift during the past 10,000 years; (3) the Panther Mountain Circular drainage feature is structurally-controlled and shows a 10 to 20 milligal negative Simple Bouguer gravity anomaly such as might be produced by a buried felsic pluton Title: Investigation of Two Areas in New York State which may have Potential for Geothermal Energy. Progress Report, May 1, 1976--September 31, 1976 Author: Isachsen, Y.W. Year: 1976 Significant results to date include the following: (1) the present Adirondack Mountains Dome is undergoing rapid contemporary vertical doming; the velocity at the center of the dome is 3.7mm/yr, compared to 1mm/yr for the Swiss Alps; (2) post-Pleistocene fault offsets measuring from one to eleven millimeters have been found in the Adirondacks, indicating vertical uplift during the past 10,000 years; (3) the Panther Mountain Circular drainage feature is structurally-controlled and shows a 10 to 20 milligal negative Simple Bouguer gravity anomaly such as might be produced by a buried felsic pluton Close

• 2. [Image] Stratigraphy and Alteration, 15 Shallow Thermal Gradient Holes, Roosevelt Hot Springs KGRA and Vicinity, Millard and Beaver Counties, Utah

  	Fifteen shallow thermal gradient drill holes were recently completed by Geothermal Power Corporation (GPCR) in the vicinity of the Roosevelt Hot Springs KGRA. Five holes penetrated Tertiary granitic rocks ...
  	Citation × Citation Citation Abstract Copy Title: Stratigraphy and Alteration, 15 Shallow Thermal Gradient Holes, Roosevelt Hot Springs KGRA and Vicinity, Millard and Beaver Counties, Utah Author: Hulen, J.B. Year: 1978 Fifteen shallow thermal gradient drill holes were recently completed by Geothermal Power Corporation (GPCR) in the vicinity of the Roosevelt Hot Springs KGRA. Five holes penetrated Tertiary granitic rocks and Precambrian gneiss east of the KGRA. Seven holes completed entirely in alluvium near the southwestern corner of the KGRA encountered a near-surface marker horizon of Pleistocene pumice and perlite. Maximum calculated alluvial sedimentation rates since initial deposition of this pumice and perlite range from 1 foot in 12,500 years to 1 foot in 2,300 years. Three holes east of the Mineral Mountains penetrated late Cenozoic basaltic andesite beneath a thin veneer of alluvium. All 15 GPCR drill holes appear to be peripheral to a central zone of anomalously high thermal gradient and low resisitivity delineated by previous investigations. GPCR-8 and -14, however, are characterized by high heat flow and relatively abundant manganese oxide mineralization, which may reflect a favorable hydrologic system controlling thermal fluid flow at depth. These holes thus seem most encouraging for discovery of a deeper high-temperature geothermal resource Title: Stratigraphy and Alteration, 15 Shallow Thermal Gradient Holes, Roosevelt Hot Springs KGRA and Vicinity, Millard and Beaver Counties, Utah Author: Hulen, J.B. Year: 1978 Fifteen shallow thermal gradient drill holes were recently completed by Geothermal Power Corporation (GPCR) in the vicinity of the Roosevelt Hot Springs KGRA. Five holes penetrated Tertiary granitic rocks and Precambrian gneiss east of the KGRA. Seven holes completed entirely in alluvium near the southwestern corner of the KGRA encountered a near-surface marker horizon of Pleistocene pumice and perlite. Maximum calculated alluvial sedimentation rates since initial deposition of this pumice and perlite range from 1 foot in 12,500 years to 1 foot in 2,300 years. Three holes east of the Mineral Mountains penetrated late Cenozoic basaltic andesite beneath a thin veneer of alluvium. All 15 GPCR drill holes appear to be peripheral to a central zone of anomalously high thermal gradient and low resisitivity delineated by previous investigations. GPCR-8 and -14, however, are characterized by high heat flow and relatively abundant manganese oxide mineralization, which may reflect a favorable hydrologic system controlling thermal fluid flow at depth. These holes thus seem most encouraging for discovery of a deeper high-temperature geothermal resource Close

• 3. [Image] A new model for the formation of Crater Lake Caldera, Oregon

  	ill. (some col.), maps ; Thesis (Ph. D.)--Oregon State University, 1972; Includes bibliographical references
  	Citation × Citation Citation Abstract Copy Title: A new model for the formation of Crater Lake Caldera, Oregon Author: Lidstrom, John Walter Year: 1972, 2008 ill. (some col.), maps ; Thesis (Ph. D.)--Oregon State University, 1972; Includes bibliographical references Title: A new model for the formation of Crater Lake Caldera, Oregon Author: Lidstrom, John Walter Year: 1972, 2008 ill. (some col.), maps ; Thesis (Ph. D.)--Oregon State University, 1972; Includes bibliographical references Close

• 4. [Image] The 1980-1982 Geothermal Resource Assessment Program in Washington

  	Since 1978, the Division of Geology and Earth Resources of the Washington Department of Natural Resources has participated in the U.S. Department of Energy's (USDOE) StateCoupled Geothermal Resource Program. ...
  	Citation × Citation Citation Abstract Copy Title: The 1980-1982 Geothermal Resource Assessment Program in Washington Author: Korosec, M. A. Year: 1983 Since 1978, the Division of Geology and Earth Resources of the Washington Department of Natural Resources has participated in the U.S. Department of Energy's (USDOE) StateCoupled Geothermal Resource Program. Federal and state funds have been used to investigate and evaluate the potential for geothermal resources, on both a reconnaissance and area-specific level. Preliminary results and progress reports for the period up through mid-1980 have already been released as a Division Open File Report (Korosec, Schuster, and others, 1981). Preliminary results and progress summaries of work carried out from mid-1980 through the end of 1982 are presented in this report Title: The 1980-1982 Geothermal Resource Assessment Program in Washington Author: Korosec, M. A. Year: 1983 Since 1978, the Division of Geology and Earth Resources of the Washington Department of Natural Resources has participated in the U.S. Department of Energy's (USDOE) StateCoupled Geothermal Resource Program. Federal and state funds have been used to investigate and evaluate the potential for geothermal resources, on both a reconnaissance and area-specific level. Preliminary results and progress reports for the period up through mid-1980 have already been released as a Division Open File Report (Korosec, Schuster, and others, 1981). Preliminary results and progress summaries of work carried out from mid-1980 through the end of 1982 are presented in this report Close

• 5. [Image] Petrographic Analysis and Correlation of Volcanic Rocks in Bostic 1-A Well near Mountain Home, Idaho

  	Detailed examination of volcanic rock cuttings from the Bostic I-A well near Mountain Home, Idaho, provides data that correlate the stratigraphy of the well with the regional stratigraphy of the western ...
  	Citation × Citation Citation Abstract Copy Title: Petrographic Analysis and Correlation of Volcanic Rocks in Bostic 1-A Well near Mountain Home, Idaho Author: Arney, B. H. Year: 1984 Detailed examination of volcanic rock cuttings from the Bostic I-A well near Mountain Home, Idaho, provides data that correlate the stratigraphy of the well with the regional stratigraphy of the western Snake River Plain. The Bostic I-A well penetrates basalt of the Middle Pleistocene Bruneau Formation and underlying sedimentary rocks of the Upper Pliocene Glenns Ferry Formation. Basalt underlying the Glenns Ferry Formation is most likely Banbury Basalt of Middle Pliocene age or Banbury equivalent. A 350-ft interval of felsic volcanics is then intersected above another 600 ft of basalt. The well bottoms in altered felsic volcanics Title: Petrographic Analysis and Correlation of Volcanic Rocks in Bostic 1-A Well near Mountain Home, Idaho Author: Arney, B. H. Year: 1984 Detailed examination of volcanic rock cuttings from the Bostic I-A well near Mountain Home, Idaho, provides data that correlate the stratigraphy of the well with the regional stratigraphy of the western Snake River Plain. The Bostic I-A well penetrates basalt of the Middle Pleistocene Bruneau Formation and underlying sedimentary rocks of the Upper Pliocene Glenns Ferry Formation. Basalt underlying the Glenns Ferry Formation is most likely Banbury Basalt of Middle Pliocene age or Banbury equivalent. A 350-ft interval of felsic volcanics is then intersected above another 600 ft of basalt. The well bottoms in altered felsic volcanics Close

• 6. [Image] Seeking refuge: making space for migratory waterfowl and wetlands along the Pacific Flyway

  	Abstract "Seeking Refuge" examines the history of migratory waterfowl management along the Pacific Flyway, the westernmost of four main migration routes in North America. Drawing on approaches from historical ...
  	Citation × Citation Citation Abstract Copy Title: Seeking refuge: making space for migratory waterfowl and wetlands along the Pacific Flyway Author: Wilson, Robert Michael Year: 2003, 2005, 2004 Abstract "Seeking Refuge" examines the history of migratory waterfowl management along the Pacific Flyway, the westernmost of four main migration routes in North America. Drawing on approaches from historical geography and environmental history, this study shows how wildlife officials developed migratory bird refuges in Oregon and California, where over 60 percent of Pacific Flyway waterfowl winter. During the early-twentieth century, reclamation and river diking eliminated most of the wetlands in the birds' wintering range. Bird enthusiasts such as bird watchers and duck hunters successfully lobbied for the creation of wildlife refuges in a few areas along the flyway. These early refuges failed to protect waterfowl habitat and they were severely degraded by reclamation. In the 1930s and 1940s, the U.S. Fish and Wildlife Service (FWS) and its predecessor, the Bureau of Biological Survey, undertook an ambitious program to resurrect these sanctuaries and to create new ones. Many farmers opposed these refuges out of fear that waterfowl would damage crops. To respond to these concerns and to ensure an adequate food supply for the birds, the FWS raised rice, barley, and other grains. The agency adopted many of the technologies of modern, industrial agriculture including synthetic herbicides and insecticides such as 2, 4-D and DDT. By the 1960s, the refuges had become largely mirrors of the surrounding irrigated farmlands, the main difference being that the FWS raised grain for waterfowl rather than for market. Refuges could not escape the agricultural settings in which they were embedded. As units within the irrigated countryside, Pacific Flyway refuges were often at the mercy of nearby farmers and federal reclamation agencies. Poor water quality and insufficient supplies of water often hampered FWS efforts to manage refuges. In the late-twentieth century, reduced water supply due to diversions to California municipalities and to sustain endangered fish species affected the amount of water reaching refuges. This dissertation has other goals. First, it critiques the anthropocentrism of most historical geography by focusing on how political, cultural, and ecological factors affected wildlife. Second, it contributes to the literature on the state's role in environmental protection by investigating the overlapping, and often contradictory, spaces within which wildlife managers implemented environmental regulations. Title: Seeking refuge: making space for migratory waterfowl and wetlands along the Pacific Flyway Author: Wilson, Robert Michael Year: 2003, 2005, 2004 Abstract "Seeking Refuge" examines the history of migratory waterfowl management along the Pacific Flyway, the westernmost of four main migration routes in North America. Drawing on approaches from historical geography and environmental history, this study shows how wildlife officials developed migratory bird refuges in Oregon and California, where over 60 percent of Pacific Flyway waterfowl winter. During the early-twentieth century, reclamation and river diking eliminated most of the wetlands in the birds' wintering range. Bird enthusiasts such as bird watchers and duck hunters successfully lobbied for the creation of wildlife refuges in a few areas along the flyway. These early refuges failed to protect waterfowl habitat and they were severely degraded by reclamation. In the 1930s and 1940s, the U.S. Fish and Wildlife Service (FWS) and its predecessor, the Bureau of Biological Survey, undertook an ambitious program to resurrect these sanctuaries and to create new ones. Many farmers opposed these refuges out of fear that waterfowl would damage crops. To respond to these concerns and to ensure an adequate food supply for the birds, the FWS raised rice, barley, and other grains. The agency adopted many of the technologies of modern, industrial agriculture including synthetic herbicides and insecticides such as 2, 4-D and DDT. By the 1960s, the refuges had become largely mirrors of the surrounding irrigated farmlands, the main difference being that the FWS raised grain for waterfowl rather than for market. Refuges could not escape the agricultural settings in which they were embedded. As units within the irrigated countryside, Pacific Flyway refuges were often at the mercy of nearby farmers and federal reclamation agencies. Poor water quality and insufficient supplies of water often hampered FWS efforts to manage refuges. In the late-twentieth century, reduced water supply due to diversions to California municipalities and to sustain endangered fish species affected the amount of water reaching refuges. This dissertation has other goals. First, it critiques the anthropocentrism of most historical geography by focusing on how political, cultural, and ecological factors affected wildlife. Second, it contributes to the literature on the state's role in environmental protection by investigating the overlapping, and often contradictory, spaces within which wildlife managers implemented environmental regulations. Close

• 7. [Image] Programmatic environmental assessment for Klamath Basin Ecosystem Restoration Office Projects, 2000-2010

  	Programmatic Environmental Assessment Summary This Environmental Assessment (EA) provides compliance with the National Environmental Policy Act (NEPA) for restoration actions undertaken by the US Fish ...
  	Citation × Citation Citation Abstract Copy Title: Programmatic environmental assessment for Klamath Basin Ecosystem Restoration Office Projects, 2000-2010 Author: U.S. Fish and Wildlife Service. Klamath Basin Ecosystem Restoration Office. Year: 2000, 2005, 2004 Programmatic Environmental Assessment Summary This Environmental Assessment (EA) provides compliance with the National Environmental Policy Act (NEPA) for restoration actions undertaken by the US Fish & Wildlife Service's Klamath Basin Ecosystem Restoration Office (ERO) in Klamath Falls, Oregon. These restoration activities are needed due to the large-scale loss of wetland and riparian habitat and degraded water quality. The purpose of these restoration efforts is the improvement of conditions of the watershed with specific regard to habitat and water quality, resulting in, among other benefits, improved conditions for the endangered fish species (bull trout and Lost River and shortnose sucker) populations of the basin. The geographic scope of this EA is defined as the upper Klamath River basin, including the entire watershed from Irongate Dam upstream to the headwaters. This EA is intended to provide NEPA compliance for restoration projects conducted between the years 2000 and 2010. The ERO was established in 1993 to sponsor and assist with a variety of restoration activities in the Klamath Basin. The ERO funds and provides technical assistance to restoration projects involving private landholders, concerned groups, and other state, federal, and tribal agencies. Four alternatives are presented in this EA. The proposed alternative (Alternative 1) consists of a comprehensive program of ecosystem restoration, promoting projects in both riparian areas and in upland habitats. This would continue the current program in effect since 1994. NEPA compliance would primarily be carried out via a single, programmatic document saving time and funds. The Fish & Wildlife Service proposes to fund and administer the following projects types: Riparian Projects: (fencing for livestock management; native plant establishment & diversification; non-native plant removal/control; erosion control; contour re-establishment; impoundment removal; wildlife habitat improvements) Wetland Projects: (fencing; wetland restoration and enhancement; wildlife habitat improvements) Upland or Road Projects: (road abandonment, decommissioning, & obliteration; road drainage improvements and storm proofing, re-establishment of historic contours; silvicultural treatments; native plant establishment/diversification; non-native plant removal/control; fencing; landslide treatments; culvert/stream crossing upgrades; erosion control; wildlife habitat improvements). In-stream Projects: (habitat complexity and diversity improvements; hydrologic regime improvements; coarse woody debris supplementation; natural or artificial barrier removal, modification &/or creation; fish screens installation). Alternative 2 would concentrate restoration efforts only on riparian, instream, and wetland areas. Road projects would be conducted only within the riparian corridor, as defined. NEPA compliance would also be conducted programmatically. Alternative 3 would cease all restoration activities conducted and funded by the ERO in the Klamath Basin. This alternative would serve as a benchmark against which the effects of the restoration alternatives discussed above can be compared. Alternative 4, the "No Action" alternative, would continue current management policies with regard to NEPA compliance, providing compliance on a project by project basis requiring independent analysis for each project. The affected environment of the region is described in detail. The environment has been changed significantly since the 1890's due to logging, agriculture and urban development. An extensive system of dams, canals, and drainage structures has resulted in the conversion of approximately 80% of pre-settlement wetlands to agricultural uses. Riparian corridors have been similarly impacted, and upland forests regions have been affected by logging, road construction and other factors. These changes have contributed to problems with the water quality in the region, contributing to the listing of several fish species as threatened or endangered; loss of habitat has affected a large number of other species as well. The environmental effects of each alternative is analyzed. Some short term negative impacts could occur as a result of the projects authorized by both Alternative 1 and Alternative 2, but these would be strongly offset by the expected beneficial results to water quality and habitat conditions. Alternative 1 would be expected to have a greater overall effect on the environment than Alternative 2, since many of the underlying factors with which restoration efforts are concerned originate in upland conditions (i.e. sedimentation and hydrologic functionality). Alternative 3 would result in conditions remaining much as they are currently, although other programs and organizations are making efforts at restoration activities. The environmental impacts of individual projects anticipated under Alternative 4 would be generally the same as for similar projects under Alternative 1. The primary difference between the two alternatives would be the higher efficiency and improved cumulative analysis resulting from a programmatic approach as proposed in Alternative 1. Public participation in the NEPA process has been, and will continue to be, solicited and welcomed. Compliance with state and federal laws and regulations such as the Clean Water Act, National Historic Preservation Act, and the Endangered Species Act, as well as guidelines for contaminant surveys, will be carried out as detailed. While these projects are expected to play an important role in the restoration of the region, none of these alternatives are expected to have a significant impact when compared with the loss of wetland, riparian and upland habitats over the past century, impacts which do occur would be of a cumulatively beneficial nature. Other restoration efforts are being carried out in the area by other governmental and private groups, and it is expected that these combined efforts will achieve important beneficial results for the ecosystem. Title: Programmatic environmental assessment for Klamath Basin Ecosystem Restoration Office Projects, 2000-2010 Author: U.S. Fish and Wildlife Service. Klamath Basin Ecosystem Restoration Office. Year: 2000, 2005, 2004 Programmatic Environmental Assessment Summary This Environmental Assessment (EA) provides compliance with the National Environmental Policy Act (NEPA) for restoration actions undertaken by the US Fish & Wildlife Service's Klamath Basin Ecosystem Restoration Office (ERO) in Klamath Falls, Oregon. These restoration activities are needed due to the large-scale loss of wetland and riparian habitat and degraded water quality. The purpose of these restoration efforts is the improvement of conditions of the watershed with specific regard to habitat and water quality, resulting in, among other benefits, improved conditions for the endangered fish species (bull trout and Lost River and shortnose sucker) populations of the basin. The geographic scope of this EA is defined as the upper Klamath River basin, including the entire watershed from Irongate Dam upstream to the headwaters. This EA is intended to provide NEPA compliance for restoration projects conducted between the years 2000 and 2010. The ERO was established in 1993 to sponsor and assist with a variety of restoration activities in the Klamath Basin. The ERO funds and provides technical assistance to restoration projects involving private landholders, concerned groups, and other state, federal, and tribal agencies. Four alternatives are presented in this EA. The proposed alternative (Alternative 1) consists of a comprehensive program of ecosystem restoration, promoting projects in both riparian areas and in upland habitats. This would continue the current program in effect since 1994. NEPA compliance would primarily be carried out via a single, programmatic document saving time and funds. The Fish & Wildlife Service proposes to fund and administer the following projects types: Riparian Projects: (fencing for livestock management; native plant establishment & diversification; non-native plant removal/control; erosion control; contour re-establishment; impoundment removal; wildlife habitat improvements) Wetland Projects: (fencing; wetland restoration and enhancement; wildlife habitat improvements) Upland or Road Projects: (road abandonment, decommissioning, & obliteration; road drainage improvements and storm proofing, re-establishment of historic contours; silvicultural treatments; native plant establishment/diversification; non-native plant removal/control; fencing; landslide treatments; culvert/stream crossing upgrades; erosion control; wildlife habitat improvements). In-stream Projects: (habitat complexity and diversity improvements; hydrologic regime improvements; coarse woody debris supplementation; natural or artificial barrier removal, modification &/or creation; fish screens installation). Alternative 2 would concentrate restoration efforts only on riparian, instream, and wetland areas. Road projects would be conducted only within the riparian corridor, as defined. NEPA compliance would also be conducted programmatically. Alternative 3 would cease all restoration activities conducted and funded by the ERO in the Klamath Basin. This alternative would serve as a benchmark against which the effects of the restoration alternatives discussed above can be compared. Alternative 4, the "No Action" alternative, would continue current management policies with regard to NEPA compliance, providing compliance on a project by project basis requiring independent analysis for each project. The affected environment of the region is described in detail. The environment has been changed significantly since the 1890's due to logging, agriculture and urban development. An extensive system of dams, canals, and drainage structures has resulted in the conversion of approximately 80% of pre-settlement wetlands to agricultural uses. Riparian corridors have been similarly impacted, and upland forests regions have been affected by logging, road construction and other factors. These changes have contributed to problems with the water quality in the region, contributing to the listing of several fish species as threatened or endangered; loss of habitat has affected a large number of other species as well. The environmental effects of each alternative is analyzed. Some short term negative impacts could occur as a result of the projects authorized by both Alternative 1 and Alternative 2, but these would be strongly offset by the expected beneficial results to water quality and habitat conditions. Alternative 1 would be expected to have a greater overall effect on the environment than Alternative 2, since many of the underlying factors with which restoration efforts are concerned originate in upland conditions (i.e. sedimentation and hydrologic functionality). Alternative 3 would result in conditions remaining much as they are currently, although other programs and organizations are making efforts at restoration activities. The environmental impacts of individual projects anticipated under Alternative 4 would be generally the same as for similar projects under Alternative 1. The primary difference between the two alternatives would be the higher efficiency and improved cumulative analysis resulting from a programmatic approach as proposed in Alternative 1. Public participation in the NEPA process has been, and will continue to be, solicited and welcomed. Compliance with state and federal laws and regulations such as the Clean Water Act, National Historic Preservation Act, and the Endangered Species Act, as well as guidelines for contaminant surveys, will be carried out as detailed. While these projects are expected to play an important role in the restoration of the region, none of these alternatives are expected to have a significant impact when compared with the loss of wetland, riparian and upland habitats over the past century, impacts which do occur would be of a cumulatively beneficial nature. Other restoration efforts are being carried out in the area by other governmental and private groups, and it is expected that these combined efforts will achieve important beneficial results for the ecosystem. Close

• 8. [Image] Draft upper Williamson River Watershed assessment

  	"Prepared for Klamath Basin Ecosystem Foundation, and the Upper Williamson River Catchment Group, in cooperation with the Upper Klamath Basin Working Group, and the Klamath Watershed Council."
  	Citation × Citation Citation Abstract Copy Title: Draft upper Williamson River Watershed assessment Author: David Evans and Associates, Inc. Year: 2004, 2005 "Prepared for Klamath Basin Ecosystem Foundation, and the Upper Williamson River Catchment Group, in cooperation with the Upper Klamath Basin Working Group, and the Klamath Watershed Council." Title: Draft upper Williamson River Watershed assessment Author: David Evans and Associates, Inc. Year: 2004, 2005 "Prepared for Klamath Basin Ecosystem Foundation, and the Upper Williamson River Catchment Group, in cooperation with the Upper Klamath Basin Working Group, and the Klamath Watershed Council." Close

• 9. [Image] Ground water hydrology of four proposed project areas in the Klamath Basin, Oregon

  	"OF-01-01"
  	Citation × Citation Citation Abstract Copy Title: Ground water hydrology of four proposed project areas in the Klamath Basin, Oregon Author: Oregon. Water Resources Dept Year: 2001, 2005 "OF-01-01" Title: Ground water hydrology of four proposed project areas in the Klamath Basin, Oregon Author: Oregon. Water Resources Dept Year: 2001, 2005 "OF-01-01" Close

• 10. [Image] Distribution and biology of suckers in Lower Klamath reservoirs : 1999 final report

  	Abstract The objectives of this two-year study (1998-1999) were to document distribution, abundance, age class structure, recruitment success, and habitat use by all life history stages of shortnose and ...
  	Citation × Citation Citation Abstract Copy Title: Distribution and biology of suckers in Lower Klamath reservoirs : 1999 final report Author: Desjardins, Marc; Markle, Douglas F. Year: 2000, 2005 Abstract The objectives of this two-year study (1998-1999) were to document distribution, abundance, age class structure, recruitment success, and habitat use by all life history stages of shortnose and Lost River suckers in three lower Klamath River hydroelectric reservoirs (J. C. Boyle, Copco, and Iron Gate). Lost River sucker catches were sporadic (only 3 adult individuals total) and the focus of our analyses, therefore, shifted to shortnose suckers. Adult and larval suckers were found in all reservoirs both years. All life history stages (larvae, juveniles and adults) were found in J. C. Boyle during both years and in Copco in 1999. Juvenile suckers were not found in Copco in 1998. The number of adult shortnose suckers was highest in Copco reservoir (n=165), followed by J.C. Boyle (n=50) and Iron Gate (n=22). Larger and older individuals dominated Copco and Iron Gate reservoirs and little size structure was detected. J. C. Boyle tended to have smaller adult shortnose suckers and many size classes were present. Unidentifiable larval suckers were most abundant in Copco reservoir where historic spawning of shortnose suckers has been documented. Larval suckers in Copco and Iron Gate reservoirs were most abundant in mid to late June before quickly disappearing from catches. J. C. Boyle larval suckers peaked in mid July, attained larger sizes, and were caught later in the season. It appeared that recruitment of young-of-the-year suckers only occurred in J. C. Boyle with downstream reservoirs recruiting older individuals, perhaps those that had earlier recruited to J. C. Boyle. Tagging studies could clarify adult recruitment dynamics and an additional study of juvenile recruitment would be needed to confirm these patterns. Predation pressure may be somewhat reduced in J. C. Boyle in comparison to the other reservoirs as its fish community was dominated by native fishes while communities in Copco and Iron Gate reservoirs were dominated by exotic predators. J. C. Boyle also possessed proportionally more littoral habitat, which suggests it may provide a more stable environment for young fishes. However, our sampling was inadequate to demonstrate such relationships due to high variance in larval and juvenile catches and potentially confounding habitat variables. One such variable was water level fluctuations, which could interact with habitat and resource availability in complex ways. For example, water level fluctuations, presumed to have a negative impact, were greatest in J. C. Boyle. Extrapolation from the literature suggests it should have had the poorest habitat for larval and juvenile suckers, but our results indicated J. C. Boyle had the most young suckers. Additional study of the relationships between water level fluctuations, habitat availability, the exotic fish community, and juvenile sucker recruitment would be needed to better understand early life history ecology of endangered lake suckers in these systems. Title: Distribution and biology of suckers in Lower Klamath reservoirs : 1999 final report Author: Desjardins, Marc; Markle, Douglas F. Year: 2000, 2005 Abstract The objectives of this two-year study (1998-1999) were to document distribution, abundance, age class structure, recruitment success, and habitat use by all life history stages of shortnose and Lost River suckers in three lower Klamath River hydroelectric reservoirs (J. C. Boyle, Copco, and Iron Gate). Lost River sucker catches were sporadic (only 3 adult individuals total) and the focus of our analyses, therefore, shifted to shortnose suckers. Adult and larval suckers were found in all reservoirs both years. All life history stages (larvae, juveniles and adults) were found in J. C. Boyle during both years and in Copco in 1999. Juvenile suckers were not found in Copco in 1998. The number of adult shortnose suckers was highest in Copco reservoir (n=165), followed by J.C. Boyle (n=50) and Iron Gate (n=22). Larger and older individuals dominated Copco and Iron Gate reservoirs and little size structure was detected. J. C. Boyle tended to have smaller adult shortnose suckers and many size classes were present. Unidentifiable larval suckers were most abundant in Copco reservoir where historic spawning of shortnose suckers has been documented. Larval suckers in Copco and Iron Gate reservoirs were most abundant in mid to late June before quickly disappearing from catches. J. C. Boyle larval suckers peaked in mid July, attained larger sizes, and were caught later in the season. It appeared that recruitment of young-of-the-year suckers only occurred in J. C. Boyle with downstream reservoirs recruiting older individuals, perhaps those that had earlier recruited to J. C. Boyle. Tagging studies could clarify adult recruitment dynamics and an additional study of juvenile recruitment would be needed to confirm these patterns. Predation pressure may be somewhat reduced in J. C. Boyle in comparison to the other reservoirs as its fish community was dominated by native fishes while communities in Copco and Iron Gate reservoirs were dominated by exotic predators. J. C. Boyle also possessed proportionally more littoral habitat, which suggests it may provide a more stable environment for young fishes. However, our sampling was inadequate to demonstrate such relationships due to high variance in larval and juvenile catches and potentially confounding habitat variables. One such variable was water level fluctuations, which could interact with habitat and resource availability in complex ways. For example, water level fluctuations, presumed to have a negative impact, were greatest in J. C. Boyle. Extrapolation from the literature suggests it should have had the poorest habitat for larval and juvenile suckers, but our results indicated J. C. Boyle had the most young suckers. Additional study of the relationships between water level fluctuations, habitat availability, the exotic fish community, and juvenile sucker recruitment would be needed to better understand early life history ecology of endangered lake suckers in these systems. Close

• 11. [Image] Natural history and ecology of larval Lost River suckers and larval shortnose suckers in the Williamson River-Upper Klamath Lake System

  	We monitored larval Lost River and shortnose suckers from natal beds in the Williamson and Sprague rivers to nursery grounds in Upper Klamath Lake. Downstream movements occurred at night, in the middle ...
  	Citation × Citation Citation Abstract Copy Title: Natural history and ecology of larval Lost River suckers and larval shortnose suckers in the Williamson River-Upper Klamath Lake System Author: Cooperman, Michael S. Year: 2004, 2005 We monitored larval Lost River and shortnose suckers from natal beds in the Williamson and Sprague rivers to nursery grounds in Upper Klamath Lake. Downstream movements occurred at night, in the middle of the channel, and on the falling limb of the hydrograph. Ages, sizes, and developmental stages of larvae from spawning beds and the river mouth were similar, while larvae collected contemporaneously from the lake tended to be larger and better fed. Our results indicate in-river rearing was rare, that a rapid outmigration to the lake was favorable for larval survival, and that modification of the lower Williamson River does not appear to have prohibited rapid entry or preclude access to Upper Klamath Lake. Within the Williamson River and Upper Klamath Lake, emergent macrophytes supported significantly higher abundance, larger mean sizes, and better fed larvae than submerged macrophytes, woody vegetation, or open water areas. Analysis of seven years of larval sucker production and survival corroborated the habitat analysis by identifying a positive relationship with emergent macrophyte availability as well as a positive relationship with air temperature and a negative relationship with high wind. These findings illustrate the importance of fast growth, appropriate habitat and calm hydrological conditions for larvae, and are highly consistent with other larval fish studies. Title: Natural history and ecology of larval Lost River suckers and larval shortnose suckers in the Williamson River-Upper Klamath Lake System Author: Cooperman, Michael S. Year: 2004, 2005 We monitored larval Lost River and shortnose suckers from natal beds in the Williamson and Sprague rivers to nursery grounds in Upper Klamath Lake. Downstream movements occurred at night, in the middle of the channel, and on the falling limb of the hydrograph. Ages, sizes, and developmental stages of larvae from spawning beds and the river mouth were similar, while larvae collected contemporaneously from the lake tended to be larger and better fed. Our results indicate in-river rearing was rare, that a rapid outmigration to the lake was favorable for larval survival, and that modification of the lower Williamson River does not appear to have prohibited rapid entry or preclude access to Upper Klamath Lake. Within the Williamson River and Upper Klamath Lake, emergent macrophytes supported significantly higher abundance, larger mean sizes, and better fed larvae than submerged macrophytes, woody vegetation, or open water areas. Analysis of seven years of larval sucker production and survival corroborated the habitat analysis by identifying a positive relationship with emergent macrophyte availability as well as a positive relationship with air temperature and a negative relationship with high wind. These findings illustrate the importance of fast growth, appropriate habitat and calm hydrological conditions for larvae, and are highly consistent with other larval fish studies. Close

• 12. [Image] Geologic and hydrologic characterization and evaluation of the Basin and Range Province relative to the disposal of high-level radioactive waste [part 1 introduction and guidelines]

  	SUMMARY The U.S. Geological Survey's program for geologic and hydrologic evaluation of physiographic provinces to identify areas potentially suitable for locating repository sites for disposal of high-level ...
  	Citation × Citation Citation Abstract Copy Title: Geologic and hydrologic characterization and evaluation of the Basin and Range Province relative to the disposal of high-level radioactive waste [part 1 introduction and guidelines] Author: Bedinger, M. S.; Sargent, Kenneth A.; Reed, J. E. Year: 2008, 2005 SUMMARY The U.S. Geological Survey's program for geologic and hydrologic evaluation of physiographic provinces to identify areas potentially suitable for locating repository sites for disposal of high-level nuclear wastes was announced to the Governors of the eight States in the Basin and Range Province on May 5, 1981. Representatives of Arizona, California, Idaho, New Mexico, Nevada, Oregon, Texas, and Utah, were invited to cooperate with the Federal Government in the evaluation process. Each Governor was requested to nominate an Earth scientist to represent the State in a province working group composed of State and U.S. Geological Survey representatives. This report, Part I of a three-part report, provides the background, introduction and scope of the study. This part also includes a discussion of geologic and hydrologic guidelines that will be used in the evaluation process and illustrates geohydro-logic environments and the effect of individual factors in providing multiple natural barriers to radionuclide migration. Part II is a reconnaissance characterization of the geologic and hydrologic factors to be used in the initial screening of the Basin and Range Province. Part III will be the initial evaluation of the Province and will identify regions that appear suitable for further study. The plan for study of the Province includes a stepwise screening process by which successively smaller land units are considered in increasing detail. Each step involves characterization of the geology and hydrology and selection of subunits for more intensive characterization. Selection of subunits for further study is by evaluation of geologic and hydrologic conditions following a set of guidelines. By representation on the Province Working Group, the States participate in a consultation and review role in: (1) Establishing geologic and hydrologic guidelines, and (2) characterizing and evaluating the Province. The States also participate in compilation of geologic and hydrologic data used in characterizing the Province. The current (1983) needs for a high-level radioactive waste repository include: (1) Disposal in a mined repository; (2) re- trievability of the waste for as much as 50 years; and (3) confidence of isolation of the waste from the accessible environment. Isolation of the waste needs to be assured using geologic and hydrologic conditions that: (1) Minimize risk of inadvertent future intrusions by man; (2) minimize the possibility of disturbance by processes that would expose the waste or increase its mobility; and (3) provide a system of natural barriers to the migration of waste by ground water. The guidelines adopted by the Province Working Group are designed to provide a standard with which these conditions can be compared. The guidelines can be grouped into four principal categories: (1) Potential host media, (2) ground-water conditions, (3) tectonic conditions, and (4) occurrence of natural resources. Ideally the host medium constitutes the first natural barrier to migration of radionculides. The host medium ideally should be a rock type that prevents or retards dissolution and transport of radionuclides. Rocks in both the saturated and unsaturated zones may have desirable characteristics for host media. Rocks?other than the host?in the ground-water flow path from the repository ideally should be major barriers to radionuclide migration. Confining beds of low permeability might be present to retard the rate of flow between more permeable beds. Additionally, sorption of radionuclides by materials such as clays and zeolites in the flow path can further retard the flow of radionuclides by several orders of magnitude. Tectonic conditions in an area should not present a probable cause for exhumation or increased mobility of radioactive waste. Natural resources are a factor for consideration because of the problem of future human intrusion and exposure to radioactivity in the quest for minerals, oil, gas, water, and geothermal resources. The ultimate evaluation of the suitability of a geohydrologic environment for developing a mined repository needs to assess all geologic and hydrologic characteristics and their interaction in providing confidence that a geohydrologic environment will effectively isolate radionuclides from human access. Several hypothetical settings with typical geohydrologic conditions in the Basin and Range Province are used to illustrate the effect of multiple barriers in the isolation of radionuclides. Title: Geologic and hydrologic characterization and evaluation of the Basin and Range Province relative to the disposal of high-level radioactive waste [part 1 introduction and guidelines] Author: Bedinger, M. S.; Sargent, Kenneth A.; Reed, J. E. Year: 2008, 2005 SUMMARY The U.S. Geological Survey's program for geologic and hydrologic evaluation of physiographic provinces to identify areas potentially suitable for locating repository sites for disposal of high-level nuclear wastes was announced to the Governors of the eight States in the Basin and Range Province on May 5, 1981. Representatives of Arizona, California, Idaho, New Mexico, Nevada, Oregon, Texas, and Utah, were invited to cooperate with the Federal Government in the evaluation process. Each Governor was requested to nominate an Earth scientist to represent the State in a province working group composed of State and U.S. Geological Survey representatives. This report, Part I of a three-part report, provides the background, introduction and scope of the study. This part also includes a discussion of geologic and hydrologic guidelines that will be used in the evaluation process and illustrates geohydro-logic environments and the effect of individual factors in providing multiple natural barriers to radionuclide migration. Part II is a reconnaissance characterization of the geologic and hydrologic factors to be used in the initial screening of the Basin and Range Province. Part III will be the initial evaluation of the Province and will identify regions that appear suitable for further study. The plan for study of the Province includes a stepwise screening process by which successively smaller land units are considered in increasing detail. Each step involves characterization of the geology and hydrology and selection of subunits for more intensive characterization. Selection of subunits for further study is by evaluation of geologic and hydrologic conditions following a set of guidelines. By representation on the Province Working Group, the States participate in a consultation and review role in: (1) Establishing geologic and hydrologic guidelines, and (2) characterizing and evaluating the Province. The States also participate in compilation of geologic and hydrologic data used in characterizing the Province. The current (1983) needs for a high-level radioactive waste repository include: (1) Disposal in a mined repository; (2) re- trievability of the waste for as much as 50 years; and (3) confidence of isolation of the waste from the accessible environment. Isolation of the waste needs to be assured using geologic and hydrologic conditions that: (1) Minimize risk of inadvertent future intrusions by man; (2) minimize the possibility of disturbance by processes that would expose the waste or increase its mobility; and (3) provide a system of natural barriers to the migration of waste by ground water. The guidelines adopted by the Province Working Group are designed to provide a standard with which these conditions can be compared. The guidelines can be grouped into four principal categories: (1) Potential host media, (2) ground-water conditions, (3) tectonic conditions, and (4) occurrence of natural resources. Ideally the host medium constitutes the first natural barrier to migration of radionculides. The host medium ideally should be a rock type that prevents or retards dissolution and transport of radionuclides. Rocks in both the saturated and unsaturated zones may have desirable characteristics for host media. Rocks?other than the host?in the ground-water flow path from the repository ideally should be major barriers to radionuclide migration. Confining beds of low permeability might be present to retard the rate of flow between more permeable beds. Additionally, sorption of radionuclides by materials such as clays and zeolites in the flow path can further retard the flow of radionuclides by several orders of magnitude. Tectonic conditions in an area should not present a probable cause for exhumation or increased mobility of radioactive waste. Natural resources are a factor for consideration because of the problem of future human intrusion and exposure to radioactivity in the quest for minerals, oil, gas, water, and geothermal resources. The ultimate evaluation of the suitability of a geohydrologic environment for developing a mined repository needs to assess all geologic and hydrologic characteristics and their interaction in providing confidence that a geohydrologic environment will effectively isolate radionuclides from human access. Several hypothetical settings with typical geohydrologic conditions in the Basin and Range Province are used to illustrate the effect of multiple barriers in the isolation of radionuclides. Close

• 13. [Image] Geologic and hydrologic characterization and evaluation of the Basin and Range Province relative to the disposal of high-level radioactive waste [part 2 geologic and hydrologic characterization ]

  	SUMMARY The geology and hydrology of the Basin and Range Province of the western conterminous United States are characterized in a series of data sets depicted in maps compiled for evaluation of prospective ...
  	Citation × Citation Citation Abstract Copy Title: Geologic and hydrologic characterization and evaluation of the Basin and Range Province relative to the disposal of high-level radioactive waste [part 2 geologic and hydrologic characterization ] Author: Bedinger, M. S.; Sargent, Kenneth A.; Reed, J. E. Year: 2008, 2005 SUMMARY The geology and hydrology of the Basin and Range Province of the western conterminous United States are characterized in a series of data sets depicted in maps compiled for evaluation of prospective areas for further study of geohydrologic environments for isolation of high-level radioactive waste. The data sets include: (1) Average precipitation and evaporation; (2) surface distribution of selected rock types; (3) tectonic conditions; and (4) surface- and ground-water hydrology and Pleistocene lakes and marshes. Rocks mapped for consideration as potential host media for the isolation of high-level radioactive waste are widespread and include argillaceous rocks, granitic rocks, tuffaceous rocks, mafic extrusive rocks, evaporites, and laharic breccias. The unsaturated zone, where probably as thick as 150 meters (500 feet), was mapped for consideration as an environment for isolation of high-level waste. Unsaturated rocks of various lithologic types are widespread in the Province. Tectonic stability in the Quaternary Period is considered the key to assessing the probability of future tectonism with regard to high-level radioactive waste disposal. Tectonic conditions are characterized on the basis of the seismic record, heat-flow measurements, the occurrence of Quaternary faults, vertical crustal movement, and volcanic features. Tectonic activity, as indicated by seismicity, is greatest in areas bordering the western margin of the Province in Nevada and southern California, the eastern margin of the Province bordering the Wasatch Mountains in Utah and in parts of the Rio Grande valley. Late Cenozoic volcanic activity is widespread, being greatest bordering the Sierra Nevada in California and Oregon, and bordering the Wasatch Mountains in southern Utah and Idaho. The arid to semiarid climate of the Province results in few perennial streams and lakes. A large part of the surface drainage is interior and the many closed basins commonly are occupied by playas or dry lake beds. The Province is divided into ground-water flow units defined on the basis of ground-water divides, ground-water flow lines, and surface streams that receive ground-water discharge. Ground water contains less than 500 milligrams per liter of dissolved solids throughout most of the Province. Ground water is more mineralized in areas underlain by evaporitic rocks, overlain by playas, and near saline lakes. Ground water is of the calcium, magnesium, or sodium bicarbonate type in the areas where dissolved-solids concentrations are less than 500 milligrams per liter, and of the calcium, magnesium, or sodium sulfate or chloride type where dissolved-solids concentrations are greater than 500 milligrams per liter. Geologic and hydrologic evidence is found for about 100 lakes and marshes that existed during the Pleistocene Epoch. The possibility of a recurrence of pluvial conditions, such as existed in the Pleistocene, is of concern in repository siting because of possible changes in hydrologic conditions. The Pleistocene lakes and marshes provide clues to the hydrology during pluvial climates. Title: Geologic and hydrologic characterization and evaluation of the Basin and Range Province relative to the disposal of high-level radioactive waste [part 2 geologic and hydrologic characterization ] Author: Bedinger, M. S.; Sargent, Kenneth A.; Reed, J. E. Year: 2008, 2005 SUMMARY The geology and hydrology of the Basin and Range Province of the western conterminous United States are characterized in a series of data sets depicted in maps compiled for evaluation of prospective areas for further study of geohydrologic environments for isolation of high-level radioactive waste. The data sets include: (1) Average precipitation and evaporation; (2) surface distribution of selected rock types; (3) tectonic conditions; and (4) surface- and ground-water hydrology and Pleistocene lakes and marshes. Rocks mapped for consideration as potential host media for the isolation of high-level radioactive waste are widespread and include argillaceous rocks, granitic rocks, tuffaceous rocks, mafic extrusive rocks, evaporites, and laharic breccias. The unsaturated zone, where probably as thick as 150 meters (500 feet), was mapped for consideration as an environment for isolation of high-level waste. Unsaturated rocks of various lithologic types are widespread in the Province. Tectonic stability in the Quaternary Period is considered the key to assessing the probability of future tectonism with regard to high-level radioactive waste disposal. Tectonic conditions are characterized on the basis of the seismic record, heat-flow measurements, the occurrence of Quaternary faults, vertical crustal movement, and volcanic features. Tectonic activity, as indicated by seismicity, is greatest in areas bordering the western margin of the Province in Nevada and southern California, the eastern margin of the Province bordering the Wasatch Mountains in Utah and in parts of the Rio Grande valley. Late Cenozoic volcanic activity is widespread, being greatest bordering the Sierra Nevada in California and Oregon, and bordering the Wasatch Mountains in southern Utah and Idaho. The arid to semiarid climate of the Province results in few perennial streams and lakes. A large part of the surface drainage is interior and the many closed basins commonly are occupied by playas or dry lake beds. The Province is divided into ground-water flow units defined on the basis of ground-water divides, ground-water flow lines, and surface streams that receive ground-water discharge. Ground water contains less than 500 milligrams per liter of dissolved solids throughout most of the Province. Ground water is more mineralized in areas underlain by evaporitic rocks, overlain by playas, and near saline lakes. Ground water is of the calcium, magnesium, or sodium bicarbonate type in the areas where dissolved-solids concentrations are less than 500 milligrams per liter, and of the calcium, magnesium, or sodium sulfate or chloride type where dissolved-solids concentrations are greater than 500 milligrams per liter. Geologic and hydrologic evidence is found for about 100 lakes and marshes that existed during the Pleistocene Epoch. The possibility of a recurrence of pluvial conditions, such as existed in the Pleistocene, is of concern in repository siting because of possible changes in hydrologic conditions. The Pleistocene lakes and marshes provide clues to the hydrology during pluvial climates. Close

• 14. [Image] Geologic and hydrologic characterization and evaluation of the Basin and Range Province relative to the disposal of high-level radioactive waste [part 3 geologic and hydrologic evaluation]

  	SUMMARY This report describes the first phase in evaluating the geology and hydrology of the Basin and Range Province for potential suitability of geohydrologic environments for isolation of high-level ...
  	Citation × Citation Citation Abstract Copy Title: Geologic and hydrologic characterization and evaluation of the Basin and Range Province relative to the disposal of high-level radioactive waste [part 3 geologic and hydrologic evaluation] Author: Bedinger, M. S.; Sargent, Kenneth A.; Reed, J. E. Year: 2008, 2005 SUMMARY This report describes the first phase in evaluating the geology and hydrology of the Basin and Range Province for potential suitability of geohydrologic environments for isolation of high-level radioactive waste. The evaluation of the Province applies the guidelines, discussed in Part I (Bedinger, Sargent, and Reed, 1983) of this report to the geologic and hydrologic information compiled for the Province in Part II (Sargent and Bedinger, 1983). The geologic and hydrologic factors considered in the Province evaluation include distribution of potential host rocks, tectonic conditions and data on ground-water hydrology. Potential host media considered include argillaceous rocks, tuff, basaltic rocks, granitic rocks, evaporites, and the unsaturated zone. The tectonic factors considered are Quaternary faults, late Cenozoic volcanics, seismic activity, heat flow, and late Cenozoic rates of vertical uplift. Hydrologic conditions considered include length of flow path from potential host rocks to discharge areas, interbasin and geothermal flow systems and thick unsaturated sections as potential host media. The Basin and Range Province was divided into 12 subprovinces; each subprovince is evaluated separately and prospective areas for further study are identified. About one-half of the Province appears to have combinations of potential host rocks, tectonic conditions, and ground-water hydrology that merit consideration for further study. The prospective areas for further study in each subprovince are summarized in a brief list of the potentially favorable factors and the issues of concern. Data compiled for the entire Province do not permit a complete evaluation of the f avorability for high-level waste isolation. The evaluations here are intended to identify broad regions that contain potential geohydrologic environments containing multiple natural barriers to radionu-clide migration. Title: Geologic and hydrologic characterization and evaluation of the Basin and Range Province relative to the disposal of high-level radioactive waste [part 3 geologic and hydrologic evaluation] Author: Bedinger, M. S.; Sargent, Kenneth A.; Reed, J. E. Year: 2008, 2005 SUMMARY This report describes the first phase in evaluating the geology and hydrology of the Basin and Range Province for potential suitability of geohydrologic environments for isolation of high-level radioactive waste. The evaluation of the Province applies the guidelines, discussed in Part I (Bedinger, Sargent, and Reed, 1983) of this report to the geologic and hydrologic information compiled for the Province in Part II (Sargent and Bedinger, 1983). The geologic and hydrologic factors considered in the Province evaluation include distribution of potential host rocks, tectonic conditions and data on ground-water hydrology. Potential host media considered include argillaceous rocks, tuff, basaltic rocks, granitic rocks, evaporites, and the unsaturated zone. The tectonic factors considered are Quaternary faults, late Cenozoic volcanics, seismic activity, heat flow, and late Cenozoic rates of vertical uplift. Hydrologic conditions considered include length of flow path from potential host rocks to discharge areas, interbasin and geothermal flow systems and thick unsaturated sections as potential host media. The Basin and Range Province was divided into 12 subprovinces; each subprovince is evaluated separately and prospective areas for further study are identified. About one-half of the Province appears to have combinations of potential host rocks, tectonic conditions, and ground-water hydrology that merit consideration for further study. The prospective areas for further study in each subprovince are summarized in a brief list of the potentially favorable factors and the issues of concern. Data compiled for the entire Province do not permit a complete evaluation of the f avorability for high-level waste isolation. The evaluations here are intended to identify broad regions that contain potential geohydrologic environments containing multiple natural barriers to radionu-clide migration. Close

• 15. [Image] Historical landscape overview of the upper Klamath River Canyon of Oregon and California

  	"Submitted to Klamath Falls Resource Area, Bureau of Land Management, Lakeview District, Klamath Falls, Oregon." ; "Contract no.: HAP032021."; Includes bibliographical references (p. 178-200)
  	Citation × Citation Citation Abstract Copy Title: Historical landscape overview of the upper Klamath River Canyon of Oregon and California Author: Beckham, Stephen Dow Year: 2006, 2008, 2007 "Submitted to Klamath Falls Resource Area, Bureau of Land Management, Lakeview District, Klamath Falls, Oregon." ; "Contract no.: HAP032021."; Includes bibliographical references (p. 178-200) Title: Historical landscape overview of the upper Klamath River Canyon of Oregon and California Author: Beckham, Stephen Dow Year: 2006, 2008, 2007 "Submitted to Klamath Falls Resource Area, Bureau of Land Management, Lakeview District, Klamath Falls, Oregon." ; "Contract no.: HAP032021."; Includes bibliographical references (p. 178-200) Close

• 16. [Image] A geologic and hydrologic reconnaissance of Lava Beds National Monument and vicinity, California

  	A GEOLOGIC AND HYDROLOGIC RECONNAISSANCE OF LAVA BEDS NATIONAL MONUMENT AND VICINITY, CALIFORNIA By William R. Hotchkiss ABSTRACT Lava Beds National Monument is on the Modoc Plateau in Modoc and ...
  	Citation × Citation Citation Abstract Copy Title: A geologic and hydrologic reconnaissance of Lava Beds National Monument and vicinity, California Author: Hotchkiss, W. R Year: 1968, 2008, 2005 A GEOLOGIC AND HYDROLOGIC RECONNAISSANCE OF LAVA BEDS NATIONAL MONUMENT AND VICINITY, CALIFORNIA By William R. Hotchkiss ABSTRACT Lava Beds National Monument is on the Modoc Plateau in Modoc and Siskiyou Counties. The principal geologic units in the vicinity are volcanic rocks,, which in places are highly permeable, and poorly permeable lake sedimentary deposits, all probably post-Oligocene in age. Yields and specific capacities of wells in the unconfined water body within volcanic rocks and lake deposits range widely, but in general are low in the lake deposits and higher in the volcanic rocks. A confined water body, occurring in volcanic rocks underlying the lake deposits yields large quantities of water to three wells in the study area. Dissolved-solids content of ground water generally increases in proportion to the thickness of lake deposits penetrated and to proximity of the lake deposits. Water from wells drilled in the volcanic rocks several miles from the lake deposits, and from wells penetrating the confined water body in volcanic rocks underlying the lake deposits contains small to moderate quantities of dissolved solids. Ground-water supplies can be developed almost anywhere in the study area by drilling wells to depths below the water table. In addition, there is a reasonable possibility of developing wells in a confined water body underlying the water-table system- Title: A geologic and hydrologic reconnaissance of Lava Beds National Monument and vicinity, California Author: Hotchkiss, W. R Year: 1968, 2008, 2005 A GEOLOGIC AND HYDROLOGIC RECONNAISSANCE OF LAVA BEDS NATIONAL MONUMENT AND VICINITY, CALIFORNIA By William R. Hotchkiss ABSTRACT Lava Beds National Monument is on the Modoc Plateau in Modoc and Siskiyou Counties. The principal geologic units in the vicinity are volcanic rocks,, which in places are highly permeable, and poorly permeable lake sedimentary deposits, all probably post-Oligocene in age. Yields and specific capacities of wells in the unconfined water body within volcanic rocks and lake deposits range widely, but in general are low in the lake deposits and higher in the volcanic rocks. A confined water body, occurring in volcanic rocks underlying the lake deposits yields large quantities of water to three wells in the study area. Dissolved-solids content of ground water generally increases in proportion to the thickness of lake deposits penetrated and to proximity of the lake deposits. Water from wells drilled in the volcanic rocks several miles from the lake deposits, and from wells penetrating the confined water body in volcanic rocks underlying the lake deposits contains small to moderate quantities of dissolved solids. Ground-water supplies can be developed almost anywhere in the study area by drilling wells to depths below the water table. In addition, there is a reasonable possibility of developing wells in a confined water body underlying the water-table system- Close

• 17. [Image] Lakeview proposed resource management plan and final environmental impact statement [volume 1]

  	4 v.; maps (some col.); "August 2002"; "January 2003" -- cover
  	Citation × Citation Citation Abstract Copy Title: Lakeview proposed resource management plan and final environmental impact statement [volume 1] Author: U.S. Department of the Interior. Bureau of Land Management; Lakeview Resource Area Office. Lakeview District Year: 2002, 2006, 2005 4 v.; maps (some col.); "August 2002"; "January 2003" -- cover Title: Lakeview proposed resource management plan and final environmental impact statement [volume 1] Author: U.S. Department of the Interior. Bureau of Land Management; Lakeview Resource Area Office. Lakeview District Year: 2002, 2006, 2005 4 v.; maps (some col.); "August 2002"; "January 2003" -- cover Close

• 18. [Image] Macroecology, paleoecology, and ecological integrity of terrestrial species and communities of the interior Columbia River basin and northern portions of the Klamath and Great Basins

  	This report presents information on biogeography and broad-scale ecology (macroecology) of selected fungi, lichens, bryophytes, vascular plants, invertebrates, and vertebrates of the interior Columbia ...
  	Citation × Citation Citation Abstract Copy Title: Macroecology, paleoecology, and ecological integrity of terrestrial species and communities of the interior Columbia River basin and northern portions of the Klamath and Great Basins Author: U.S. Department of Agriculture. Forest Service. Pacific Northwest Research Station; U.S.Department of the Interior. Bureau of Land Management. Year: 1998, 2006, 2005 This report presents information on biogeography and broad-scale ecology (macroecology) of selected fungi, lichens, bryophytes, vascular plants, invertebrates, and vertebrates of the interior Columbia River basin and adjacent areas. Rare plants include many endemics associated with local conditions. Potential plant and invertebrate bioindicators are identified. Species ecological functions differ among communities and variously affect ecosystem diversity and productivity. Species of alpine and subalpine communities are identified that may be at risk from climate change. Maps of terrestrial ecological integrity are presented. Keywords: Macroecology, paleoecology, ecological integrity, terrestrial communities, ecosystems, wildlife, fungi, lichens, bryophytes, vascular plants, invertebrates, arthropods, mollusks, amphibians, reptiles, birds, mammals, endemism, interior Columbia River basin, Klamath Basin, Great Basin. Title: Macroecology, paleoecology, and ecological integrity of terrestrial species and communities of the interior Columbia River basin and northern portions of the Klamath and Great Basins Author: U.S. Department of Agriculture. Forest Service. Pacific Northwest Research Station; U.S.Department of the Interior. Bureau of Land Management. Year: 1998, 2006, 2005 This report presents information on biogeography and broad-scale ecology (macroecology) of selected fungi, lichens, bryophytes, vascular plants, invertebrates, and vertebrates of the interior Columbia River basin and adjacent areas. Rare plants include many endemics associated with local conditions. Potential plant and invertebrate bioindicators are identified. Species ecological functions differ among communities and variously affect ecosystem diversity and productivity. Species of alpine and subalpine communities are identified that may be at risk from climate change. Maps of terrestrial ecological integrity are presented. Keywords: Macroecology, paleoecology, ecological integrity, terrestrial communities, ecosystems, wildlife, fungi, lichens, bryophytes, vascular plants, invertebrates, arthropods, mollusks, amphibians, reptiles, birds, mammals, endemism, interior Columbia River basin, Klamath Basin, Great Basin. Close

• 19. [Image] Genetic analysis of Klamath River green sturgeon (acipensar [i.e. acipenser] medirostris)

  	Abstract The utility of using isozyme analysis to study the stock structure among West Coast populations of green sturgeon (Acipenser medirostris) was assessed. Isozyme analysis was not determined ...
  	Citation × Citation Citation Abstract Copy Title: Genetic analysis of Klamath River green sturgeon (acipensar [i.e. acipenser] medirostris) Author: Mulligan, Helen Year: 2000, 2005 Abstract The utility of using isozyme analysis to study the stock structure among West Coast populations of green sturgeon (Acipenser medirostris) was assessed. Isozyme analysis was not determined to be an adequate method for assessing stock structure in green sturgeon for the following reasons: 1) the complex nature of isozyme expression 2) the relatively poor resolution of enzyme systems for our samples 3) the invasive nature of collecting tissue samples for isozyme analysis, which necessitates sacrificing the fish, precludes collection of samples from some rivers. The stomach contents of 23 green sturgeon collected from fish harvested in the Klamath River were analyzed. Only four stomachs contained identifiable food items, with the others containing food far too digested for identification, gravel, or no contents. Two stomachs contained the small gastropod, Olivellapyna, one stomach contained the carapace remains of a female Dungeness crab, Cancer magister, and one stomach contained the posterior portions of three ammocoetes, Lampetra tridentata. Preliminary analysis was conducted using mtDNA to assess the potential of using this technique for assessing the stock structure of green sturgeon. Although the Klamath River Fishery Restoration Program did not fund this analysis, the results are presented because this work was designed to yield complementary information to the isozyme study. No diagnostic differences were detected between samples collected from the Klamath River and the Columbia River estuary using Restriction Fragment Length Polymorphism analysis. Study results indicated that microsateliite DNA analyst might be the most appropriate current genetic technique for assessing the population structure of green sturgeon. Title: Genetic analysis of Klamath River green sturgeon (acipensar [i.e. acipenser] medirostris) Author: Mulligan, Helen Year: 2000, 2005 Abstract The utility of using isozyme analysis to study the stock structure among West Coast populations of green sturgeon (Acipenser medirostris) was assessed. Isozyme analysis was not determined to be an adequate method for assessing stock structure in green sturgeon for the following reasons: 1) the complex nature of isozyme expression 2) the relatively poor resolution of enzyme systems for our samples 3) the invasive nature of collecting tissue samples for isozyme analysis, which necessitates sacrificing the fish, precludes collection of samples from some rivers. The stomach contents of 23 green sturgeon collected from fish harvested in the Klamath River were analyzed. Only four stomachs contained identifiable food items, with the others containing food far too digested for identification, gravel, or no contents. Two stomachs contained the small gastropod, Olivellapyna, one stomach contained the carapace remains of a female Dungeness crab, Cancer magister, and one stomach contained the posterior portions of three ammocoetes, Lampetra tridentata. Preliminary analysis was conducted using mtDNA to assess the potential of using this technique for assessing the stock structure of green sturgeon. Although the Klamath River Fishery Restoration Program did not fund this analysis, the results are presented because this work was designed to yield complementary information to the isozyme study. No diagnostic differences were detected between samples collected from the Klamath River and the Columbia River estuary using Restriction Fragment Length Polymorphism analysis. Study results indicated that microsateliite DNA analyst might be the most appropriate current genetic technique for assessing the population structure of green sturgeon. Close

• 20. [Image] Implementation of the Endangered Species Act of 1973 (Report to the House Committee on Resources)

  	I. Executive Summary There is increasing recognition from most quarters that the Endangered Species Act (ESA) needs to be improved. Exactly what those improvements should be is less uniform. ...
  	Citation × Citation Citation Abstract Copy Title: Implementation of the Endangered Species Act of 1973 (Report to the House Committee on Resources) Author: United States. Congress. House. Committee on Resources Year: 2005, 2007 I. Executive Summary There is increasing recognition from most quarters that the Endangered Species Act (ESA) needs to be improved. Exactly what those improvements should be is less uniform. This report examines the implementation of selected aspects of the endangered species program relying predominately on information provided by the primary implementing agencies, the United States Fish and Wildlife Service (FWS) and National Marine Fisheries Service (NMFS) and offers some recommendations for possible improvements to the program. Debate over the ESA has traditionally been highly polarized. For example, compensating landowners for takings or reductions in property value has been opposed by some who argue updating the law to address this is not necessary. While consensus on other issues such as the need for increasing conservation incentives and the role states play in endangered species conservation has begun to emerge, one of the most debated aspects of ESA implementation continues to be whether the ESA is effectively conserving endangered and threatened species. While there have been significant strides in conserving individual species such as the whooping crane, red-cockaded woodpecker and gray wolf, few species have been delisted (removed from the endangered list) or downlisted (changed in status from endangered to threatened) because of successful ESA conservation efforts. Some argue that the number of recovered species is an unfair measure, asserting that the three decades the ESA has been in existence is an insufficient amount of time for the lengthy process of species recovery and point to listed species that have not gone extinct as evidence the ESA 'saves' species. From the opposing perspective, while recovery to the point of delisting may require a substantial amount of time for many species, after three decades more progress should be demonstrable through species that have recovered and been delisted. Even if a species has increased in numbers or distribution or the threats facing the species have been reduced, if it has not been delisted on the basis of recovery, the ESA's prohibitions and regulations remain applicable and the ESA should not be a 'one way street.' Of 40 total species removed from the list, 10 domestic species were delisted because of "recovery". Of 33 reclassified species, 10 domestic downlistings (a change from endangered to threatened status) reflected a reduced threat assessment which also allowed more flexibility in management. The FWS's most recent report to Congress (Fiscal years 2001-2002) shows that 77 percent of listed species fall in the 0 to 25 percent recovery achieved bracket and 2 percent fall in the 76 to 100 percent recovery achieved bracket. 39 percent of the FWS managed species are of uncertain status. Of those with an assessed trend, at one end of the spectrum are 3 percent possibly extinct, 1 percent occurring only in captivity and 21 percent declining and at the other end are 30 percent stable and 6 percent improving. These assessments however are subjective. Additionally, the assessment that a species is improving or stable may reflect, for example, a reduction in perceived threats or corrections to inaccurate threat assessments that stemmed from erroneous data rather than actual changes in species' trends that are demonstrated by improved numbers, distribution or other such measurements. Consequently, a meaningful assessment of conservation trends under the ESA using these data is not possible. The data used to list a number of species has been subsequently determined to be erroneous and species that likely do not merit classification as endangered or threatened remain listed. This can consume resources that could be directed to species that do merit listing. The assignment of recovery priorities appears highly skewed and the recovery priority for some species seems questionable. A meaningful distinction between endangered status and threatened status has been blurred as has been the framework for the mechanism of critical habitat. Expenditure reporting has improved but presents an incomplete picture of financial resources dedicated to endangered species. Workloads for litigation regarding activities such as consultation and listing under the ESA's complex structure compete for resources that could otherwise be directed at recovery efforts. The demands associated with ESA Section 4 determinations in combination with the pace of species listings and delistings, the number of possible future additions to the list and the economic impact of listings likely indicate that the current program is not sustainable. Title: Implementation of the Endangered Species Act of 1973 (Report to the House Committee on Resources) Author: United States. Congress. House. Committee on Resources Year: 2005, 2007 I. Executive Summary There is increasing recognition from most quarters that the Endangered Species Act (ESA) needs to be improved. Exactly what those improvements should be is less uniform. This report examines the implementation of selected aspects of the endangered species program relying predominately on information provided by the primary implementing agencies, the United States Fish and Wildlife Service (FWS) and National Marine Fisheries Service (NMFS) and offers some recommendations for possible improvements to the program. Debate over the ESA has traditionally been highly polarized. For example, compensating landowners for takings or reductions in property value has been opposed by some who argue updating the law to address this is not necessary. While consensus on other issues such as the need for increasing conservation incentives and the role states play in endangered species conservation has begun to emerge, one of the most debated aspects of ESA implementation continues to be whether the ESA is effectively conserving endangered and threatened species. While there have been significant strides in conserving individual species such as the whooping crane, red-cockaded woodpecker and gray wolf, few species have been delisted (removed from the endangered list) or downlisted (changed in status from endangered to threatened) because of successful ESA conservation efforts. Some argue that the number of recovered species is an unfair measure, asserting that the three decades the ESA has been in existence is an insufficient amount of time for the lengthy process of species recovery and point to listed species that have not gone extinct as evidence the ESA 'saves' species. From the opposing perspective, while recovery to the point of delisting may require a substantial amount of time for many species, after three decades more progress should be demonstrable through species that have recovered and been delisted. Even if a species has increased in numbers or distribution or the threats facing the species have been reduced, if it has not been delisted on the basis of recovery, the ESA's prohibitions and regulations remain applicable and the ESA should not be a 'one way street.' Of 40 total species removed from the list, 10 domestic species were delisted because of "recovery". Of 33 reclassified species, 10 domestic downlistings (a change from endangered to threatened status) reflected a reduced threat assessment which also allowed more flexibility in management. The FWS's most recent report to Congress (Fiscal years 2001-2002) shows that 77 percent of listed species fall in the 0 to 25 percent recovery achieved bracket and 2 percent fall in the 76 to 100 percent recovery achieved bracket. 39 percent of the FWS managed species are of uncertain status. Of those with an assessed trend, at one end of the spectrum are 3 percent possibly extinct, 1 percent occurring only in captivity and 21 percent declining and at the other end are 30 percent stable and 6 percent improving. These assessments however are subjective. Additionally, the assessment that a species is improving or stable may reflect, for example, a reduction in perceived threats or corrections to inaccurate threat assessments that stemmed from erroneous data rather than actual changes in species' trends that are demonstrated by improved numbers, distribution or other such measurements. Consequently, a meaningful assessment of conservation trends under the ESA using these data is not possible. The data used to list a number of species has been subsequently determined to be erroneous and species that likely do not merit classification as endangered or threatened remain listed. This can consume resources that could be directed to species that do merit listing. The assignment of recovery priorities appears highly skewed and the recovery priority for some species seems questionable. A meaningful distinction between endangered status and threatened status has been blurred as has been the framework for the mechanism of critical habitat. Expenditure reporting has improved but presents an incomplete picture of financial resources dedicated to endangered species. Workloads for litigation regarding activities such as consultation and listing under the ESA's complex structure compete for resources that could otherwise be directed at recovery efforts. The demands associated with ESA Section 4 determinations in combination with the pace of species listings and delistings, the number of possible future additions to the list and the economic impact of listings likely indicate that the current program is not sustainable. Close

• 21. [Image] Report of 1994 Workshop on the Correlation of Marine and Terrestrial Records of Climate Changes in the Western United States

  	Imprint from transmittal sheet; Distributed to depository libraries in microfiche; Shipping list no.: 97-0071-M; One ill. on 1 folded leaf in pocket; Includes bibliographical references
  	Citation × Citation Citation Abstract Copy Title: Report of 1994 Workshop on the Correlation of Marine and Terrestrial Records of Climate Changes in the Western United States Author: Workshop on the Correlation of Marine and Terrestrial Records of Climate Changes in the Western U.S. (3rd : 1994 : Watsonville, Calif.) Year: 1996, 2007, 2005 Imprint from transmittal sheet; Distributed to depository libraries in microfiche; Shipping list no.: 97-0071-M; One ill. on 1 folded leaf in pocket; Includes bibliographical references Title: Report of 1994 Workshop on the Correlation of Marine and Terrestrial Records of Climate Changes in the Western United States Author: Workshop on the Correlation of Marine and Terrestrial Records of Climate Changes in the Western U.S. (3rd : 1994 : Watsonville, Calif.) Year: 1996, 2007, 2005 Imprint from transmittal sheet; Distributed to depository libraries in microfiche; Shipping list no.: 97-0071-M; One ill. on 1 folded leaf in pocket; Includes bibliographical references Close

• 22. [Image] IMST review of the USFWS and NMFS 2001 biological opinions on management of the Klamath Reclamation Project and related reports: a report of the Independent Multidisciplinary Science Team, Oregon Plan for Salmon and Watersheds

  	This report is a review of scientific research done by various organizations involved in the Klamath Reclamation Project to assess the "status and management of coho salmon in the Klamath River and . . ...
  	Citation × Citation Citation Abstract Copy Title: IMST review of the USFWS and NMFS 2001 biological opinions on management of the Klamath Reclamation Project and related reports: a report of the Independent Multidisciplinary Science Team, Oregon Plan for Salmon and Watersheds Author: Independent Multidisciplinary Science Team (Oregon) Year: 2003, 2004 This report is a review of scientific research done by various organizations involved in the Klamath Reclamation Project to assess the "status and management of coho salmon in the Klamath River and . . . management of Upper Klamath Lake and its watershed"; "April 16, 2003"; Includes bibliographical references (p. 104-112) Title: IMST review of the USFWS and NMFS 2001 biological opinions on management of the Klamath Reclamation Project and related reports: a report of the Independent Multidisciplinary Science Team, Oregon Plan for Salmon and Watersheds Author: Independent Multidisciplinary Science Team (Oregon) Year: 2003, 2004 This report is a review of scientific research done by various organizations involved in the Klamath Reclamation Project to assess the "status and management of coho salmon in the Klamath River and . . . management of Upper Klamath Lake and its watershed"; "April 16, 2003"; Includes bibliographical references (p. 104-112) Close

• 23. [Image] Recovery plan for the native fishes of the Warner Basin and Alkali Subbasin : Warner sucker (threatened) Catostomus warnerensis, Hutton tui chub (threatened) Gila bicolor ssp. Foskett speckled dace (threatened) Rhinichthys osculus ssp

  	"April 1998"--P. [4] of cover; Includes bibliographical references (p. 57-66)
  	Citation × Citation Citation Abstract Copy Title: Recovery plan for the native fishes of the Warner Basin and Alkali Subbasin : Warner sucker (threatened) Catostomus warnerensis, Hutton tui chub (threatened) Gila bicolor ssp. Foskett speckled dace (threatened) Rhinichthys osculus ssp Author: U.S. Fish and Wildlife Service. Oregon State Office Year: 1998, 2004 "April 1998"--P. [4] of cover; Includes bibliographical references (p. 57-66) Title: Recovery plan for the native fishes of the Warner Basin and Alkali Subbasin : Warner sucker (threatened) Catostomus warnerensis, Hutton tui chub (threatened) Gila bicolor ssp. Foskett speckled dace (threatened) Rhinichthys osculus ssp Author: U.S. Fish and Wildlife Service. Oregon State Office Year: 1998, 2004 "April 1998"--P. [4] of cover; Includes bibliographical references (p. 57-66) Close

• 24. [Image] Groundwater investigation of Bonanza Springs, Yonna, Poe and Langel valleys

  	PURPOSE, SCOPE AND METHODOLOGY A reconnaissance study was designed to collect, compile, and analyze data to determine if ground-water use would interfere with surface water sources near Big Bonanza Springs. ...
  	Citation × Citation Citation Abstract Copy Title: Groundwater investigation of Bonanza Springs, Yonna, Poe and Langel valleys Author: Gorman, Kyle G. Year: 1994, 2004 PURPOSE, SCOPE AND METHODOLOGY A reconnaissance study was designed to collect, compile, and analyze data to determine if ground-water use would interfere with surface water sources near Big Bonanza Springs. The study was to last one year from July 1992 to June 1993. Periodic water level measurements and stream flow measurements have been made since June 1993, to create a more complete data set. Water level measurements in selected wells were made periodically to determine groundwater level fluctuations over time. A continuous water level recorder was installed in one well in September 1992 and is currently scheduled to run until spring 1994, when its status will be evaluated. The emphasis on work in the local area around Bonanza included monthly water level measurements, Lost River stream flow measurements, and Bonanza Springs weir measurements. This area has the highest concentration of wells, both domestic and irrigation, and is of particular interest because of the large aggregate discharge of groundwater in a short reach of the Lost River. To quantify the discharge of the Bonanza Springs, wading stream flow measurements were made above and below the section of the Lost River where groundwater is known to discharge. The difference between the two measurements was assumed to give the discharge of the springs in that reach. To correlate the overall flow of Bonanza Springs to the direct measurement of some of the discharge points, various-sized rectangular weirs were placed in the northern channel of the springs in the Big Bonanza Springs Park. The comparison could then be made by making sets of measurements at all locations in a single day. The total potential use was determined by summing the number of cubic feet per second (cfs) on the pending applications filed with OWRD for the appropriation of groundwater in the area within the study boundaries. This area coincides with the valley lowland areas. The total maximum rate of appropriation under terms of existing permits was determined by valley only in Langell Valley for the 1992 irrigation season. This was done by summing the individual rates in permits for irrigation, stock and domestic purposes, if any. This total included all issued permits and emergency drought permits exclusively from groundwater. Sample drill cuttings were collected from wells under construction during the study period within the study boundaries. The samples were examined in an effort to correlate geology defined in past studies with present knowledge. They were also used to conceptualize the subsurface geology. A video log of the well bore in which the continuous water level recorder was installed was done in early October 1992. Since this well was constructed prior to the requirement of a well drilling report, a video log of the rock types throughout the well bore was recorded. This information was important in evaluating static water level information also collected by the recorder. Title: Groundwater investigation of Bonanza Springs, Yonna, Poe and Langel valleys Author: Gorman, Kyle G. Year: 1994, 2004 PURPOSE, SCOPE AND METHODOLOGY A reconnaissance study was designed to collect, compile, and analyze data to determine if ground-water use would interfere with surface water sources near Big Bonanza Springs. The study was to last one year from July 1992 to June 1993. Periodic water level measurements and stream flow measurements have been made since June 1993, to create a more complete data set. Water level measurements in selected wells were made periodically to determine groundwater level fluctuations over time. A continuous water level recorder was installed in one well in September 1992 and is currently scheduled to run until spring 1994, when its status will be evaluated. The emphasis on work in the local area around Bonanza included monthly water level measurements, Lost River stream flow measurements, and Bonanza Springs weir measurements. This area has the highest concentration of wells, both domestic and irrigation, and is of particular interest because of the large aggregate discharge of groundwater in a short reach of the Lost River. To quantify the discharge of the Bonanza Springs, wading stream flow measurements were made above and below the section of the Lost River where groundwater is known to discharge. The difference between the two measurements was assumed to give the discharge of the springs in that reach. To correlate the overall flow of Bonanza Springs to the direct measurement of some of the discharge points, various-sized rectangular weirs were placed in the northern channel of the springs in the Big Bonanza Springs Park. The comparison could then be made by making sets of measurements at all locations in a single day. The total potential use was determined by summing the number of cubic feet per second (cfs) on the pending applications filed with OWRD for the appropriation of groundwater in the area within the study boundaries. This area coincides with the valley lowland areas. The total maximum rate of appropriation under terms of existing permits was determined by valley only in Langell Valley for the 1992 irrigation season. This was done by summing the individual rates in permits for irrigation, stock and domestic purposes, if any. This total included all issued permits and emergency drought permits exclusively from groundwater. Sample drill cuttings were collected from wells under construction during the study period within the study boundaries. The samples were examined in an effort to correlate geology defined in past studies with present knowledge. They were also used to conceptualize the subsurface geology. A video log of the well bore in which the continuous water level recorder was installed was done in early October 1992. Since this well was constructed prior to the requirement of a well drilling report, a video log of the rock types throughout the well bore was recorded. This information was important in evaluating static water level information also collected by the recorder. Close

• 25. [Image] Nitrogen and phosphorus loading from drained wetlands adjacent to Upper Klamath and Agency Lakes, Oregon

  	Two maps digitized separately; Includes bibliographical references (p. 44-49)
  	Citation × Citation Citation Abstract Copy Title: Nitrogen and phosphorus loading from drained wetlands adjacent to Upper Klamath and Agency Lakes, Oregon Author: Snyder, Daniel T. Year: 1997, 2005, 2004 Two maps digitized separately; Includes bibliographical references (p. 44-49) Title: Nitrogen and phosphorus loading from drained wetlands adjacent to Upper Klamath and Agency Lakes, Oregon Author: Snyder, Daniel T. Year: 1997, 2005, 2004 Two maps digitized separately; Includes bibliographical references (p. 44-49) Close

• 26. [Image] An assessment of ecosystem components in the interior Columbia Basin and portions of the Klamath and Great Basins [volume 1]

  	Quigley, Thomas M.; Arbelbide, Sylvia J., tech. eds. 1997. An assessment of ecosystem components in the interior Columbia basin and portions of the Klamath and Great Basins: volume 1. Gen. Tech. Rep. PNW-GTR-405. ...
  	Citation × Citation Citation Abstract Copy Title: An assessment of ecosystem components in the interior Columbia Basin and portions of the Klamath and Great Basins [volume 1] Author: Quigley, Thomas Milton; Arbelbide, S. J. (Sylvia J.) Year: 1997, 2008, 2005 Quigley, Thomas M.; Arbelbide, Sylvia J., tech. eds. 1997. An assessment of ecosystem components in the interior Columbia basin and portions of the Klamath and Great Basins: volume 1. Gen. Tech. Rep. PNW-GTR-405. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 4 vol. (Quigley, Thomas M., tech. ed.; The Interior Columbia Basin Ecosystem Management Project: Scientific Assessment). The Assessment of Ecosystem Components in the Interior Columbia Basin and Portions of the Klamath and Great Basins provides detailed information about current conditions and trends for the biophysical and social systems within the Basin. This information can be used by land managers to develop broad land management goals and priorities and provides the context for decisions specific to smaller geographic areas. The Assessment area covers about 8 percent of the U.S. land area, 24 percent of the Nation's National Forest System lands, 10 percent of the Nation's BLM-administered lands, and contains about 1.2 percent of the Nation's population. This results in a population density that is less than one-sixth of the U.S. average. The area has experienced recent, rapid population growth and generally has a robust, diverse economy. As compared to historic conditions, the terrestrial, aquatic, forest, and rangeland systems have undergone dramatic changes. Forested landscapes are more susceptible to fire, insect, and disease than under historic conditions. Rangelands are highly susceptible to noxious weed invasion. The disturbance regimes that operate on forest and rangeland have changed substantially, with lethal fires dominating many areas where non-lethal fires were the norm historically. Terrestrial habitats that have experienced the greatest decline include the native grassland, native shrubland, and old forest structures. There are areas within the Assessment area that have higher diversity than others. Aquatic systems are now more fragmented and isolated than historically and the introduction of non-native fish species has complicated current status of native fishes. Core habitat and population centers do remain as building blocks for restoration. Social and economic conditions within the Assessment area vary considerably, depending to a great extent on population, diversity of employment opportunities, and changing demographics. Those counties with the higher population densities and greater diversity of employment opportunities are generally more resilient to economic downturns. This Assessment provides a rich information base, including over 170 mapped themes with associated models and databases, from which future decisions can benefit. Keywords: Columbia basin, biophysical systems, social systems, ecosystem. Title: An assessment of ecosystem components in the interior Columbia Basin and portions of the Klamath and Great Basins [volume 1] Author: Quigley, Thomas Milton; Arbelbide, S. J. (Sylvia J.) Year: 1997, 2008, 2005 Quigley, Thomas M.; Arbelbide, Sylvia J., tech. eds. 1997. An assessment of ecosystem components in the interior Columbia basin and portions of the Klamath and Great Basins: volume 1. Gen. Tech. Rep. PNW-GTR-405. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 4 vol. (Quigley, Thomas M., tech. ed.; The Interior Columbia Basin Ecosystem Management Project: Scientific Assessment). The Assessment of Ecosystem Components in the Interior Columbia Basin and Portions of the Klamath and Great Basins provides detailed information about current conditions and trends for the biophysical and social systems within the Basin. This information can be used by land managers to develop broad land management goals and priorities and provides the context for decisions specific to smaller geographic areas. The Assessment area covers about 8 percent of the U.S. land area, 24 percent of the Nation's National Forest System lands, 10 percent of the Nation's BLM-administered lands, and contains about 1.2 percent of the Nation's population. This results in a population density that is less than one-sixth of the U.S. average. The area has experienced recent, rapid population growth and generally has a robust, diverse economy. As compared to historic conditions, the terrestrial, aquatic, forest, and rangeland systems have undergone dramatic changes. Forested landscapes are more susceptible to fire, insect, and disease than under historic conditions. Rangelands are highly susceptible to noxious weed invasion. The disturbance regimes that operate on forest and rangeland have changed substantially, with lethal fires dominating many areas where non-lethal fires were the norm historically. Terrestrial habitats that have experienced the greatest decline include the native grassland, native shrubland, and old forest structures. There are areas within the Assessment area that have higher diversity than others. Aquatic systems are now more fragmented and isolated than historically and the introduction of non-native fish species has complicated current status of native fishes. Core habitat and population centers do remain as building blocks for restoration. Social and economic conditions within the Assessment area vary considerably, depending to a great extent on population, diversity of employment opportunities, and changing demographics. Those counties with the higher population densities and greater diversity of employment opportunities are generally more resilient to economic downturns. This Assessment provides a rich information base, including over 170 mapped themes with associated models and databases, from which future decisions can benefit. Keywords: Columbia basin, biophysical systems, social systems, ecosystem. Close

• 27. [Image] Soils of the Klamath Indian Reservation; interim report, June 11, 1958

  	TABLE OF CONTENTS PART I INTRODUCTION 18 - 11 History and ethnology 18 Irrigated area table 19 Cultural geography 19 General physiographic features 262e . .3 Physiographic areas and farming 1d CLIMATE ...
  	Citation × Citation Citation Abstract Copy Title: Soils of the Klamath Indian Reservation; interim report, June 11, 1958 Author: United States. Bureau of Indian Affairs Year: 1958, 2005, 2004 TABLE OF CONTENTS PART I INTRODUCTION 18 - 11 History and ethnology 18 Irrigated area table 19 Cultural geography 19 General physiographic features 262e . .3 Physiographic areas and farming 1d CLIMATE 182 - 18 Climatic table, Sprague River, Oregon 185 Precipitation table , Chiloquin, Oregon 186 Temperature table, Chiloquin, Oregon 187 Climatic table, Fort Klamath, Oregon 188 VEGETATION 189 - 25 GEOLOGY 196 - 51 Hydrography: rivers, lakes, marshes, ground water 196 Relief and geological formations. 262e .32 Diatomite - tuff formation 262e . 1c4 Pliocene sediments of the Modoc Point area 262e.. 37 Faulted tuff formation 1c9 Pumice tuff formation.. 1d0 Pumice mantle and pumice flows ........ 262e.... .........40 Table of chemical analyses of pumice and scoria 1d5 Geology Map 262e . 262e 221 BIBLIOGRAPHY 262e 262e...52 PART II DESCRIPTIONS OF SOILS 223 - 60 Classification and survey 262e 262e.. 262e... 53 Soil profile and nomenclature. .... 262e...53 Chestnut Soils 262e 224 "Western" Brown Forest Soils 225 Regosol Soils . . 262e. 262e......56 Solonetz Soils 262e.....57 Halomorphic Soils 262e 228 Hydromorphic Soils 262e... 229 Soil Association Map 262e 229 KEY TO SOIL SERIES 262e61 - 63 SOIL SERIES AND MAPPING UNIT DESCRIPTIONS 134 ~ 254 APPENDIX 1955 - 297 Soil Series and mapping unit index. 2620. . . . 255 Glossary of terms 263f 262e. . . . 272 Table of soil analyses (Oregon State College)... 1989 Table of irrigation water quality (Oregon State College) 1990 Table of conductivity and reaction. . . . 1991 Table of resistance of saturated paste 262e296 Title: Soils of the Klamath Indian Reservation; interim report, June 11, 1958 Author: United States. Bureau of Indian Affairs Year: 1958, 2005, 2004 TABLE OF CONTENTS PART I INTRODUCTION 18 - 11 History and ethnology 18 Irrigated area table 19 Cultural geography 19 General physiographic features 262e . .3 Physiographic areas and farming 1d CLIMATE 182 - 18 Climatic table, Sprague River, Oregon 185 Precipitation table , Chiloquin, Oregon 186 Temperature table, Chiloquin, Oregon 187 Climatic table, Fort Klamath, Oregon 188 VEGETATION 189 - 25 GEOLOGY 196 - 51 Hydrography: rivers, lakes, marshes, ground water 196 Relief and geological formations. 262e .32 Diatomite - tuff formation 262e . 1c4 Pliocene sediments of the Modoc Point area 262e.. 37 Faulted tuff formation 1c9 Pumice tuff formation.. 1d0 Pumice mantle and pumice flows ........ 262e.... .........40 Table of chemical analyses of pumice and scoria 1d5 Geology Map 262e . 262e 221 BIBLIOGRAPHY 262e 262e...52 PART II DESCRIPTIONS OF SOILS 223 - 60 Classification and survey 262e 262e.. 262e... 53 Soil profile and nomenclature. .... 262e...53 Chestnut Soils 262e 224 "Western" Brown Forest Soils 225 Regosol Soils . . 262e. 262e......56 Solonetz Soils 262e.....57 Halomorphic Soils 262e 228 Hydromorphic Soils 262e... 229 Soil Association Map 262e 229 KEY TO SOIL SERIES 262e61 - 63 SOIL SERIES AND MAPPING UNIT DESCRIPTIONS 134 ~ 254 APPENDIX 1955 - 297 Soil Series and mapping unit index. 2620. . . . 255 Glossary of terms 263f 262e. . . . 272 Table of soil analyses (Oregon State College)... 1989 Table of irrigation water quality (Oregon State College) 1990 Table of conductivity and reaction. . . . 1991 Table of resistance of saturated paste 262e296 Close

• 28. [Image] Oregon Plan for Salmon and Watersheds biennial report, 2005-2007

  	The Oregon Plan for Salmon and Watersheds Biennial Report 2005-2007. This is the sixth report on the Oregon Plan for Salmon and Watersheds. The report provides an update on the accomplishments and continuing ...
  	Citation × Citation Citation Abstract Copy Title: Oregon Plan for Salmon and Watersheds biennial report, 2005-2007 Author: Oregon Watershed Enhancement Board Year: 2006, 2007 The Oregon Plan for Salmon and Watersheds Biennial Report 2005-2007. This is the sixth report on the Oregon Plan for Salmon and Watersheds. The report provides an update on the accomplishments and continuing efforts of people throughout Oregon to improve and protect clean water and recover and maintain healthy populations offish and wildlife in our watersheds. The Oregon Plan is unique because it engages communities in the restoration and long-term stewardship of their watersheds. This extraordinary effort encourages local partnerships and voluntary actions to improve the conditions of our watersheds. Over the years, these actions have made Oregon a national leader in local cooperative conservation. This report collects project and condition data, voluntary private lands restoration information, and agency program accomplishments under the Oregon Plan. Consistent with the past two reports, this document continues to provide specific data on each of the state's fifteen reporting basins. A new element to this report is the inclusion of stories about the people, partnerships, and on-the-ground projects that are benefiting watersheds and communities across the state. Thanks to the many Oregon Plan partners who contributed to this report. Thomas M. Byler Executive Director Oregon Watershed Enhancement Board Title: Oregon Plan for Salmon and Watersheds biennial report, 2005-2007 Author: Oregon Watershed Enhancement Board Year: 2006, 2007 The Oregon Plan for Salmon and Watersheds Biennial Report 2005-2007. This is the sixth report on the Oregon Plan for Salmon and Watersheds. The report provides an update on the accomplishments and continuing efforts of people throughout Oregon to improve and protect clean water and recover and maintain healthy populations offish and wildlife in our watersheds. The Oregon Plan is unique because it engages communities in the restoration and long-term stewardship of their watersheds. This extraordinary effort encourages local partnerships and voluntary actions to improve the conditions of our watersheds. Over the years, these actions have made Oregon a national leader in local cooperative conservation. This report collects project and condition data, voluntary private lands restoration information, and agency program accomplishments under the Oregon Plan. Consistent with the past two reports, this document continues to provide specific data on each of the state's fifteen reporting basins. A new element to this report is the inclusion of stories about the people, partnerships, and on-the-ground projects that are benefiting watersheds and communities across the state. Thanks to the many Oregon Plan partners who contributed to this report. Thomas M. Byler Executive Director Oregon Watershed Enhancement Board Close

• 29. [Image] Geology and ground-water resources of the Swan Lake-Yonna Valleys area, Klamath County, Oregon

  	Abstract The Swan Lake-Yonna Valleys area consists of two intermountain valleys with their subordinate side valleys adjoining slopes, and mountainous boundary ridges, In all the area covered is about 256 ...
  	Citation × Citation Citation Abstract Copy Title: Geology and ground-water resources of the Swan Lake-Yonna Valleys area, Klamath County, Oregon Author: Meyers, Joseph D. Year: 1952, 2007, 2005 Abstract The Swan Lake-Yonna Valleys area consists of two intermountain valleys with their subordinate side valleys adjoining slopes, and mountainous boundary ridges, In all the area covered is about 256 square miles but the essential agricultural sections are restricted to the floors of Swan Lake and Yonna valleys with their respective subsidiary extensions of Pine Flats and Alkali Lake flats, a valley-floor area totaling about 90 square miles The floors of Swan Lake Valley and Yonna Valley lie at an altitude of about U52OO feet but the mountainous boundary ridges rise generally to 6000 feeto Yonna Valley is largely drained to Lost River by Buck Creek but also in part to Alkali Lakeo Swan Lake Valley and Pine Flats have only internal drainage. The Swan Lake Valley floor is the top of a deep alluvial fill, while Yonna Valley floor is mainly an erosional surface sloping to lines of through drainage Precipitation is about lit inches annually on the valley floors 9 but must be much more, possibly 18 to 24 inches, on the higher parts of the drainage basins. The growing season is short and killing frosts do occur in late spring and early fall. The rock units forming the bedrock structure of the area are consolidated or semiconsolidated rocks of Tertiary age and are largely of volcanic-flow and volcanic-sedimentary originc They consist of three main elements, a lower lava-rock unit, a sedimentary and volcanic-sedimentary unit, and an upper lava-rock unito The unconsolidated deposits are the older alluvium of Quaternary (and in part of late-Tertiary) age and the younger alluvium of Quaternary age0 The bedrock is faulted and deformed particularly so along a northwest-southeast set of fault lines that have given a remarkable linearity to the topography. Unpublished records subject to revision Ground water occurs below a regional water table that slopes south-ward to the level of the Lost Rivero The upper lava rocks and the lower lava rocks contain the principal permeable zones that occur beneath the areao Breccia and other porous zones in those rocks in places yield water to wells at a rate as large as 35OOO gallons per minute with but 1 or 2 feet of drawdowno The economical construction of irrigation wells requires the determination of the best possible location at which those rocks may be tapped at shallow depth below the level of the water tableo The ground water in general relatively low in dissolved mineral matter and is but slightly to moderately hard and would be considered chemically satisfactory for most uaeso Irrigation is the principal use of the ground water in the area north of the Horsefly Irrigation Districto There 3? wells supplied about 6,000 acre-feet of water to about 3800 acres of land in 1950. Water-level records obtained since 19U8 and approximations of the probable annual recharge from precipitation indicate that the present withdrawals are considerably less than the annual increment of the ground-water recharge, Rough estimates indicate that an increase in withdrawals of as much as 100 percent or more can take place before ground-water levels, by a persistent lowering, will begin to indicate that the annual replenishment is being exceeded. Title: Geology and ground-water resources of the Swan Lake-Yonna Valleys area, Klamath County, Oregon Author: Meyers, Joseph D. Year: 1952, 2007, 2005 Abstract The Swan Lake-Yonna Valleys area consists of two intermountain valleys with their subordinate side valleys adjoining slopes, and mountainous boundary ridges, In all the area covered is about 256 square miles but the essential agricultural sections are restricted to the floors of Swan Lake and Yonna valleys with their respective subsidiary extensions of Pine Flats and Alkali Lake flats, a valley-floor area totaling about 90 square miles The floors of Swan Lake Valley and Yonna Valley lie at an altitude of about U52OO feet but the mountainous boundary ridges rise generally to 6000 feeto Yonna Valley is largely drained to Lost River by Buck Creek but also in part to Alkali Lakeo Swan Lake Valley and Pine Flats have only internal drainage. The Swan Lake Valley floor is the top of a deep alluvial fill, while Yonna Valley floor is mainly an erosional surface sloping to lines of through drainage Precipitation is about lit inches annually on the valley floors 9 but must be much more, possibly 18 to 24 inches, on the higher parts of the drainage basins. The growing season is short and killing frosts do occur in late spring and early fall. The rock units forming the bedrock structure of the area are consolidated or semiconsolidated rocks of Tertiary age and are largely of volcanic-flow and volcanic-sedimentary originc They consist of three main elements, a lower lava-rock unit, a sedimentary and volcanic-sedimentary unit, and an upper lava-rock unito The unconsolidated deposits are the older alluvium of Quaternary (and in part of late-Tertiary) age and the younger alluvium of Quaternary age0 The bedrock is faulted and deformed particularly so along a northwest-southeast set of fault lines that have given a remarkable linearity to the topography. Unpublished records subject to revision Ground water occurs below a regional water table that slopes south-ward to the level of the Lost Rivero The upper lava rocks and the lower lava rocks contain the principal permeable zones that occur beneath the areao Breccia and other porous zones in those rocks in places yield water to wells at a rate as large as 35OOO gallons per minute with but 1 or 2 feet of drawdowno The economical construction of irrigation wells requires the determination of the best possible location at which those rocks may be tapped at shallow depth below the level of the water tableo The ground water in general relatively low in dissolved mineral matter and is but slightly to moderately hard and would be considered chemically satisfactory for most uaeso Irrigation is the principal use of the ground water in the area north of the Horsefly Irrigation Districto There 3? wells supplied about 6,000 acre-feet of water to about 3800 acres of land in 1950. Water-level records obtained since 19U8 and approximations of the probable annual recharge from precipitation indicate that the present withdrawals are considerably less than the annual increment of the ground-water recharge, Rough estimates indicate that an increase in withdrawals of as much as 100 percent or more can take place before ground-water levels, by a persistent lowering, will begin to indicate that the annual replenishment is being exceeded. Close

• 30. [Image] Hydrogeology and paleohydrology in the Williamson River basin, Klamath County, Oregon

  	Abstract An abstract of the thesis of Jeffrey Scott Conaway for the Master of Science in Geology presented December 8, 1999. Title: Hydrogeology and Paleohydrology in the Williamson River Basin, Klamath ...
  	Citation × Citation Citation Abstract Copy Title: Hydrogeology and paleohydrology in the Williamson River basin, Klamath County, Oregon Author: Conaway, Jeffrey Scott Year: 2000, 2008, 2005 Abstract An abstract of the thesis of Jeffrey Scott Conaway for the Master of Science in Geology presented December 8, 1999. Title: Hydrogeology and Paleohydrology in the Williamson River Basin, Klamath County, Oregon. Stress on the water resources of the Williamson River basin has led to their regulation to protect important habitat. Quantification of this resource is required for accurate regulation. A portion of this study is a hydrogeologic reconnaissance that suggests directions for future work. Measured discharge and deuterium isotope data from points above and below the Williamson River canyon indicate that the river receives 99% of its discharge from ground water during periods of low flow. The principle aquifer of the southern Klamath Marsh is a fractured basalt, while continental sediments that are up to 200 m thick provide high artesian yields south of the canyon. The disparity between high precipitation on the basin's western margin and the low and variable discharge of the Williamson River at the Kirk Sill suggests either the presence of a fault zone that interrupts the flow of ground water or deep flow paths that do not surface within Klamath Marsh. Three terraces line the eastern edge of Klamath Marsh at approximate elevations of 1380, 1385, and 1397 m. The lowest terrace is late Holocene and cut into marsh sediment and reworked deposits from the pyroclastic eruptions of Mount Mazama. The middle terrace is planed into bedrock and formed when Pleistocene Lake Chemult occupied this basin. The upper terrace, a strand line, is delineated by a slope break that separates reworked pyroclastic deposits from undisturbed pyroclastic fall. Formation of this terrace occurred when pyroclastic flows from the cataclysmic eruption of Mount Mazama formed a blockage in the Williamson River canyon. Resultant backflooding reworked pyroclastic deposits and rafted pumice up to an approximate elevation of 1400 m. The blockage failed catastrophically from overtopping, draining 5.7 x 109 m3 of water, scouring the canyon and producing an erratic boulder deposit at the mouth of the canyon. Upstream evidence of rapid draining includes linear scour channels incised in pyroclastic-flow deposits and scouring of the broad Pleistocene terrace. Paleohydraulic reconstruction of down stream flooding using a flow-competence equation and a physically based dam-break model yield a peak discharge of 1.3 x 104 m3 s"1. Title: Hydrogeology and paleohydrology in the Williamson River basin, Klamath County, Oregon Author: Conaway, Jeffrey Scott Year: 2000, 2008, 2005 Abstract An abstract of the thesis of Jeffrey Scott Conaway for the Master of Science in Geology presented December 8, 1999. Title: Hydrogeology and Paleohydrology in the Williamson River Basin, Klamath County, Oregon. Stress on the water resources of the Williamson River basin has led to their regulation to protect important habitat. Quantification of this resource is required for accurate regulation. A portion of this study is a hydrogeologic reconnaissance that suggests directions for future work. Measured discharge and deuterium isotope data from points above and below the Williamson River canyon indicate that the river receives 99% of its discharge from ground water during periods of low flow. The principle aquifer of the southern Klamath Marsh is a fractured basalt, while continental sediments that are up to 200 m thick provide high artesian yields south of the canyon. The disparity between high precipitation on the basin's western margin and the low and variable discharge of the Williamson River at the Kirk Sill suggests either the presence of a fault zone that interrupts the flow of ground water or deep flow paths that do not surface within Klamath Marsh. Three terraces line the eastern edge of Klamath Marsh at approximate elevations of 1380, 1385, and 1397 m. The lowest terrace is late Holocene and cut into marsh sediment and reworked deposits from the pyroclastic eruptions of Mount Mazama. The middle terrace is planed into bedrock and formed when Pleistocene Lake Chemult occupied this basin. The upper terrace, a strand line, is delineated by a slope break that separates reworked pyroclastic deposits from undisturbed pyroclastic fall. Formation of this terrace occurred when pyroclastic flows from the cataclysmic eruption of Mount Mazama formed a blockage in the Williamson River canyon. Resultant backflooding reworked pyroclastic deposits and rafted pumice up to an approximate elevation of 1400 m. The blockage failed catastrophically from overtopping, draining 5.7 x 109 m3 of water, scouring the canyon and producing an erratic boulder deposit at the mouth of the canyon. Upstream evidence of rapid draining includes linear scour channels incised in pyroclastic-flow deposits and scouring of the broad Pleistocene terrace. Paleohydraulic reconstruction of down stream flooding using a flow-competence equation and a physically based dam-break model yield a peak discharge of 1.3 x 104 m3 s"1. Close

• 31. [Article] Geology of the Breitenbush Hot Springs area, Cascade Range, Oregon

  The Breitenbush Hot Springs area lies on the boundary of folded middle to late Tertiary Western Cascade rocks and younger High Cascade rocks. Within the mapped area the Western Cascade rocks are represented ...

  Citation × Citation Citation Abstract Copy Title: Geology of the Breitenbush Hot Springs area, Cascade Range, Oregon Author: Clayton, Clifford Michael Year: 1976 The Breitenbush Hot Springs area lies on the boundary of folded middle to late Tertiary Western Cascade rocks and younger High Cascade rocks. Within the mapped area the Western Cascade rocks are represented by four formations. The Detroit Beds, a sequence of interstratified tuffaceous sandstone, mudflow breccia, and tuff, is overlain unconformably by the Breitenbush Tuff. The Breitenbush Tuff consists of three units of welded pumice-rich crystal-vitric ash-flow tuffs interbedded with tuffaceous sedimentary rocks. The Outerson Formation unconformably overlies the Breitenbush Tuff and consists primarily of basaltic lava and breccia. The Outerson Formation includes three localized members: a basal, glassy, aphanitic basalt, the Lake Leone Sediments, and the Outerson Tuff. The Outerson Formation is cut by a number of feeder dikes and plugs and is unconformably overlain by the Cheat Creek Sediments, composed of volcanic sedimentary rocks and a distinctive basaltic tuff. The Western Cascade formations total more than 1660 m {5500 ft) of strata and range from Oligocene to Pliocene in age. The High Cascade rocks are represented by two formations: the Triangulation Peak Volcanics of basalt and andesite lava and breccia, lying unconformably atop the Cheat Creek Sediments; and unconformably beneath the Collowash Volcanics, a series of thin basaltic lava flows and breccias. The Western and High Cascade rocks are covered extensively by surficial deposits, primarily glacial drift. The High Cascade formations are at least 840 m (2800 ft) thick, ranging in age from Pliocene to Pliestocene. The Western Cascade rocks have been folded and faulted in the Breitenbush Hot Springs area, and form the eastern limb of the north-trending Breitenbush Anticline. The folded rocks and the erosional unconformities between the rock units probably represent two local episodes of orogeny: one in early to middle Miocene and another in late Pliocene to Pleistocene time. The Outerson Formation represents a depositional sequence between the periods of uplift and deformation. Faulting accompanied the orogenic sequences. The primary volcanic landforms in the area have been destroyed by erosion but skeletal remains of High Cascade volcanoes are recognized. Stream erosion and glaciation are responsible for the present landforms. Breitenbush Hot Springs occurs, in part, along basaltic dikes which channel the water through impermeable Breitenbush Tuff. The dikes are believed to be associated with the Outerson basalts. The Hot Springs discharge upwards at 3400 l/min. (900 gpm) of water at temperatures up to 92°C (198°F). Title: Geology of the Breitenbush Hot Springs area, Cascade Range, Oregon Author: Clayton, Clifford Michael Year: 1976 The Breitenbush Hot Springs area lies on the boundary of folded middle to late Tertiary Western Cascade rocks and younger High Cascade rocks. Within the mapped area the Western Cascade rocks are represented by four formations. The Detroit Beds, a sequence of interstratified tuffaceous sandstone, mudflow breccia, and tuff, is overlain unconformably by the Breitenbush Tuff. The Breitenbush Tuff consists of three units of welded pumice-rich crystal-vitric ash-flow tuffs interbedded with tuffaceous sedimentary rocks. The Outerson Formation unconformably overlies the Breitenbush Tuff and consists primarily of basaltic lava and breccia. The Outerson Formation includes three localized members: a basal, glassy, aphanitic basalt, the Lake Leone Sediments, and the Outerson Tuff. The Outerson Formation is cut by a number of feeder dikes and plugs and is unconformably overlain by the Cheat Creek Sediments, composed of volcanic sedimentary rocks and a distinctive basaltic tuff. The Western Cascade formations total more than 1660 m {5500 ft) of strata and range from Oligocene to Pliocene in age. The High Cascade rocks are represented by two formations: the Triangulation Peak Volcanics of basalt and andesite lava and breccia, lying unconformably atop the Cheat Creek Sediments; and unconformably beneath the Collowash Volcanics, a series of thin basaltic lava flows and breccias. The Western and High Cascade rocks are covered extensively by surficial deposits, primarily glacial drift. The High Cascade formations are at least 840 m (2800 ft) thick, ranging in age from Pliocene to Pliestocene. The Western Cascade rocks have been folded and faulted in the Breitenbush Hot Springs area, and form the eastern limb of the north-trending Breitenbush Anticline. The folded rocks and the erosional unconformities between the rock units probably represent two local episodes of orogeny: one in early to middle Miocene and another in late Pliocene to Pleistocene time. The Outerson Formation represents a depositional sequence between the periods of uplift and deformation. Faulting accompanied the orogenic sequences. The primary volcanic landforms in the area have been destroyed by erosion but skeletal remains of High Cascade volcanoes are recognized. Stream erosion and glaciation are responsible for the present landforms. Breitenbush Hot Springs occurs, in part, along basaltic dikes which channel the water through impermeable Breitenbush Tuff. The dikes are believed to be associated with the Outerson basalts. The Hot Springs discharge upwards at 3400 l/min. (900 gpm) of water at temperatures up to 92°C (198°F). Close

• 32. [Article] Quaternary Chronology and Stratigraphy of Mickey Springs, Oregon

  Mickey Springs in the Alvord Desert, southeast Oregon, is analogous to other Basin and Range hydrothermal systems where the requisite conditions of heat source and permeable pathways are met through crustal ...

  Citation × Citation Citation Abstract Copy Title: Quaternary Chronology and Stratigraphy of Mickey Springs, Oregon Author: Mowbray, Leslie Allen Year: 2015 Mickey Springs in the Alvord Desert, southeast Oregon, is analogous to other Basin and Range hydrothermal systems where the requisite conditions of heat source and permeable pathways are met through crustal thinning due to normal faulting. This study examines the morphology and lifespan of near-surface spring features through use of ground penetrating radar, thermoluminescence (TL) dating, and elevation modeling. Duration of hydrothermal activity at Mickey Springs has not previously been determined, and age determinations of sinter at the site are conflicting. The reason for and timing of this change in silica saturation in the hydrothermal fluid has not been resolved. Three morphologies of silica sinter deposition have been identified at Mickey Springs. These are (1) well-sorted, fine-grained sandstone with ripple marks, cross beds and preserved root casts, to poorly-sorted conglomerate of primarily basalt clasts, both cemented by coeval silica deposition, (2) large depressions (12-32 m diameter) rimmed with sinter, characterized by fine silt and clay blanketing a sinter apron and infilling the central depression, and (3) quaquaversal sinter mounds identified by outcropping pool-edge sinter typically surrounding a shallow depression of loose sediment. Silica-cemented sandstone and conglomerate were the first features formed by coeval hydrothermal processes at the site, and were emplaced prior to 30 kya as suggested by structural and stratigraphic relationships. Structure between two interacting fault tips may have constrained the extent of silica cementation. By 30 kya, a left-stepping fault oriented roughly north/south further constrained the near-surface permeable zone. TL dates from sediment stratigraphically below and above sinter aprons around mounds and depressions (former spring vents) indicate sinter deposition between 30 and 20 kya. Location of these features was dictated by development of the left-stepping fault. As pluvial Lake Alvord filled at the end of the Pleistocene, lake sediment filled most vents, which were largely inactive, with fine-grained silt and clay. Today, hydrothermal activity persists in two modes: (1) The current high-temperature springs, steam vents and mudpots concentrated in a 50 x 50 m area south of the sinter mounds and depressions, and (2) scattered springs and steam vents that exploit previous permeable pathways that once provided the hydrothermal fluid which precipitated the sinter aprons. Currently there is no active silica sinter deposition at Mickey Springs. Structures and stratigraphic relationships identified through this study favor a transport-limited and structurally controlled model of fluid transport. Sinter deposition is determined to have occurred before the most recent highstand of pluvial Lake Alvord. A climate driven model, where groundwater recharge from pluvial Lake Alvord circulates to a deep heat source and enhances spring discharge, is not supported by these findings, as no evidence was found for sinter precipitation after the drying of the lake. Future studies of other hydrothermal systems in the Basin and Range may reveal that permeable pathways along local structures are the primary drivers in this region. Title: Quaternary Chronology and Stratigraphy of Mickey Springs, Oregon Author: Mowbray, Leslie Allen Year: 2015 Mickey Springs in the Alvord Desert, southeast Oregon, is analogous to other Basin and Range hydrothermal systems where the requisite conditions of heat source and permeable pathways are met through crustal thinning due to normal faulting. This study examines the morphology and lifespan of near-surface spring features through use of ground penetrating radar, thermoluminescence (TL) dating, and elevation modeling. Duration of hydrothermal activity at Mickey Springs has not previously been determined, and age determinations of sinter at the site are conflicting. The reason for and timing of this change in silica saturation in the hydrothermal fluid has not been resolved. Three morphologies of silica sinter deposition have been identified at Mickey Springs. These are (1) well-sorted, fine-grained sandstone with ripple marks, cross beds and preserved root casts, to poorly-sorted conglomerate of primarily basalt clasts, both cemented by coeval silica deposition, (2) large depressions (12-32 m diameter) rimmed with sinter, characterized by fine silt and clay blanketing a sinter apron and infilling the central depression, and (3) quaquaversal sinter mounds identified by outcropping pool-edge sinter typically surrounding a shallow depression of loose sediment. Silica-cemented sandstone and conglomerate were the first features formed by coeval hydrothermal processes at the site, and were emplaced prior to 30 kya as suggested by structural and stratigraphic relationships. Structure between two interacting fault tips may have constrained the extent of silica cementation. By 30 kya, a left-stepping fault oriented roughly north/south further constrained the near-surface permeable zone. TL dates from sediment stratigraphically below and above sinter aprons around mounds and depressions (former spring vents) indicate sinter deposition between 30 and 20 kya. Location of these features was dictated by development of the left-stepping fault. As pluvial Lake Alvord filled at the end of the Pleistocene, lake sediment filled most vents, which were largely inactive, with fine-grained silt and clay. Today, hydrothermal activity persists in two modes: (1) The current high-temperature springs, steam vents and mudpots concentrated in a 50 x 50 m area south of the sinter mounds and depressions, and (2) scattered springs and steam vents that exploit previous permeable pathways that once provided the hydrothermal fluid which precipitated the sinter aprons. Currently there is no active silica sinter deposition at Mickey Springs. Structures and stratigraphic relationships identified through this study favor a transport-limited and structurally controlled model of fluid transport. Sinter deposition is determined to have occurred before the most recent highstand of pluvial Lake Alvord. A climate driven model, where groundwater recharge from pluvial Lake Alvord circulates to a deep heat source and enhances spring discharge, is not supported by these findings, as no evidence was found for sinter precipitation after the drying of the lake. Future studies of other hydrothermal systems in the Basin and Range may reveal that permeable pathways along local structures are the primary drivers in this region. Close

• 33. [Article] Late Pleistocene and recent archaeology and geomorphology of the south shore of Harney Lake, Oregon

  The present study was a response to the discovery of two artifacts found in a ditch wall near Harney Lake, Oregon. These were lying on a buried lake floor that appeared to be of late Pleistocene or early ...

  Citation × Citation Citation Abstract Copy Title: Late Pleistocene and recent archaeology and geomorphology of the south shore of Harney Lake, Oregon Author: Gehr, Keith Donald Year: 1980 The present study was a response to the discovery of two artifacts found in a ditch wall near Harney Lake, Oregon. These were lying on a buried lake floor that appeared to be of late Pleistocene or early Recent age. Other sediments exposed in the ditch seemed to relate to at least some of the phases of the pluvial lake sequence in the Harney Basin. Three problems were considered: (1) the geomorphology and dating of the pluvial lake stillstands, (2) whether the original artifacts were part of a larger early site, and (3) whether there was any relationship between archaeological sites and geomorphic features in the area. These problems were approached in the field by stratigraphic mapping of exposed sediments and by an archaeological survey of a defined study area. Test excavations were made adjacent to the location of the original artifact discovery to search for other cultural material. Beachline records of four stillstands of Pluvial Lake Malheur are preserved in the exposed sediments. The youngest beachline is undated. Three others were 14C dated from associated fossil molluscs at 32,000, 9620 and 8680 B.P. At least in the case of the 8680 B.P. lake, the Harney Basin was filled to overflowing and was a part of the Columbia River system. The Voltage basalt flow, which dammed the outlet of the Basin in Malheur Gap, was in place by 32,000 years ago. There is no evidence for a diversion of the Basin outlet to Crane Gap following this event. Molluscan fossils and diatoms were used, along with soil texture analyses, to help identify and differentiate sedimentary deposits and to draw environmental inferences. Artifacts were found both on and beneath buried beach deposits of the 8680 B.P. lake. Four of the five sites in the study area were either on wave-cut terraces or other lakeshore features associated with this lake. Diagnostic artifacts are Lind Coulee points, crescents, basally ground leaf-shaped points, and what are apparently true blades. The sites seem to have been located to take advantage of shallow water littoral zone resources. Fish may have been an important dietary item of the early Harney Basin dwellers. Large salmonid vertebrae from fish in the 10 kg weight class are found on the playa. By using the relationship between landforms and elevations it may be possible to predict the general age class of other sites on the margin of the playas. Title: Late Pleistocene and recent archaeology and geomorphology of the south shore of Harney Lake, Oregon Author: Gehr, Keith Donald Year: 1980 The present study was a response to the discovery of two artifacts found in a ditch wall near Harney Lake, Oregon. These were lying on a buried lake floor that appeared to be of late Pleistocene or early Recent age. Other sediments exposed in the ditch seemed to relate to at least some of the phases of the pluvial lake sequence in the Harney Basin. Three problems were considered: (1) the geomorphology and dating of the pluvial lake stillstands, (2) whether the original artifacts were part of a larger early site, and (3) whether there was any relationship between archaeological sites and geomorphic features in the area. These problems were approached in the field by stratigraphic mapping of exposed sediments and by an archaeological survey of a defined study area. Test excavations were made adjacent to the location of the original artifact discovery to search for other cultural material. Beachline records of four stillstands of Pluvial Lake Malheur are preserved in the exposed sediments. The youngest beachline is undated. Three others were 14C dated from associated fossil molluscs at 32,000, 9620 and 8680 B.P. At least in the case of the 8680 B.P. lake, the Harney Basin was filled to overflowing and was a part of the Columbia River system. The Voltage basalt flow, which dammed the outlet of the Basin in Malheur Gap, was in place by 32,000 years ago. There is no evidence for a diversion of the Basin outlet to Crane Gap following this event. Molluscan fossils and diatoms were used, along with soil texture analyses, to help identify and differentiate sedimentary deposits and to draw environmental inferences. Artifacts were found both on and beneath buried beach deposits of the 8680 B.P. lake. Four of the five sites in the study area were either on wave-cut terraces or other lakeshore features associated with this lake. Diagnostic artifacts are Lind Coulee points, crescents, basally ground leaf-shaped points, and what are apparently true blades. The sites seem to have been located to take advantage of shallow water littoral zone resources. Fish may have been an important dietary item of the early Harney Basin dwellers. Large salmonid vertebrae from fish in the 10 kg weight class are found on the playa. By using the relationship between landforms and elevations it may be possible to predict the general age class of other sites on the margin of the playas. Close

• 34. [Article] Origins of Late- Pleistocene Coastal Dune Sheets, Magdalena and Guerrero Negro, from Continental Shelf Low-stand Supply (70-20 ka), under Conditions of Southeast Littoral- and Eolian-Sand Transport, in Baja California Sur, Mexico

  Shallow morpho-stratigraphic sections (n = 11) in each of two large coastal dune sheets including the Magdalena (7000 km2) and Guerrero Negro (8000 km2) dune sheets, from the Pacific Ocean side of Baja ...

  Citation × Citation Citation Abstract Copy Title: Origins of Late- Pleistocene Coastal Dune Sheets, Magdalena and Guerrero Negro, from Continental Shelf Low-stand Supply (70-20 ka), under Conditions of Southeast Littoral- and Eolian-Sand Transport, in Baja California Sur, Mexico Author: Peterson, Curt D., Murillo-Jiminez, Janette, Stock, Errol, Price, David M., Hostetler, Steve W., Percy, David Year: 2017 Shallow morpho-stratigraphic sections (n = 11) in each of two large coastal dune sheets including the Magdalena (7000 km2) and Guerrero Negro (8000 km2) dune sheets, from the Pacific Ocean side of Baja California Sur, Mexico, have been analyzed for dune deposit age. The shallow morpho-stratigraphic sections (∼2-10 m depth) include 11 new TL and 14C ages, and paleosol chronosequences, that differentiate cemented late Pleistocene dune deposits (20.7 ± 2.1 to 99.8 ± 9.4 ka) from uncemented Holocene dune deposits (0.7 ± 0.05 to at least 3.2 ± 0.3 ka). Large linear dune ridges (5-10 m in height) in the dune sheet interiors trend southeast and are generally of late Pleistocene age (∼70-20 ka). The late Pleistocene dune deposits reflect eolian transport of marine sand across the emerged continental shelf (30-50 km southeast distance) from low-stand paleo-shorelines (-100 ± 25 m elevation), which were locally oriented nearly orthogonal to modeled deep-water wave directions (∼300° TN). During the Holocene marine transgression, onshore and alongshore wave transport delivered remobilized shelf-sand deposits to the nearshore areas of the large dune sheets, building extensive barrier islands and sand spits. Submerged back-barrier lagoons generally precluded marine sand supply to dune sheet interiors in middle to late Holocene time, though exceptions occur along some ocean and lagoon shorelines. Reactivation of the late Pleistocene dune deposits in the dune sheet interiors lead to generally thin (1-3 m thickness), but widespread, covers of Holocene dune deposits (0.41 ± 0.05 to 10.5 ± 1.6 ka). Mechanical drilling will be required to penetrate indurated subsoil caliche layers to reach basal Pleistocene dune deposits. Title: Origins of Late- Pleistocene Coastal Dune Sheets, Magdalena and Guerrero Negro, from Continental Shelf Low-stand Supply (70-20 ka), under Conditions of Southeast Littoral- and Eolian-Sand Transport, in Baja California Sur, Mexico Author: Peterson, Curt D., Murillo-Jiminez, Janette, Stock, Errol, Price, David M., Hostetler, Steve W., Percy, David Year: 2017 Shallow morpho-stratigraphic sections (n = 11) in each of two large coastal dune sheets including the Magdalena (7000 km2) and Guerrero Negro (8000 km2) dune sheets, from the Pacific Ocean side of Baja California Sur, Mexico, have been analyzed for dune deposit age. The shallow morpho-stratigraphic sections (∼2-10 m depth) include 11 new TL and 14C ages, and paleosol chronosequences, that differentiate cemented late Pleistocene dune deposits (20.7 ± 2.1 to 99.8 ± 9.4 ka) from uncemented Holocene dune deposits (0.7 ± 0.05 to at least 3.2 ± 0.3 ka). Large linear dune ridges (5-10 m in height) in the dune sheet interiors trend southeast and are generally of late Pleistocene age (∼70-20 ka). The late Pleistocene dune deposits reflect eolian transport of marine sand across the emerged continental shelf (30-50 km southeast distance) from low-stand paleo-shorelines (-100 ± 25 m elevation), which were locally oriented nearly orthogonal to modeled deep-water wave directions (∼300° TN). During the Holocene marine transgression, onshore and alongshore wave transport delivered remobilized shelf-sand deposits to the nearshore areas of the large dune sheets, building extensive barrier islands and sand spits. Submerged back-barrier lagoons generally precluded marine sand supply to dune sheet interiors in middle to late Holocene time, though exceptions occur along some ocean and lagoon shorelines. Reactivation of the late Pleistocene dune deposits in the dune sheet interiors lead to generally thin (1-3 m thickness), but widespread, covers of Holocene dune deposits (0.41 ± 0.05 to 10.5 ± 1.6 ka). Mechanical drilling will be required to penetrate indurated subsoil caliche layers to reach basal Pleistocene dune deposits. Close

• 35. [Article] Coastal Eolian Sand-Ramp Development Related to Paleo-Sea-Level Changes during the Latest Pleistocene and Holocene (21–0 ka) in San Miguel Island, California, U.S.A.

  Coastal eolian sand ramps (5–130 m elevation) on the northern slope (windward) side of the small San Miguel Island (13 km in W-E length) range in age from late Pleistocene to modern time, though a major ...

  Citation × Citation Citation Abstract Copy Title: Coastal Eolian Sand-Ramp Development Related to Paleo-Sea-Level Changes during the Latest Pleistocene and Holocene (21–0 ka) in San Miguel Island, California, U.S.A. Author: Peterson, Curt D., Erlandson, Jon M., Stock, Errol, Hostetler, Steve W., Price, David M. Year: 2017 Coastal eolian sand ramps (5–130 m elevation) on the northern slope (windward) side of the small San Miguel Island (13 km in W-E length) range in age from late Pleistocene to modern time, though a major hiatus in sand-ramp growth occurred during the early Holocene marine transgression (16–9 ka). The Holocene sand ramps (1–5 m measured thicknesses) currently lack large dune forms, thereby representing deflated erosional remnants, locally covering thicker late Pleistocene sand-ramp deposits. The ramp sand was initially supplied from the adjacent island-shelf platform, extending about 20 km north of the present coastline. The sand-ramp deposits and interbedded loess soils were 14C dated using 112 samples from 32 archaeological sites and other geologic sections. Latest Pleistocene sand ramps (66–18 ka) were derived from across-shelf eolian sand transport during marine low stands. Shoreward wave transport supplied remobilized late Pleistocene sand from the inner shelf to Holocene beaches, where dominant NW winds supplied sand to the sand ramps. The onset dates of the sand-ramp deposition in San Miguel are 7.2 ± 1.5 ka (sample n = 14). The internal strata dates in the vertically accreting sand ramps are 3.4 ± 1.7 ka (n = 34). The sand ramps in San Miguel show wide-scale termination of sand supply in the latest Holocene time. The sand-ramp top dates or burial dates are 1.7 ± 0.9 ka (n = 28). The latest Holocene sand ramps are truncated along most of the island's northern coastline, indicating recent losses of nearshore sand reserves to onshore, alongshore, and, possibly, offshore sand sinks. The truncated sand ramps in San Miguel Island and in other sand-depleted marine coastlines provide warnings about future beach erosion and/or shoreline retreat from accelerated sea-level rise accompanying predicted global warming. Title: Coastal Eolian Sand-Ramp Development Related to Paleo-Sea-Level Changes during the Latest Pleistocene and Holocene (21–0 ka) in San Miguel Island, California, U.S.A. Author: Peterson, Curt D., Erlandson, Jon M., Stock, Errol, Hostetler, Steve W., Price, David M. Year: 2017 Coastal eolian sand ramps (5–130 m elevation) on the northern slope (windward) side of the small San Miguel Island (13 km in W-E length) range in age from late Pleistocene to modern time, though a major hiatus in sand-ramp growth occurred during the early Holocene marine transgression (16–9 ka). The Holocene sand ramps (1–5 m measured thicknesses) currently lack large dune forms, thereby representing deflated erosional remnants, locally covering thicker late Pleistocene sand-ramp deposits. The ramp sand was initially supplied from the adjacent island-shelf platform, extending about 20 km north of the present coastline. The sand-ramp deposits and interbedded loess soils were 14C dated using 112 samples from 32 archaeological sites and other geologic sections. Latest Pleistocene sand ramps (66–18 ka) were derived from across-shelf eolian sand transport during marine low stands. Shoreward wave transport supplied remobilized late Pleistocene sand from the inner shelf to Holocene beaches, where dominant NW winds supplied sand to the sand ramps. The onset dates of the sand-ramp deposition in San Miguel are 7.2 ± 1.5 ka (sample n = 14). The internal strata dates in the vertically accreting sand ramps are 3.4 ± 1.7 ka (n = 34). The sand ramps in San Miguel show wide-scale termination of sand supply in the latest Holocene time. The sand-ramp top dates or burial dates are 1.7 ± 0.9 ka (n = 28). The latest Holocene sand ramps are truncated along most of the island's northern coastline, indicating recent losses of nearshore sand reserves to onshore, alongshore, and, possibly, offshore sand sinks. The truncated sand ramps in San Miguel Island and in other sand-depleted marine coastlines provide warnings about future beach erosion and/or shoreline retreat from accelerated sea-level rise accompanying predicted global warming. Close

• 36. [Article] A multivariate test of evolutionary stasis in Homo sapiens

  In the past, efforts to prove or disprove stasis in hominids have relied upon univariate tests such as Students's t-test. Severe methodological and interpretive problems arise from the misapplication of ...

  Citation × Citation Citation Abstract Copy Title: A multivariate test of evolutionary stasis in Homo sapiens Author: Kleckner, Jon Geoffrey Year: 1989 In the past, efforts to prove or disprove stasis in hominids have relied upon univariate tests such as Students's t-test. Severe methodological and interpretive problems arise from the misapplication of univariate statistics to questions concerning variation in shape through time. These are questions best addressed using the multivariate approach of morphometrics. Eighteen cranial dimensions drawn from 33 mid and late Pleistocene Homo sapiens were examined using principal component analysis (PCA). PCA divided the sample into two distinct morphologies. Archaic Homo sapiens of the mid Pleistocene clustered with Wurm I neanderthals and apart from post Gottweig early anatomically modern Homo sapiens. ANOVA and Cluster analysis confirm the groups represent two different morphologies rather than a single spectrum of morphological change. These results support stasis rather than phyletic gradualism during this period of hominid evolution. Title: A multivariate test of evolutionary stasis in Homo sapiens Author: Kleckner, Jon Geoffrey Year: 1989 In the past, efforts to prove or disprove stasis in hominids have relied upon univariate tests such as Students's t-test. Severe methodological and interpretive problems arise from the misapplication of univariate statistics to questions concerning variation in shape through time. These are questions best addressed using the multivariate approach of morphometrics. Eighteen cranial dimensions drawn from 33 mid and late Pleistocene Homo sapiens were examined using principal component analysis (PCA). PCA divided the sample into two distinct morphologies. Archaic Homo sapiens of the mid Pleistocene clustered with Wurm I neanderthals and apart from post Gottweig early anatomically modern Homo sapiens. ANOVA and Cluster analysis confirm the groups represent two different morphologies rather than a single spectrum of morphological change. These results support stasis rather than phyletic gradualism during this period of hominid evolution. Close

• 37. [Article] The Bear Creek Site (45KI839), a Late Pleistocene–Holocene Transition Occupation in the Puget Sound Lowland, King County, Washington

  The Bear Creek site in Redmond, Washington, yields important information about settlement, subsistence, and technology in the Puget Lowland during the late Pleistocene–Holocene transition. The lithic assemblage ...

  Citation × Citation Citation Abstract Copy Title: The Bear Creek Site (45KI839), a Late Pleistocene–Holocene Transition Occupation in the Puget Sound Lowland, King County, Washington Author: Kopperl, Robert E., Taylor, Amanda K., Miss, Christian J., Ames, Kenneth M., Hodges, Charles M. Year: 2015 The Bear Creek site in Redmond, Washington, yields important information about settlement, subsistence, and technology in the Puget Lowland during the late Pleistocene–Holocene transition. The lithic assemblage is dominated by expedient flake technology, but also contains bifaces and retouched tools. Ongoing analyses focus on site formation, procurement strategies of lithic raw materials, production of flake tools, and technological comparisons of Bear Creek stemmed and concave-base points with other Paleoarchaic technologies of western North America Title: The Bear Creek Site (45KI839), a Late Pleistocene–Holocene Transition Occupation in the Puget Sound Lowland, King County, Washington Author: Kopperl, Robert E., Taylor, Amanda K., Miss, Christian J., Ames, Kenneth M., Hodges, Charles M. Year: 2015 The Bear Creek site in Redmond, Washington, yields important information about settlement, subsistence, and technology in the Puget Lowland during the late Pleistocene–Holocene transition. The lithic assemblage is dominated by expedient flake technology, but also contains bifaces and retouched tools. Ongoing analyses focus on site formation, procurement strategies of lithic raw materials, production of flake tools, and technological comparisons of Bear Creek stemmed and concave-base points with other Paleoarchaic technologies of western North America Close

• 38. [Article] Mapping of Unstable and Potentially Unstable Slopes in Sogne og Fjordane

  For the past three years NGU has worked on 25 unstable and potentially unstable rock slopes in Sogn og Fjordane. In addition Fjærlandsfjord, Hyenfjord and Årdalsvatnet were systematically mapped for deposits ...

  Citation × Citation Citation Abstract Copy Title: Mapping of Unstable and Potentially Unstable Slopes in Sogne og Fjordane Author: Hermanns, Reginald L., Fischer, Luzia, Oppikofer, Thierry, Bøhme, M., Dehls, John F., Henriksen, H., Booth, Adam M., Eilertsen, R., Longva, O., Eiken, Trond Year: 2011 For the past three years NGU has worked on 25 unstable and potentially unstable rock slopes in Sogn og Fjordane. In addition Fjærlandsfjord, Hyenfjord and Årdalsvatnet were systematically mapped for deposits of prehistoric and historic rock slope failures onshore and with help of a bathymetry. Mapping on land included structural mapping of ten sites by on-site field mapping and nine sites by remote structural mapping using terrestrial laser scanning technology (TLS). Field work also included periodic monitoring of 14 sites using differential Global Positioning Systems (dGPS) and TLS at 4 sites. Synthetic Aperture Radar was app lied for the entire county but slide velocities could only be mapped out at one locality at Osmundneset (Gloppen municipality). A large amount of work was carried out on the slope east of Flåm in the Aurland valley, and results have been reported separately (NGU 20 11 .025). Three large instabilities have been discovered or taken into the monitoring program. These are Osmundneset in Gloppen municipality, Skrednipa in Sogndal municipality, and the Ovris valley in Vik municipality. The largest movements with 1.5 cm horizontal and 1.5 cm vertical displacement were measured on the instability with a volume of approx. 1 Mm3 in Ovris valley. Opening of cracks has been measured at that site also in the 1960’s, 1970’s and 1980’s. Our data suggest a slight acceleration of this instability. Acceleration was also documented for a 100.000 m3 large instability called Lifjellet, although velocity of that site is less than half of the velocity of the block in Ovris valley. However at that site a collapse of a rockslope with a volume of 25.000 to 30.000 m3 occurred only 19 years ago. Installation of continuous monitoring and early-warning systems should be considered at both of those sites as well as at similar sites where relatively small instabilities that might fail without a long acceleration phase are positioned above settlements (Gråberget in Høyanger municipality). Similarly all other monitored instabilities in Sogn og Fjordane are in the order of mm/yr and not considered to be critical on a short term. However, periodic monitoring has to be continued. Cosmogenic nuclide dating (CN) has been applied to determine ages of rockslide deposits in Fjærlandfjord (Sogne municipality) and at the slope E of Flåm (Aurland community), resulting in Late Pleistocene and Holocene ages. CN dating has also applied to the sliding planes at Skjeringahaugane (Luste municipality). The results indicate that the movement initiated at the beginning of the Holocene and is progressive. Long term slip rates are in the same order of slip rates measured by dGPS. Title: Mapping of Unstable and Potentially Unstable Slopes in Sogne og Fjordane Author: Hermanns, Reginald L., Fischer, Luzia, Oppikofer, Thierry, Bøhme, M., Dehls, John F., Henriksen, H., Booth, Adam M., Eilertsen, R., Longva, O., Eiken, Trond Year: 2011 For the past three years NGU has worked on 25 unstable and potentially unstable rock slopes in Sogn og Fjordane. In addition Fjærlandsfjord, Hyenfjord and Årdalsvatnet were systematically mapped for deposits of prehistoric and historic rock slope failures onshore and with help of a bathymetry. Mapping on land included structural mapping of ten sites by on-site field mapping and nine sites by remote structural mapping using terrestrial laser scanning technology (TLS). Field work also included periodic monitoring of 14 sites using differential Global Positioning Systems (dGPS) and TLS at 4 sites. Synthetic Aperture Radar was app lied for the entire county but slide velocities could only be mapped out at one locality at Osmundneset (Gloppen municipality). A large amount of work was carried out on the slope east of Flåm in the Aurland valley, and results have been reported separately (NGU 20 11 .025). Three large instabilities have been discovered or taken into the monitoring program. These are Osmundneset in Gloppen municipality, Skrednipa in Sogndal municipality, and the Ovris valley in Vik municipality. The largest movements with 1.5 cm horizontal and 1.5 cm vertical displacement were measured on the instability with a volume of approx. 1 Mm3 in Ovris valley. Opening of cracks has been measured at that site also in the 1960’s, 1970’s and 1980’s. Our data suggest a slight acceleration of this instability. Acceleration was also documented for a 100.000 m3 large instability called Lifjellet, although velocity of that site is less than half of the velocity of the block in Ovris valley. However at that site a collapse of a rockslope with a volume of 25.000 to 30.000 m3 occurred only 19 years ago. Installation of continuous monitoring and early-warning systems should be considered at both of those sites as well as at similar sites where relatively small instabilities that might fail without a long acceleration phase are positioned above settlements (Gråberget in Høyanger municipality). Similarly all other monitored instabilities in Sogn og Fjordane are in the order of mm/yr and not considered to be critical on a short term. However, periodic monitoring has to be continued. Cosmogenic nuclide dating (CN) has been applied to determine ages of rockslide deposits in Fjærlandfjord (Sogne municipality) and at the slope E of Flåm (Aurland community), resulting in Late Pleistocene and Holocene ages. CN dating has also applied to the sliding planes at Skjeringahaugane (Luste municipality). The results indicate that the movement initiated at the beginning of the Holocene and is progressive. Long term slip rates are in the same order of slip rates measured by dGPS. Close

• 39. [Article] Late Pleistocene and Holocene Aged Glacial and Climatic Reconstructions in the Goat Rocks Wilderness, Washington, United States

  Eight glaciers, covering an area of 1.63 km2, reside on the northern and northeastern slopes of the Goat Rocks tallest peaks in the Cascades of central Washington. At least three glacial stands occurred ...

  Citation × Citation Citation Abstract Copy Title: Late Pleistocene and Holocene Aged Glacial and Climatic Reconstructions in the Goat Rocks Wilderness, Washington, United States Author: Heard, Joshua Andrews Year: 2012 Eight glaciers, covering an area of 1.63 km2, reside on the northern and northeastern slopes of the Goat Rocks tallest peaks in the Cascades of central Washington. At least three glacial stands occurred downstream from these glaciers. Closest to modern glacier termini are Little Ice Age (LIA) moraines that were deposited between 1870 and 1899 AD, according to the lichenometric analysis. They are characterized by sharp, minimally eroded crests, little to no soil cover, and minimal vegetation cover. Glacier reconstructions indicate that LIA glaciers covered 8.29 km2, 76% more area than modern ice coverage. The average LIA equilibrium line altitude (ELA) of 1995 ± 70 m is ~150 m below the average modern ELA of 2149 ± 76 m. To satisfy climate conditions at the LIA ELA, the winter snow accumulation must have been 8 to 43 cm greater and mean summer temperatures 0.2 to 1.3 ºC cooler than they are now. Late Pleistocene to early Holocene (LPEH) aged moraines are located between 100 and 400 m below the LIA deposits. They have degraded moraine crests, few surface boulders, and considerable vegetation and soil cover. Volcanic ashes indicate LPEH moraines were deposited before 1480 AD while morphometric data suggest deposition during the late Pleistocene or early Holocene. The average LPEH ELA of 1904 ± 110 m is ~ 240 m and ~90 m below the modern and LIA ELAs, respectively. The climate change necessary to maintain a glacier with an ELA at that elevation for LPEH conditions requires the winter accumulation to increase by 47 to 48 cm weq and the mean summer temperature to cool by 1.4 to 1.5 ºC. Last glacial maximum (LGM) moraines are located more than 30 km downstream from modern glacial termini. They are characterized by hummocky topography, rounded moraine crests, complete vegetation cover, and well developed soil cover. Moraine morphometry, soil characteristics, and distance from modern glacial termini indicate that deposition occurred at least 15 ka BP during an expansive cooling event, the last being the LGM. The LGM ELA of 1230 m is ~920 m below the modern ELA. The climate change necessary to maintain a glacier with an ELA at that elevation for LGM conditions requires the mean summer temperature to cool by 5.6 ºC with no change in precipitation. Title: Late Pleistocene and Holocene Aged Glacial and Climatic Reconstructions in the Goat Rocks Wilderness, Washington, United States Author: Heard, Joshua Andrews Year: 2012 Eight glaciers, covering an area of 1.63 km2, reside on the northern and northeastern slopes of the Goat Rocks tallest peaks in the Cascades of central Washington. At least three glacial stands occurred downstream from these glaciers. Closest to modern glacier termini are Little Ice Age (LIA) moraines that were deposited between 1870 and 1899 AD, according to the lichenometric analysis. They are characterized by sharp, minimally eroded crests, little to no soil cover, and minimal vegetation cover. Glacier reconstructions indicate that LIA glaciers covered 8.29 km2, 76% more area than modern ice coverage. The average LIA equilibrium line altitude (ELA) of 1995 ± 70 m is ~150 m below the average modern ELA of 2149 ± 76 m. To satisfy climate conditions at the LIA ELA, the winter snow accumulation must have been 8 to 43 cm greater and mean summer temperatures 0.2 to 1.3 ºC cooler than they are now. Late Pleistocene to early Holocene (LPEH) aged moraines are located between 100 and 400 m below the LIA deposits. They have degraded moraine crests, few surface boulders, and considerable vegetation and soil cover. Volcanic ashes indicate LPEH moraines were deposited before 1480 AD while morphometric data suggest deposition during the late Pleistocene or early Holocene. The average LPEH ELA of 1904 ± 110 m is ~ 240 m and ~90 m below the modern and LIA ELAs, respectively. The climate change necessary to maintain a glacier with an ELA at that elevation for LPEH conditions requires the winter accumulation to increase by 47 to 48 cm weq and the mean summer temperature to cool by 1.4 to 1.5 ºC. Last glacial maximum (LGM) moraines are located more than 30 km downstream from modern glacial termini. They are characterized by hummocky topography, rounded moraine crests, complete vegetation cover, and well developed soil cover. Moraine morphometry, soil characteristics, and distance from modern glacial termini indicate that deposition occurred at least 15 ka BP during an expansive cooling event, the last being the LGM. The LGM ELA of 1230 m is ~920 m below the modern ELA. The climate change necessary to maintain a glacier with an ELA at that elevation for LGM conditions requires the mean summer temperature to cool by 5.6 ºC with no change in precipitation. Close

• 40. [Article] Biochemical Description of a Lava Tube Lake in Southeast Oregon

  A Pleistocene lava tube cave in southeast Oregon has a seasonally fluctuating lake occupying the last 1200 to 2000 feet. Three endemic invertebrate species inhabit the lake: Kenkia rynchida Hyman; Asellus ...

  Citation × Citation Citation Abstract Copy Title: Biochemical Description of a Lava Tube Lake in Southeast Oregon Author: Palmer, John Edward Year: 1975 A Pleistocene lava tube cave in southeast Oregon has a seasonally fluctuating lake occupying the last 1200 to 2000 feet. Three endemic invertebrate species inhabit the lake: Kenkia rynchida Hyman; Asellus sp.; and stygobromus hubbsi. Shoemaker. Little is known however, about their environment. The purpose of this study was to describe various physical and chemical parameters of Malheur Cave Lake. Title: Biochemical Description of a Lava Tube Lake in Southeast Oregon Author: Palmer, John Edward Year: 1975 A Pleistocene lava tube cave in southeast Oregon has a seasonally fluctuating lake occupying the last 1200 to 2000 feet. Three endemic invertebrate species inhabit the lake: Kenkia rynchida Hyman; Asellus sp.; and stygobromus hubbsi. Shoemaker. Little is known however, about their environment. The purpose of this study was to describe various physical and chemical parameters of Malheur Cave Lake. Close

• 41. [Article] Chronology and Ecology of Late Pleistocene Megafauna in the Northern Willamette Valley, Oregon

  This study is an investigation of the timing of extinction of late Pleistocene, large bodied mammalian herbivores (megafauna) and of the environment in which they lived. The demise of the megafauna near ...

  Citation × Citation Citation Abstract Copy Title: Chronology and Ecology of Late Pleistocene Megafauna in the Northern Willamette Valley, Oregon Author: Gilmour, Daniel McGowan Year: 2011 This study is an investigation of the timing of extinction of late Pleistocene, large bodied mammalian herbivores (megafauna) and of the environment in which they lived. The demise of the megafauna near the end of the Pleistocene remains unexplained. Owing to potential human involvement in the extinctions, archaeologists have been particularly concerned to understand the causes for faunal losses. Our current lack of understanding of the timing and the causes of the extinctions in North America may result from a deficiency in understanding the histories of each individual species of extinct animal on a local level. Detailed regional chronologies of fauna are necessary for comparison with paleoenvironmental and archaeological data to help sort out causes for extinction. The Willamette Valley of western Oregon has long been noted for finds of megafauna, though records have not been synthesized since the early 20th century and these materials have remained largely unstudied. In this thesis, I first create a catalog of extinct megafauna recovered from the Willamette Valley. Next, using material from the northern valley, I employ AMS radiocarbon dating, stable isotope δ¹³C and δ¹⁵N analyses, and gross inferences based on the dietary specializations and habitat preferences of taxa in order to reconstruct environments and to develop a local chronology of events that is then arrayed against archaeological and paleoenvironmental data. The results of this study indicate that megafaunal populations in the northern Willamette Valley were contemporaneous with the earliest known human populations of the Pacific Northwest, as well as later populations associated with the Clovis Paleoindian Horizon. Consistent with the overkill hypothesis, radiocarbon ages span the length of the Clovis window, but no ages are younger than Clovis. Moreover, all radiocarbon ages are older than or contemporaneous to the onset of the Younger Dryas Stadial. No age ranges fall exclusively within the Younger Dryas. Comparison of megafaunal ages and paleoenvironmental records support the view that climate change contributed to local animal population declines. Prior to ~13,000 cal BP, the Willamette Valley was an open environment; herbivores mainly consumed C₃ vegetation. The timing of the loss of megafauna coincides with increased forested conditions as indicated by regional paleoenvironmental reconstruction. As the timing of megafaunal decline correlates with Clovis, the onset of the Younger Dryas, and increased forested conditions, it is not possible with the data currently available to distinguish the cause of extinction in the Willamette Valley. The age ranges of the fauna coupled with taphonomic and geologic context indicate that the fauna are autochthonous to the Willamette Valley; they do not represent ice rafted carcasses or isolated skeletal elements transported from elsewhere during late Pleistocene glacial outburst floods. Title: Chronology and Ecology of Late Pleistocene Megafauna in the Northern Willamette Valley, Oregon Author: Gilmour, Daniel McGowan Year: 2011 This study is an investigation of the timing of extinction of late Pleistocene, large bodied mammalian herbivores (megafauna) and of the environment in which they lived. The demise of the megafauna near the end of the Pleistocene remains unexplained. Owing to potential human involvement in the extinctions, archaeologists have been particularly concerned to understand the causes for faunal losses. Our current lack of understanding of the timing and the causes of the extinctions in North America may result from a deficiency in understanding the histories of each individual species of extinct animal on a local level. Detailed regional chronologies of fauna are necessary for comparison with paleoenvironmental and archaeological data to help sort out causes for extinction. The Willamette Valley of western Oregon has long been noted for finds of megafauna, though records have not been synthesized since the early 20th century and these materials have remained largely unstudied. In this thesis, I first create a catalog of extinct megafauna recovered from the Willamette Valley. Next, using material from the northern valley, I employ AMS radiocarbon dating, stable isotope δ¹³C and δ¹⁵N analyses, and gross inferences based on the dietary specializations and habitat preferences of taxa in order to reconstruct environments and to develop a local chronology of events that is then arrayed against archaeological and paleoenvironmental data. The results of this study indicate that megafaunal populations in the northern Willamette Valley were contemporaneous with the earliest known human populations of the Pacific Northwest, as well as later populations associated with the Clovis Paleoindian Horizon. Consistent with the overkill hypothesis, radiocarbon ages span the length of the Clovis window, but no ages are younger than Clovis. Moreover, all radiocarbon ages are older than or contemporaneous to the onset of the Younger Dryas Stadial. No age ranges fall exclusively within the Younger Dryas. Comparison of megafaunal ages and paleoenvironmental records support the view that climate change contributed to local animal population declines. Prior to ~13,000 cal BP, the Willamette Valley was an open environment; herbivores mainly consumed C₃ vegetation. The timing of the loss of megafauna coincides with increased forested conditions as indicated by regional paleoenvironmental reconstruction. As the timing of megafaunal decline correlates with Clovis, the onset of the Younger Dryas, and increased forested conditions, it is not possible with the data currently available to distinguish the cause of extinction in the Willamette Valley. The age ranges of the fauna coupled with taphonomic and geologic context indicate that the fauna are autochthonous to the Willamette Valley; they do not represent ice rafted carcasses or isolated skeletal elements transported from elsewhere during late Pleistocene glacial outburst floods. Close

• 42. [Article] Hydrogeologic Investigation of the Klamath Marsh, Klamath County, Oregon

  Klamath Marsh is a wetland complex that lies in the rain shadow of the Cascade Range in the Williamson River sub-basin of the Klamath Basin. The marsh lies directly east of Crater Lake in an area inundated ...

  Citation × Citation Citation Abstract Copy Title: Hydrogeologic Investigation of the Klamath Marsh, Klamath County, Oregon Author: Melady, Jason Michael Year: 2002 Klamath Marsh is a wetland complex that lies in the rain shadow of the Cascade Range in the Williamson River sub-basin of the Klamath Basin. The marsh lies directly east of Crater Lake in an area inundated by pyroclastic-flow and -fall deposits from the Holocene eruptions of Mount Mazama. The physical characteristics of rocks of Pleistocene versus Pliocene age combined with NNW -striking fault systems divide the Williamson River basin into two distinct hydrogeologic regimes. The northwestern regime includes the east slope of the Cascades and consists of at least 150 m of interbedded sand, gravel, and stacks (15 to 45 m) of thin (3-5 m) and vesiculated basalt lava flows. Mean annual precipitation ranges from 150 cm near the crest of the Cascades to 50 cm near Klamath Marsh. Moderate to high yield (100 to 4000 gpm) water wells, springs and flowing wells suggest high permeability and ground water potential. The southeastern regime is underlain by Pliocene pyroclastic flows (∼ 40 m) and lava flows (>30 m). Mean annual precipitation ranges from 70 cm in the highlands to 50 cm in the lowlands. Low-yield (20-100 gpm) water wells and perched unconfined aquifers in Holocene pumice deposits suggest low permeability and low ground water potential in areas underlain by the pyroclastic flows. Volumetric analysis of inflows and outflows in Klamath Marsh for 2000 indicates approximately 86% of inflow is from groundwater and 14% from surface water, with nearly 200 x 10⁶ m³ of water removed by evapotranspiration Title: Hydrogeologic Investigation of the Klamath Marsh, Klamath County, Oregon Author: Melady, Jason Michael Year: 2002 Klamath Marsh is a wetland complex that lies in the rain shadow of the Cascade Range in the Williamson River sub-basin of the Klamath Basin. The marsh lies directly east of Crater Lake in an area inundated by pyroclastic-flow and -fall deposits from the Holocene eruptions of Mount Mazama. The physical characteristics of rocks of Pleistocene versus Pliocene age combined with NNW -striking fault systems divide the Williamson River basin into two distinct hydrogeologic regimes. The northwestern regime includes the east slope of the Cascades and consists of at least 150 m of interbedded sand, gravel, and stacks (15 to 45 m) of thin (3-5 m) and vesiculated basalt lava flows. Mean annual precipitation ranges from 150 cm near the crest of the Cascades to 50 cm near Klamath Marsh. Moderate to high yield (100 to 4000 gpm) water wells, springs and flowing wells suggest high permeability and ground water potential. The southeastern regime is underlain by Pliocene pyroclastic flows (∼ 40 m) and lava flows (>30 m). Mean annual precipitation ranges from 70 cm in the highlands to 50 cm in the lowlands. Low-yield (20-100 gpm) water wells and perched unconfined aquifers in Holocene pumice deposits suggest low permeability and low ground water potential in areas underlain by the pyroclastic flows. Volumetric analysis of inflows and outflows in Klamath Marsh for 2000 indicates approximately 86% of inflow is from groundwater and 14% from surface water, with nearly 200 x 10⁶ m³ of water removed by evapotranspiration Close

• 43. [Article] Chronology and Ecology of Late Pleistocene Megafauna in the Northern Willamette Valley, Oregon

  Since the mid-19th century, western Oregon's Willamette Valley has been a source of remains from a wide variety of extinct megafauna. Few of these have been previously described or dated, but new chronologic ...

  Citation × Citation Citation Abstract Copy Title: Chronology and Ecology of Late Pleistocene Megafauna in the Northern Willamette Valley, Oregon Author: Gilmour, Daniel McGowan, Butler, Virginia L., O'Conner, Jim E., Byrd Davis, Edward, Culleton, Brendan J., Kennett, Douglas J., Hodgins, Gregory Year: 2014 Since the mid-19th century, western Oregon's Willamette Valley has been a source of remains from a wide variety of extinct megafauna. Few of these have been previously described or dated, but new chronologic and isotopic analyses in conjunction with updated evaluations of stratigraphic context provide substantial new information on the species present, timing of losses, and paleoenvironmental conditions. Using subfossil material from the northern valley, we use AMS radiocarbon dating, stable isotope (δ13C and δ15N) analyses, and taxonomic dietary specialization and habitat preferences to reconstruct environments and to develop a local chronology of events that we then compare with continental and regional archaeological and paleoenvironmental data. Analysis of twelve bone specimens demonstrates the presence of bison, mammoth, horse, sloth, and mastodon from ~15,000–13,000 cal yr BP. The latest ages coincide with changing regional climate corresponding to the onset of the Younger Dryas. It is suggested that cooling conditions led to increased forest cover, and, along with river aggradation, reduced the area of preferred habitat for the larger bodied herbivores, which contributed to the demise of local megafauna. Archaeological evidence for megafauna–human interactions in the Pacific Northwest is scarce, limiting our ability to address the human role in causing extinction. Title: Chronology and Ecology of Late Pleistocene Megafauna in the Northern Willamette Valley, Oregon Author: Gilmour, Daniel McGowan, Butler, Virginia L., O'Conner, Jim E., Byrd Davis, Edward, Culleton, Brendan J., Kennett, Douglas J., Hodgins, Gregory Year: 2014 Since the mid-19th century, western Oregon's Willamette Valley has been a source of remains from a wide variety of extinct megafauna. Few of these have been previously described or dated, but new chronologic and isotopic analyses in conjunction with updated evaluations of stratigraphic context provide substantial new information on the species present, timing of losses, and paleoenvironmental conditions. Using subfossil material from the northern valley, we use AMS radiocarbon dating, stable isotope (δ13C and δ15N) analyses, and taxonomic dietary specialization and habitat preferences to reconstruct environments and to develop a local chronology of events that we then compare with continental and regional archaeological and paleoenvironmental data. Analysis of twelve bone specimens demonstrates the presence of bison, mammoth, horse, sloth, and mastodon from ~15,000–13,000 cal yr BP. The latest ages coincide with changing regional climate corresponding to the onset of the Younger Dryas. It is suggested that cooling conditions led to increased forest cover, and, along with river aggradation, reduced the area of preferred habitat for the larger bodied herbivores, which contributed to the demise of local megafauna. Archaeological evidence for megafauna–human interactions in the Pacific Northwest is scarce, limiting our ability to address the human role in causing extinction. Close

• 44. [Article] A Characterization of Lake Abert Tufa Mounds Lake Abert, Oregon

  A series of tufa mounds is found within the northern basin of Lake Abert, located within southeastern Oregon. The mounds have been divided into 3 main groups and 1 sub-group (A1, A2, B, and C) based upon ...

  Citation × Citation Citation Abstract Copy Title: A Characterization of Lake Abert Tufa Mounds Lake Abert, Oregon Author: Bartruff, Anthony Lynn Year: 2013 A series of tufa mounds is found within the northern basin of Lake Abert, located within southeastern Oregon. The mounds have been divided into 3 main groups and 1 sub-group (A1, A2, B, and C) based upon spatial and textural considerations. Mound groups appear at two different elevations: the 1310 meter elevation (Groups A2, B, and C), and the 1318 meter elevation (Group A1). Published carbon age dating of the Lake Abert 1325 meter strandline and the 1310 meter strandline indicates that the mounds were formed during the Late Pleistocene/Early Holocene. Facies analysis and mineralogical analysis of the mounds indicates that the mounds were primarily formed subaqueously during a lake regression, supporting oxygen isotope data from previous researchers. Magnetometer data within Groups A1 and A2 suggests that the mounds are associated with a series of magnetic lows which are oriented in joint sets (NW-SE, and N-S) which match the orientation of faulting within the region. While there appears to be another early mound building episode, no direct evidence confirms this. Title: A Characterization of Lake Abert Tufa Mounds Lake Abert, Oregon Author: Bartruff, Anthony Lynn Year: 2013 A series of tufa mounds is found within the northern basin of Lake Abert, located within southeastern Oregon. The mounds have been divided into 3 main groups and 1 sub-group (A1, A2, B, and C) based upon spatial and textural considerations. Mound groups appear at two different elevations: the 1310 meter elevation (Groups A2, B, and C), and the 1318 meter elevation (Group A1). Published carbon age dating of the Lake Abert 1325 meter strandline and the 1310 meter strandline indicates that the mounds were formed during the Late Pleistocene/Early Holocene. Facies analysis and mineralogical analysis of the mounds indicates that the mounds were primarily formed subaqueously during a lake regression, supporting oxygen isotope data from previous researchers. Magnetometer data within Groups A1 and A2 suggests that the mounds are associated with a series of magnetic lows which are oriented in joint sets (NW-SE, and N-S) which match the orientation of faulting within the region. While there appears to be another early mound building episode, no direct evidence confirms this. Close

• 45. [Article] Ancient Cataclysmic Floods in the Pacific Northwest: Ancestors to the Missoula Floods

  Ancient Cataclysmic Floods were the Ice Age Floods that left erosional and depositional features and preceded the Missoula Floods (15-18,000 ka) in the Pacific Northwest of the United States (Allen et ...

  Citation × Citation Citation Abstract Copy Title: Ancient Cataclysmic Floods in the Pacific Northwest: Ancestors to the Missoula Floods Author: Medley, Erica Year: 2012 Ancient Cataclysmic Floods were the Ice Age Floods that left erosional and depositional features and preceded the Missoula Floods (15-18,000 ka) in the Pacific Northwest of the United States (Allen et al., 2009). All previously studied ancient sites were visited (14) and new sites (11) were found; four Missoula Flood quarries were also visited; a total of 29 sites were studied in this thesis. The use of calcrete paleosols to provide relative age dates for flood deposits was analyzed in this thesis. Missoula Flood gravel pits were sampled in order to examine the degree of calcrete development in flood deposits of known ages. All of the Missoula Flood deposits tested contain Stage 1 calcrete soil development. Calcrete paleosols at sites with evidence for older floods were all analyzed. Eight sites have paleosols with Stage II development (3-12% CaCO3): Rulo Outcrop, Potholes Coulee, Leslie Road, Benge, E. Callaway Road, Collier Coulee, Palouse, and Connell. Five sites have paleosols with Stage II+ development (12-17% CaCO3): Brown Road, Leslie Road, Benge, Reese Coulee, and Connell. Fourteen sites have paleosols with Stage III development (17-35% CaCO3): The Dalles, Rulo Outcrop, Winans Road 1, Poplar Heights, Yakima Bluffs, Canal Outcrop, Othello Canal, Reese Coulee, Potholes Coulee, E. Callaway Road, Frenchmen Coulee, Macall, Ritzville, and East Connell. One site has a paleosol with Stage III+ development (35-50% CaCO3): Othello Canal. Ancient Cataclysmic flooding initiated in the Early Pleistocene, at least 1.5 Ma. Sixteen field sites show evidence for Early Pleistocene flooding, preserved in all six provinces: Othello Channels, Columbia River Gorge, Cheney-Palouse Scabland, Quincy Basin, Pasco Basin, and the Walla Walla Valley. There are 26 field sites with evidence for Middle Pleistocene flooding, present in all regions except Othello Channels. Eleven of those 26 sites also show evidence for Early Pleistocene floods. Evidence for Early and Middle Pleistocene floods is present over a wide distribution of elevations from 117 to 524 meters. Title: Ancient Cataclysmic Floods in the Pacific Northwest: Ancestors to the Missoula Floods Author: Medley, Erica Year: 2012 Ancient Cataclysmic Floods were the Ice Age Floods that left erosional and depositional features and preceded the Missoula Floods (15-18,000 ka) in the Pacific Northwest of the United States (Allen et al., 2009). All previously studied ancient sites were visited (14) and new sites (11) were found; four Missoula Flood quarries were also visited; a total of 29 sites were studied in this thesis. The use of calcrete paleosols to provide relative age dates for flood deposits was analyzed in this thesis. Missoula Flood gravel pits were sampled in order to examine the degree of calcrete development in flood deposits of known ages. All of the Missoula Flood deposits tested contain Stage 1 calcrete soil development. Calcrete paleosols at sites with evidence for older floods were all analyzed. Eight sites have paleosols with Stage II development (3-12% CaCO3): Rulo Outcrop, Potholes Coulee, Leslie Road, Benge, E. Callaway Road, Collier Coulee, Palouse, and Connell. Five sites have paleosols with Stage II+ development (12-17% CaCO3): Brown Road, Leslie Road, Benge, Reese Coulee, and Connell. Fourteen sites have paleosols with Stage III development (17-35% CaCO3): The Dalles, Rulo Outcrop, Winans Road 1, Poplar Heights, Yakima Bluffs, Canal Outcrop, Othello Canal, Reese Coulee, Potholes Coulee, E. Callaway Road, Frenchmen Coulee, Macall, Ritzville, and East Connell. One site has a paleosol with Stage III+ development (35-50% CaCO3): Othello Canal. Ancient Cataclysmic flooding initiated in the Early Pleistocene, at least 1.5 Ma. Sixteen field sites show evidence for Early Pleistocene flooding, preserved in all six provinces: Othello Channels, Columbia River Gorge, Cheney-Palouse Scabland, Quincy Basin, Pasco Basin, and the Walla Walla Valley. There are 26 field sites with evidence for Middle Pleistocene flooding, present in all regions except Othello Channels. Eleven of those 26 sites also show evidence for Early Pleistocene floods. Evidence for Early and Middle Pleistocene floods is present over a wide distribution of elevations from 117 to 524 meters. Close

• 46. [Article] Accommodation Space Controls on the Latest Pleistocene and Holocene (16–0 ka) Sediment Size and Bypassing in the Lower Columbia River Valley: A Large Fluvial–Tidal System in Oregon and Washington, USA

  In this study, we establish the roles that increasing basin accommodation space have on sediment size and bypassing in the transgressive fill (16–0 ka) in the submerged Lower Columbia River Valley (LCRV). ...

  Citation × Citation Citation Abstract Copy Title: Accommodation Space Controls on the Latest Pleistocene and Holocene (16–0 ka) Sediment Size and Bypassing in the Lower Columbia River Valley: A Large Fluvial–Tidal System in Oregon and Washington, USA Author: Peterson, Curt D. Year: 2013 In this study, we establish the roles that increasing basin accommodation space have on sediment size and bypassing in the transgressive fill (16–0 ka) in the submerged Lower Columbia River Valley (LCRV). The antecedent forearc valley (225 km in length, 4–8 km in width, and 60–115 m in axial valley depth) is characterized by high sediment supply rates (10–15 million t y-1) but no delta at its mouth to the Pacific Ocean. Core sample sediment textures (N ¼ 1600) are analyzed from 3000 m of borehole sections in 58 representative boreholes to characterize the ancestral valley fill: 57% sand, 17% muddy sand, 12% sandy mud, and 14% mud (total fill volume¼77 km3). Decreasing mud endmember texture from between 30 and 60% (early Holocene) to 18% (late Holocene) is directly related to (1) declining rates of increasing basin accommodation space and (2) increasing sediment bypassing through the LCRV. Both conditions result from decreasing rates of sea level rise (15.0–1.5 mm y-1) in Holocene time. The overall coarsening of sediments, both upvalley and upsection, is controlled by declining rates of increasing basin accommodation space (5.66 million–0.57 million m3 y-1) during middle to late Holocene time. Differences between middle and late Holocene sediment accumulation rates yield bedload bypassing rates of 5– 6 million m3 y-1, under assumed conditions of constant sediment supply rates in middle to late Holocene time. Title: Accommodation Space Controls on the Latest Pleistocene and Holocene (16–0 ka) Sediment Size and Bypassing in the Lower Columbia River Valley: A Large Fluvial–Tidal System in Oregon and Washington, USA Author: Peterson, Curt D. Year: 2013 In this study, we establish the roles that increasing basin accommodation space have on sediment size and bypassing in the transgressive fill (16–0 ka) in the submerged Lower Columbia River Valley (LCRV). The antecedent forearc valley (225 km in length, 4–8 km in width, and 60–115 m in axial valley depth) is characterized by high sediment supply rates (10–15 million t y-1) but no delta at its mouth to the Pacific Ocean. Core sample sediment textures (N ¼ 1600) are analyzed from 3000 m of borehole sections in 58 representative boreholes to characterize the ancestral valley fill: 57% sand, 17% muddy sand, 12% sandy mud, and 14% mud (total fill volume¼77 km3). Decreasing mud endmember texture from between 30 and 60% (early Holocene) to 18% (late Holocene) is directly related to (1) declining rates of increasing basin accommodation space and (2) increasing sediment bypassing through the LCRV. Both conditions result from decreasing rates of sea level rise (15.0–1.5 mm y-1) in Holocene time. The overall coarsening of sediments, both upvalley and upsection, is controlled by declining rates of increasing basin accommodation space (5.66 million–0.57 million m3 y-1) during middle to late Holocene time. Differences between middle and late Holocene sediment accumulation rates yield bedload bypassing rates of 5– 6 million m3 y-1, under assumed conditions of constant sediment supply rates in middle to late Holocene time. Close

• 47. [Article] Groundwater Surface Trends in the North Florence Dunal Aquifer, Oregon Coast, USA

  The North Florence Dunal Aquifer is the only feasible source for drinking water for the coastal city of Florence, Oregon and Florence's Urban Growth Boundary. High infiltration rates and a shallow groundwater ...

  Citation × Citation Citation Abstract Copy Title: Groundwater Surface Trends in the North Florence Dunal Aquifer, Oregon Coast, USA Author: Doliber, Sarah Rebecca Year: 2012 The North Florence Dunal Aquifer is the only feasible source for drinking water for the coastal city of Florence, Oregon and Florence's Urban Growth Boundary. High infiltration rates and a shallow groundwater table leave the aquifer highly susceptible to contamination from septic tank effluent, storm runoff, chemical fertilizers and recreational ATV use throughout the dunes. Public interest in the quality and quantity of the aquifer water has been sparked since the City of Florence received a grant from the Environmental Protection Agency for a watershed protection and restoration project. Delineation of the shallow groundwater surface and its relationship to the surface water bodies within the dunes is crucial in protecting this drinking water source from contamination. This thesis project created a GIS representation of the shallow groundwater elevation and associated prediction error map. Surface water bodies were confirmed as window lakes into the dunal aquifer and no signs of perched aquifer conditions were observed between Holocene and Pleistocene dunes. Ground Penetrating Radar, well data provided by the city of Florence and LiDAR were the primary sources for data collection. Title: Groundwater Surface Trends in the North Florence Dunal Aquifer, Oregon Coast, USA Author: Doliber, Sarah Rebecca Year: 2012 The North Florence Dunal Aquifer is the only feasible source for drinking water for the coastal city of Florence, Oregon and Florence's Urban Growth Boundary. High infiltration rates and a shallow groundwater table leave the aquifer highly susceptible to contamination from septic tank effluent, storm runoff, chemical fertilizers and recreational ATV use throughout the dunes. Public interest in the quality and quantity of the aquifer water has been sparked since the City of Florence received a grant from the Environmental Protection Agency for a watershed protection and restoration project. Delineation of the shallow groundwater surface and its relationship to the surface water bodies within the dunes is crucial in protecting this drinking water source from contamination. This thesis project created a GIS representation of the shallow groundwater elevation and associated prediction error map. Surface water bodies were confirmed as window lakes into the dunal aquifer and no signs of perched aquifer conditions were observed between Holocene and Pleistocene dunes. Ground Penetrating Radar, well data provided by the city of Florence and LiDAR were the primary sources for data collection. Close

• 48. [Article] Origins of Quaternary Coastal Dune Sheets in San Francisco and Monterey Bay, Central California Coast, U.S.A.: Reflecting Contrasts in Shelf Depocenters and Coastal Neotectonics

  The San Francisco and Monterey Bay coastal dune sheets derive from similar origins in the central California coast but differ substantially in size (respectively, ~400 and ~900 km2) and age (respectively, ...

  Citation × Citation Citation Abstract Copy Title: Origins of Quaternary Coastal Dune Sheets in San Francisco and Monterey Bay, Central California Coast, U.S.A.: Reflecting Contrasts in Shelf Depocenters and Coastal Neotectonics Author: Peterson, Curt D., Stock, Errol, Meyer, Jack, Kaijankoski, Philip, Price, David M. Year: 2015 The San Francisco and Monterey Bay coastal dune sheets derive from similar origins in the central California coast but differ substantially in size (respectively, ~400 and ~900 km2) and age (respectively, 1.0 Ma). The San Francisco dune sheet is restricted to a short alongshore interval (km) within a relatively straight coastline (150 km in length) that borders a broad shelf (~40 km in width). The Monterey Bay dune sheet is restricted to the Monterey Bay embayment (41 km alongshore length). The embayment includes a very narrow shelf (3–15 km in width), which is dissected by the Monterey Submarine Canyon. Generally low onshore topographic relief (elevation) likely enhanced inland transgression of Late Pleistocene dune fields in both the San Francisco and Monterey Bay areas. The locations of the dune sheets are directly related to sand accumulations in marine low-stand depocenters that supplied sand to the adjacent dune fields by eolian transport across the emerged inner shelves. The San Francisco shelf depocenter is apparently localized at a midshelf bight (−50 to −100 m elevation) that extends 25 km (east–west) offshore of a paleoriver mouth of a major river system, the Sacramento–San Joaquin River. The Monterey Bay shelf depocenter is bounded alongshore by major headlands and converging paleoshorelines (−30 to −90 m elevation) that effectively trapped littoral sand from small coastal drainages, primarily the Salinas River. High vertical rates of neotectonic deformation in the San Francisco dune sheet (0.4–1.0 mm y−1) limited dune sheet longevity and deposit thickness (5–35 m). Low uplift rates (~0.1 mm y−1) in the central Monterey Bay dune sheet permitted deposit accumulations of up to 250 m thickness. The differences in dune sheet extent, thickness, and age resulted from key differences in localized shelf accommodation space and coastal neotectonic vertical movements. Title: Origins of Quaternary Coastal Dune Sheets in San Francisco and Monterey Bay, Central California Coast, U.S.A.: Reflecting Contrasts in Shelf Depocenters and Coastal Neotectonics Author: Peterson, Curt D., Stock, Errol, Meyer, Jack, Kaijankoski, Philip, Price, David M. Year: 2015 The San Francisco and Monterey Bay coastal dune sheets derive from similar origins in the central California coast but differ substantially in size (respectively, ~400 and ~900 km2) and age (respectively, 1.0 Ma). The San Francisco dune sheet is restricted to a short alongshore interval (km) within a relatively straight coastline (150 km in length) that borders a broad shelf (~40 km in width). The Monterey Bay dune sheet is restricted to the Monterey Bay embayment (41 km alongshore length). The embayment includes a very narrow shelf (3–15 km in width), which is dissected by the Monterey Submarine Canyon. Generally low onshore topographic relief (elevation) likely enhanced inland transgression of Late Pleistocene dune fields in both the San Francisco and Monterey Bay areas. The locations of the dune sheets are directly related to sand accumulations in marine low-stand depocenters that supplied sand to the adjacent dune fields by eolian transport across the emerged inner shelves. The San Francisco shelf depocenter is apparently localized at a midshelf bight (−50 to −100 m elevation) that extends 25 km (east–west) offshore of a paleoriver mouth of a major river system, the Sacramento–San Joaquin River. The Monterey Bay shelf depocenter is bounded alongshore by major headlands and converging paleoshorelines (−30 to −90 m elevation) that effectively trapped littoral sand from small coastal drainages, primarily the Salinas River. High vertical rates of neotectonic deformation in the San Francisco dune sheet (0.4–1.0 mm y−1) limited dune sheet longevity and deposit thickness (5–35 m). Low uplift rates (~0.1 mm y−1) in the central Monterey Bay dune sheet permitted deposit accumulations of up to 250 m thickness. The differences in dune sheet extent, thickness, and age resulted from key differences in localized shelf accommodation space and coastal neotectonic vertical movements. Close

• 49. [Article] The structural controls of the Vale Rhinehart Buttes complex, Vale KGRA, Malheur County, Oregon

  The Vale KGRA is characterized by high heat flow, two to five times higher than the worldwide average, and by numerous hot springs. The hot springs are aligned along faults. This phenomena is typical of ...

  Citation × Citation Citation Abstract Copy Title: The structural controls of the Vale Rhinehart Buttes complex, Vale KGRA, Malheur County, Oregon Author: Doerr, John Timothy Year: 1986 The Vale KGRA is characterized by high heat flow, two to five times higher than the worldwide average, and by numerous hot springs. The hot springs are aligned along faults. This phenomena is typical of a Basin and Range type geothermal system. The hot geothermal fluids migrate upward along the more permeable, fault planes. The rocks exposed in the Vale area are the Pliocene Chalk Butte formation and the Pleistocene beds of Captain Keeney Pass. Both units are composed of volcaniclastic siltstones, sandstones and conglomerates. The units are differentiated by color, texture and degree of lithification. About 200 meters of the Chalk Butte formation and 100 meters of the beds of Captain Keeney Pass are exposed in the area. Silicification is wide spread in the rocks of the Chalk Butte formation. Title: The structural controls of the Vale Rhinehart Buttes complex, Vale KGRA, Malheur County, Oregon Author: Doerr, John Timothy Year: 1986 The Vale KGRA is characterized by high heat flow, two to five times higher than the worldwide average, and by numerous hot springs. The hot springs are aligned along faults. This phenomena is typical of a Basin and Range type geothermal system. The hot geothermal fluids migrate upward along the more permeable, fault planes. The rocks exposed in the Vale area are the Pliocene Chalk Butte formation and the Pleistocene beds of Captain Keeney Pass. Both units are composed of volcaniclastic siltstones, sandstones and conglomerates. The units are differentiated by color, texture and degree of lithification. About 200 meters of the Chalk Butte formation and 100 meters of the beds of Captain Keeney Pass are exposed in the area. Silicification is wide spread in the rocks of the Chalk Butte formation. Close

• 50. [Article] A Tale of Three Sisters: Reconstructing the Holocene glacial history and paleoclimate record at Three Sisters Volcanoes, Oregon, United States

  At least four glacial stands occurred since 6.5 ka B.P. based on moraines located on the eastern flanks of the Three Sisters Volcanoes and the northern flanks of Broken Top Mountain in the Central Oregon ...

  Citation × Citation Citation Abstract Copy Title: A Tale of Three Sisters: Reconstructing the Holocene glacial history and paleoclimate record at Three Sisters Volcanoes, Oregon, United States Author: Marcott, Shaun Andrew Year: 2005 At least four glacial stands occurred since 6.5 ka B.P. based on moraines located on the eastern flanks of the Three Sisters Volcanoes and the northern flanks of Broken Top Mountain in the Central Oregon Cascades. The youngest of these advances was the Little Ice Age (LIA) glaciation, which reached its maximum advance 150-200 yrs. B.P. and is defined by the large sharp crested and unvegetated moraines adjacent to the modern glaciers. In isolated locations less than 100 m downslope from these moraines, a second set of sparsely vegetated lateral moraines marks the Late-Neoglacial stand of the glaciers between 2.1 ± 0.4 and 7.7 ka B.P, A third set of Early-Neoglacial end moraines is 300-700 meters downslope of the modern glacier termini, and postdates 7.7 ka B.P. From SST temperature data (Barron et al., 2003) and a speleothem record (Vacco, 2003), we infer that this advance occurred between 4.5 and 6.5 ka B.P. Finally, the Fountonnor stand is marked by moraines 500-900 meters downslope of the modern glacier termini, and we infer these are latest Pleistocene or early Holocene. Modem equilibrium line altitudes (ELAs) at the Three Sisters and Broken Top are approximately 2500 - 2600 m. During the LIA, the ELAs were 40 - 180 m lower, requiring cooler mean summer temperatures by 0.7 - 1.0°C and winter snowfall to increase by 10 - 60 cm water equivalent. The average Early Neoglacial and Fountonnor ELAs were 130 - 300 m and 290 - 320 m lower than modem glaciers, respectively, requiring air temperatures to be 0.7 - 1.6°C and 1.5 - 1.7°C cooler during the summer and winter snowfall to be 40 - 100 cm water equivalent and 90 - 100 cm water equivalent greater. Title: A Tale of Three Sisters: Reconstructing the Holocene glacial history and paleoclimate record at Three Sisters Volcanoes, Oregon, United States Author: Marcott, Shaun Andrew Year: 2005 At least four glacial stands occurred since 6.5 ka B.P. based on moraines located on the eastern flanks of the Three Sisters Volcanoes and the northern flanks of Broken Top Mountain in the Central Oregon Cascades. The youngest of these advances was the Little Ice Age (LIA) glaciation, which reached its maximum advance 150-200 yrs. B.P. and is defined by the large sharp crested and unvegetated moraines adjacent to the modern glaciers. In isolated locations less than 100 m downslope from these moraines, a second set of sparsely vegetated lateral moraines marks the Late-Neoglacial stand of the glaciers between 2.1 ± 0.4 and 7.7 ka B.P, A third set of Early-Neoglacial end moraines is 300-700 meters downslope of the modern glacier termini, and postdates 7.7 ka B.P. From SST temperature data (Barron et al., 2003) and a speleothem record (Vacco, 2003), we infer that this advance occurred between 4.5 and 6.5 ka B.P. Finally, the Fountonnor stand is marked by moraines 500-900 meters downslope of the modern glacier termini, and we infer these are latest Pleistocene or early Holocene. Modem equilibrium line altitudes (ELAs) at the Three Sisters and Broken Top are approximately 2500 - 2600 m. During the LIA, the ELAs were 40 - 180 m lower, requiring cooler mean summer temperatures by 0.7 - 1.0°C and winter snowfall to increase by 10 - 60 cm water equivalent. The average Early Neoglacial and Fountonnor ELAs were 130 - 300 m and 290 - 320 m lower than modem glaciers, respectively, requiring air temperatures to be 0.7 - 1.6°C and 1.5 - 1.7°C cooler during the summer and winter snowfall to be 40 - 100 cm water equivalent and 90 - 100 cm water equivalent greater. Close

• 51. [Article] Postglacial Relative Sea-Level History of the Prince Rupert Area, British Columbia, Canada

  This paper presents a history of relative sea level (RSL) change for the last 15,000 years in the Prince Rupert region on the northern coast of British Columbia, Canada. One hundred twenty-three radiocarbon ...

  Citation × Citation Citation Abstract Copy Title: Postglacial Relative Sea-Level History of the Prince Rupert Area, British Columbia, Canada Author: Letham, Bryn, Martindale, Andrew, Macdonald, Rebecca, Guiry, Eric, Jones, Jacob, Ames, Kenneth Year: 2016 This paper presents a history of relative sea level (RSL) change for the last 15,000 years in the Prince Rupert region on the northern coast of British Columbia, Canada. One hundred twenty-three radiocarbon ages of organic material from isolation basin cores, sediment sequence exposures, and archaeological sites having a recognized relation to past sea levels constrain postglacial RSL. The large number of new measurements relating to past sea-level provides a well constrained RSL curve that differs in significant ways from previously published results. After deglaciation following the Last Glacial Maximum, the region experienced an isostatically-induced rapid RSL drop from as much 50 m asl to as low as −6.3 m asl in as little as a few centuries between 14,500 BP and 13,500 BP. After a lowstand below current sea level for about 2000 years during the terminal Pleistocene, RSL rose again to a highstand at least 6 m asl after the end of the Younger Dryas. RSL slowly dropped through the Holocene to close to its current position by 2000-1500 BP, with some potential fluctuations between 3500 and 1500 BP. This study highlights variation in RSL histories across relatively short distances, which must be accounted for by local RSL reconstructions such as this one. This RSL curve aided in the identification of an 8000–9000 year old archaeological site on a 10–12 m asl terrace, which is currently the earliest dated archaeological site in the area, and it provides guidance for searching for even older archaeological remains. We highlight the utility and potential of this refined RSL history for developing surveys for other archaeological sites associated with paleoshorelines. Title: Postglacial Relative Sea-Level History of the Prince Rupert Area, British Columbia, Canada Author: Letham, Bryn, Martindale, Andrew, Macdonald, Rebecca, Guiry, Eric, Jones, Jacob, Ames, Kenneth Year: 2016 This paper presents a history of relative sea level (RSL) change for the last 15,000 years in the Prince Rupert region on the northern coast of British Columbia, Canada. One hundred twenty-three radiocarbon ages of organic material from isolation basin cores, sediment sequence exposures, and archaeological sites having a recognized relation to past sea levels constrain postglacial RSL. The large number of new measurements relating to past sea-level provides a well constrained RSL curve that differs in significant ways from previously published results. After deglaciation following the Last Glacial Maximum, the region experienced an isostatically-induced rapid RSL drop from as much 50 m asl to as low as −6.3 m asl in as little as a few centuries between 14,500 BP and 13,500 BP. After a lowstand below current sea level for about 2000 years during the terminal Pleistocene, RSL rose again to a highstand at least 6 m asl after the end of the Younger Dryas. RSL slowly dropped through the Holocene to close to its current position by 2000-1500 BP, with some potential fluctuations between 3500 and 1500 BP. This study highlights variation in RSL histories across relatively short distances, which must be accounted for by local RSL reconstructions such as this one. This RSL curve aided in the identification of an 8000–9000 year old archaeological site on a 10–12 m asl terrace, which is currently the earliest dated archaeological site in the area, and it provides guidance for searching for even older archaeological remains. We highlight the utility and potential of this refined RSL history for developing surveys for other archaeological sites associated with paleoshorelines. Close

• 52. [Article] Cultural Responses to Climate Change in the Holocene

  Variable Holocene climate conditions have caused cultures to thrive, adapt or fail. The invention of agriculture and the domestication of plants and animals allowed sedentary societies to develop and are ...

  Citation × Citation Citation Abstract Copy Title: Cultural Responses to Climate Change in the Holocene Author: Prentice, Richard Year: 2009 Variable Holocene climate conditions have caused cultures to thrive, adapt or fail. The invention of agriculture and the domestication of plants and animals allowed sedentary societies to develop and are the result of the climate becoming warmer after the last glaciation. The subsequent cooling of the Younger Dryas forced humans to concentrate into geographic areas that had an abundant water supply and ultimately favorable conditions for the use of agriculture and widespread domestication of plants and animals. Population densities would have reached a threshold and forced a return to foraging, however the end of the Younger Dryas at 10,000 BP allowed agrarian societies to grow in number and expand spatially. The Norse took advantage of the favorable climate conditions of the medieval warm period (800 to 1300 CE) to establish settlements off the coast of Greenland, but the onset of the Little Ice Age (1350-1850 CE) caused sea ice to block trade routes with China and led to their demise. The long and cold winters of the Little Ice Age inspired works of art and literature, and were celebrated in London, but also caused crop failures, famine and disease. The Dust Bowl drought of the 1930’s only lasted six years but caused the most devastating ecological, sociological, agricultural, and economic disaster in United States history. Multicentury and multidecadal droughts led to the collapse of the Akkadian, Classic Maya, Mochica, and Tiwanaku civilizations. The primary factors affecting global climate variations include changes in thermohaline circulation, solar irradiance, and the effects of active volcanoes. Complex societies are not completely powerless nor fully adaptive to climate change. Modern society should use knowledge of past abrupt climate changes to better prepare for the future. Title: Cultural Responses to Climate Change in the Holocene Author: Prentice, Richard Year: 2009 Variable Holocene climate conditions have caused cultures to thrive, adapt or fail. The invention of agriculture and the domestication of plants and animals allowed sedentary societies to develop and are the result of the climate becoming warmer after the last glaciation. The subsequent cooling of the Younger Dryas forced humans to concentrate into geographic areas that had an abundant water supply and ultimately favorable conditions for the use of agriculture and widespread domestication of plants and animals. Population densities would have reached a threshold and forced a return to foraging, however the end of the Younger Dryas at 10,000 BP allowed agrarian societies to grow in number and expand spatially. The Norse took advantage of the favorable climate conditions of the medieval warm period (800 to 1300 CE) to establish settlements off the coast of Greenland, but the onset of the Little Ice Age (1350-1850 CE) caused sea ice to block trade routes with China and led to their demise. The long and cold winters of the Little Ice Age inspired works of art and literature, and were celebrated in London, but also caused crop failures, famine and disease. The Dust Bowl drought of the 1930’s only lasted six years but caused the most devastating ecological, sociological, agricultural, and economic disaster in United States history. Multicentury and multidecadal droughts led to the collapse of the Akkadian, Classic Maya, Mochica, and Tiwanaku civilizations. The primary factors affecting global climate variations include changes in thermohaline circulation, solar irradiance, and the effects of active volcanoes. Complex societies are not completely powerless nor fully adaptive to climate change. Modern society should use knowledge of past abrupt climate changes to better prepare for the future. Close

• 53. [Article] Local Extinction and Unintentional Rewilding of Bighorn Sheep (Ovis canadensis) on a Desert Island

  To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The article was published by the Public Library ...

  Citation × Citation Citation Abstract Copy Title: Local Extinction and Unintentional Rewilding of Bighorn Sheep (Ovis canadensis) on a Desert Island Author: Betancourt, Julio L., Mead, Jim I., Epps, Clinton W., Wilder, Benjamin T., Crowhurst, Rachel S., Ezcurra, Exequiel To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The article was published by the Public Library of Science and is in the public domain. The published article can be found at: http://www.plosone.org/. Title: Local Extinction and Unintentional Rewilding of Bighorn Sheep (Ovis canadensis) on a Desert Island Author: Betancourt, Julio L., Mead, Jim I., Epps, Clinton W., Wilder, Benjamin T., Crowhurst, Rachel S., Ezcurra, Exequiel To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The article was published by the Public Library of Science and is in the public domain. The published article can be found at: http://www.plosone.org/. Close

• 54. [Article] Tectonic controls for transverse drainage and timing of the Xin-Ding paleolake breach in the upper reach of the Hutuo River, North China

  This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by Elsevier and can be found at: http://www.journals.elsevier.com/geomorphology/.

  Citation × Citation Citation Abstract Copy Title: Tectonic controls for transverse drainage and timing of the Xin-Ding paleolake breach in the upper reach of the Hutuo River, North China Author: Zhang, Shimin, Yeats, Robert S., Ren, Junjie, Meigs, Andrew J., Shen, Xiaoming, Ding, Rui This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by Elsevier and can be found at: http://www.journals.elsevier.com/geomorphology/. Title: Tectonic controls for transverse drainage and timing of the Xin-Ding paleolake breach in the upper reach of the Hutuo River, North China Author: Zhang, Shimin, Yeats, Robert S., Ren, Junjie, Meigs, Andrew J., Shen, Xiaoming, Ding, Rui This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by Elsevier and can be found at: http://www.journals.elsevier.com/geomorphology/. Close

• 55. [Article] Characterization of particulate organic matter in the Lena River delta and adjacent nearshore zone, NE Siberia – Part 2: Lignin-derived phenol compositions

  This is the publisher’s final pdf. The published article is copyrighted by the author(s) and published by Copernicus Publications on behalf of the European Geosciences Union. The published article can ...

  Citation × Citation Citation Abstract Copy Title: Characterization of particulate organic matter in the Lena River delta and adjacent nearshore zone, NE Siberia – Part 2: Lignin-derived phenol compositions Author: Hefter, J., Goñi, M. A., Mollenhauer, G., Winterfeld, M., Just, J. This is the publisher’s final pdf. The published article is copyrighted by the author(s) and published by Copernicus Publications on behalf of the European Geosciences Union. The published article can be found at: http://www.biogeosciences.net/index.html. Title: Characterization of particulate organic matter in the Lena River delta and adjacent nearshore zone, NE Siberia – Part 2: Lignin-derived phenol compositions Author: Hefter, J., Goñi, M. A., Mollenhauer, G., Winterfeld, M., Just, J. This is the publisher’s final pdf. The published article is copyrighted by the author(s) and published by Copernicus Publications on behalf of the European Geosciences Union. The published article can be found at: http://www.biogeosciences.net/index.html. Close

• 56. [Article] Organic matter compositions and loadings in soils and sediments along the Fly River, Papua New Guinea

  This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by Elsevier and can be found at: http://www.journals.elsevier.com/geochimica-et-co...

  Citation × Citation Citation Abstract Copy Title: Organic matter compositions and loadings in soils and sediments along the Fly River, Papua New Guinea Author: Merrell, David, Goni, Miguel A., Kurtz, Andrew, Alleau, Yvan, Moore, Eric, Portier, Evan This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by Elsevier and can be found at: http://www.journals.elsevier.com/geochimica-et-cosmochimica-acta/ Title: Organic matter compositions and loadings in soils and sediments along the Fly River, Papua New Guinea Author: Merrell, David, Goni, Miguel A., Kurtz, Andrew, Alleau, Yvan, Moore, Eric, Portier, Evan This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by Elsevier and can be found at: http://www.journals.elsevier.com/geochimica-et-cosmochimica-acta/ Close

• 57. [Article] Ecological Change on California’s Channel Islands from the Pleistocene to the Anthropocene

  To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The article was published by Oxford University ...

  Citation × Citation Citation Abstract Copy Title: Ecological Change on California’s Channel Islands from the Pleistocene to the Anthropocene Author: Ghalambor, Cameron K., Still, Christopher, Rick, Torben C., et al., Sillett, T. Scott To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The article was published by Oxford University Press on behalf of the American Institute of Biological Sciences and is in the public domain. The published article can be found at: http://bioscience.oxfordjournals.org/. Title: Ecological Change on California’s Channel Islands from the Pleistocene to the Anthropocene Author: Ghalambor, Cameron K., Still, Christopher, Rick, Torben C., et al., Sillett, T. Scott To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The article was published by Oxford University Press on behalf of the American Institute of Biological Sciences and is in the public domain. The published article can be found at: http://bioscience.oxfordjournals.org/. Close

• 58. [Article] Leg 202 synthesis: Southeast Pacific paleoceangraphy

  Ocean Drilling Program (ODP) Leg 202 has opened a new window into understanding late Paleogene and Neogene global environmental change by providing high-quality sediment sequences from a previously unsampled ...

  Citation × Citation Citation Abstract Copy Title: Leg 202 synthesis: Southeast Pacific paleoceangraphy Author: Tiedemann, Ralf, Mix, Alan C. Ocean Drilling Program (ODP) Leg 202 has opened a new window into understanding late Paleogene and Neogene global environmental change by providing high-quality sediment sequences from a previously unsampled region, the eastern South Pacific. Eleven sites (1232– 1242) that record variations on timescales ranging from decades to tens of millions of years were drilled and investigated on transects of both depth (489–4072 m) and latitude (41°S–8°N). Building on the shipboard results presented in the Leg 202 Initial Reports volume, postcruise research has significantly improved the stratigraphic framework and provided new insights into climate-related processes, which operate on different timescales and are relevant to hypotheses concerning the bipolar “see-saw” climate mechanism, orbitally driven changes in the continent-ocean-ice-atmosphere system and tectonic processes associated with the uplift of the Andes, closure of the Central American Seaway, and major expansions of polar ice sheets. Stable isotope records and refinements in bio- and magnetostratigraphy in combination with orbitally tuned cyclostratigraphy significantly improved the Pleistocene stratigraphy at Sites 1233 and 1234, the Miocene– Pliocene stratigraphy at Sites 1236, 1237, 1239, and 1241, and the Oligocene stratigraphy around the late Oligocene climate optimum at Site 1237. Site 1233 filled a crucial gap in the stratigraphic and paleoceanographic archive of the South Pacific sector of the Southern Ocean by providing an outstanding reproducible accelerator mass spectrometry (AMS) ¹⁴C-dated paleomagnetic record of centennial- and millennial- scale variability, representing regional variations in environmental/climatic conditions for the past 70,000 yr. With regard to the Cenozoic timetable, the continuous and complete sedimentary sequence of Site 1237, spanning the last ~31 m.y., has the potential of becoming a stratigraphic reference section for the South Pacific. Postcruise work demonstrated the excellence of this record for producing a stratigraphic framework that combines the biostratigraphy and terrific magnetostratigraphy with orbitally tuned stable isotope records. With respect to the bipolar see-saw hypotheses, Leg 202 studies on high-resolution records changed the view of the global distribution of millennial-scale climate change. These studies clearly demonstrate that millennial-scale climate and biogeochemical systems of the southeast Pacific and Chile closely align with those recorded in Antarctica and the southern oceans and that these climate patterns extend to the equatorial Pacific, either transmitted directly by the eastern boundary current or indirectly by “the oceanic tunnel” (subsurface transport via Antarctic Mode or Intermediate Water, Equatorial Undercurrent) injecting Southern Hemisphere extratropical water masses into the equatorial upwelling system. On orbital timescales, most spectacular was the finding that Earth’s final transition into an “icehouse” climate ~13.9 m.y. ago, the middle Miocene intensification of Antarctic glaciation, coincided with a striking transition from obliquity to eccentricity as the drivers of climate change. Thus, the late Pleistocene 100-k.y. climate cycles are not unique in Earth’s history, and although the examples from the Miocene and Pleistocene are both associated with climate cooling, they occur under significantly different global boundary conditions. This important contribution from Leg 202 issues a challenge to climatologists to understand multiple origins of 100-k.y. climate cycles that are now well documented in the geologic record. On timescales of millions of years, late Neogene upper ocean temperature reconstructions in combination with salinity assessments at selected sites from Leg 202 provide further insights into the reorganization of ocean-atmosphere couplings that are linked to the shoaling of the Central American Seaway (CAS), uplift of the Andes, and Pliocene amplification of polar ice sheet expansion. Regional shoaling of the thermocline in the low-latitude eastern Pacific from 5.3 to 4.0 Ma most likely resulted from shoaling of the CAS, as suggested by model experiments. Mixed-layer cooling and freshening in the tropical northeast Pacific warm pool as well as declining sea-surface temperature (SST) and increasing biological productivity off Chile parallel intensification of Northern Hemisphere glaciation from 3.6 to 2.4 Ma. The similarity of temporal changes in SST, upwelling, and dust flux between the Benguela and Chile upwelling systems suggests that uplift of the Andes was probably of secondary importance for generating the observed changes in the southeast Pacific within the last 6 m.y., as the Benguela upwelling system was not affected by mountain uplift. The expected atmosphere- oceanic response of the southeast Pacific to uplift of the Andes probably played a larger role during the late Miocene, prior to 6 Ma. A particular scientific challenge of future Leg 202 paleoclimate research is to better understand the transitions between these different timescales with respect to couplings between global, regional, and local processes. Title: Leg 202 synthesis: Southeast Pacific paleoceangraphy Author: Tiedemann, Ralf, Mix, Alan C. Ocean Drilling Program (ODP) Leg 202 has opened a new window into understanding late Paleogene and Neogene global environmental change by providing high-quality sediment sequences from a previously unsampled region, the eastern South Pacific. Eleven sites (1232– 1242) that record variations on timescales ranging from decades to tens of millions of years were drilled and investigated on transects of both depth (489–4072 m) and latitude (41°S–8°N). Building on the shipboard results presented in the Leg 202 Initial Reports volume, postcruise research has significantly improved the stratigraphic framework and provided new insights into climate-related processes, which operate on different timescales and are relevant to hypotheses concerning the bipolar “see-saw” climate mechanism, orbitally driven changes in the continent-ocean-ice-atmosphere system and tectonic processes associated with the uplift of the Andes, closure of the Central American Seaway, and major expansions of polar ice sheets. Stable isotope records and refinements in bio- and magnetostratigraphy in combination with orbitally tuned cyclostratigraphy significantly improved the Pleistocene stratigraphy at Sites 1233 and 1234, the Miocene– Pliocene stratigraphy at Sites 1236, 1237, 1239, and 1241, and the Oligocene stratigraphy around the late Oligocene climate optimum at Site 1237. Site 1233 filled a crucial gap in the stratigraphic and paleoceanographic archive of the South Pacific sector of the Southern Ocean by providing an outstanding reproducible accelerator mass spectrometry (AMS) ¹⁴C-dated paleomagnetic record of centennial- and millennial- scale variability, representing regional variations in environmental/climatic conditions for the past 70,000 yr. With regard to the Cenozoic timetable, the continuous and complete sedimentary sequence of Site 1237, spanning the last ~31 m.y., has the potential of becoming a stratigraphic reference section for the South Pacific. Postcruise work demonstrated the excellence of this record for producing a stratigraphic framework that combines the biostratigraphy and terrific magnetostratigraphy with orbitally tuned stable isotope records. With respect to the bipolar see-saw hypotheses, Leg 202 studies on high-resolution records changed the view of the global distribution of millennial-scale climate change. These studies clearly demonstrate that millennial-scale climate and biogeochemical systems of the southeast Pacific and Chile closely align with those recorded in Antarctica and the southern oceans and that these climate patterns extend to the equatorial Pacific, either transmitted directly by the eastern boundary current or indirectly by “the oceanic tunnel” (subsurface transport via Antarctic Mode or Intermediate Water, Equatorial Undercurrent) injecting Southern Hemisphere extratropical water masses into the equatorial upwelling system. On orbital timescales, most spectacular was the finding that Earth’s final transition into an “icehouse” climate ~13.9 m.y. ago, the middle Miocene intensification of Antarctic glaciation, coincided with a striking transition from obliquity to eccentricity as the drivers of climate change. Thus, the late Pleistocene 100-k.y. climate cycles are not unique in Earth’s history, and although the examples from the Miocene and Pleistocene are both associated with climate cooling, they occur under significantly different global boundary conditions. This important contribution from Leg 202 issues a challenge to climatologists to understand multiple origins of 100-k.y. climate cycles that are now well documented in the geologic record. On timescales of millions of years, late Neogene upper ocean temperature reconstructions in combination with salinity assessments at selected sites from Leg 202 provide further insights into the reorganization of ocean-atmosphere couplings that are linked to the shoaling of the Central American Seaway (CAS), uplift of the Andes, and Pliocene amplification of polar ice sheet expansion. Regional shoaling of the thermocline in the low-latitude eastern Pacific from 5.3 to 4.0 Ma most likely resulted from shoaling of the CAS, as suggested by model experiments. Mixed-layer cooling and freshening in the tropical northeast Pacific warm pool as well as declining sea-surface temperature (SST) and increasing biological productivity off Chile parallel intensification of Northern Hemisphere glaciation from 3.6 to 2.4 Ma. The similarity of temporal changes in SST, upwelling, and dust flux between the Benguela and Chile upwelling systems suggests that uplift of the Andes was probably of secondary importance for generating the observed changes in the southeast Pacific within the last 6 m.y., as the Benguela upwelling system was not affected by mountain uplift. The expected atmosphere- oceanic response of the southeast Pacific to uplift of the Andes probably played a larger role during the late Miocene, prior to 6 Ma. A particular scientific challenge of future Leg 202 paleoclimate research is to better understand the transitions between these different timescales with respect to couplings between global, regional, and local processes. Close

• 59. [Article] Paleoceanography of the Eastern Equatorial Pacific during the Neogene : synthesis of Leg 138 drilling results

  The primary objective of Leg 138 was to provide detailed information about the ocean's response to global climate change during the Neogene. Two north south transects were drilled (95° and 110°W) within ...

  Citation × Citation Citation Abstract Copy Title: Paleoceanography of the Eastern Equatorial Pacific during the Neogene : synthesis of Leg 138 drilling results Author: Mayer, Larry A., Pisias, Nicklas G., Mix, Alan C. The primary objective of Leg 138 was to provide detailed information about the ocean's response to global climate change during the Neogene. Two north south transects were drilled (95° and 110°W) within the region of equatorial divergence driven upwelling (and thus high accumulation rates and resolution) and spanning the major equatorial ocean current boundaries (and thus recording a high amplitude signal of the response of the sediment to climatically and/or tectonically driven changes in ocean circulation). The Neogene is marked by a number of well known climatic and tectonic events (the closing of the Isthmus of Panama, the onset of North Atlantic Deep Water (NADW), the rapid uplift of the Himalayas, the major intensification of Northern Hemisphere glaciation), and the response of the ocean before and after these events was a key focus of Leg 138 drilling. To address these objectives at the highest resolution possible, the Leg 138 scientific staff developed a number of new shipboard strategies and analytical procedures. These included the real time analysis of the near continuous gamma ray attenuation porosity evaluator (GRAPE) and susceptibility profiles produced by the multisensor track (MST) on unsplit cores to monitor core recovery and, if necessary, to modify the drilling strategy to ensure proper offset of coring gaps; the collection of near continuous color reflectance data on split cores; the logging of the first hole drilled at each site to optimize drilling and sampling strategies for subsequent holes; and the use of multiple continuous records to unambiguously construct complete composite sections for each site. The complete, continuous records provided by the GRAPE (with a temporal resolution of often yr), in conjunction with an excellent microfossil stratigraphy and often excellent magnetostratigraphy, allowed for astronomical tuning of the stratigraphic record and resulted in a set of internally consistent, high resolution age models that provide a secure, absolute time scale for the past 6 m.y. For the period before 6 m.y., the absolute time calibration is less secure, but it is still better than any previously offered. The high resolution stratigraphic framework of Leg 138 provided new insight into the previously ambiguous tectonic history of the region. By assuming that maximum sedimentation rates along the north south transect would be expected at the equator, the Leg 138 stratigraphy supports the 1985 work of Cox and Engerbretson, which calls for two different poles of rotation of the Pacific Plate during the interval 0-20 Ma. The Leg 138 plate reconstructions also support several previously hypothesized ridge crest jumps and a slowing of the absolute motion of the Nazca Plate at about 5 Ma. Although Leg 138 data that predates about 13 Ma is limited, the impression that one can gain from these data is that the eastern equatorial Pacific was characterized by relatively high carbonate concentrations and accumulation rates before about 11 Ma. This pattern was interrupted occasionally by rapid massive outpourings of near monospecific laminated diatom oozes that probably represent the formation of massive mats along strong surface water fronts. The laminated diatom oozes (LDO) continue to be present in the Leg 138 record (many of them being expressed as seismic reflections) until about 4.4 Ma. Carbonate accumulation rates begin to decline slowly between 11 and 9.8 Ma, when, at about 9.5 Ma, a near complete loss of carbonate (the "carbonate crash") takes place everywhere in the Leg 138 region (and beyond), except at the westernmost sites close to the equator. The "carbonate crash" was a time of fundamental change for the eastern equatorial Pacific, and perhaps for most of the ocean basins. Unlike many of the carbonate variations that precede and postdate it, this "crash" represents a major dissolution event whose effects can be traced seismically in the central and western Pacific. The changes in bottom water chemistry associated with this event (or series of events) appear to be related to the early phases of the closing of the Panama Gateway. The role of NADW initiation and intensification for controlling carbonate accumulation in the eastern equatorial Pacific is still not resolved; however, ocean modeling demonstrates that the closing of the Panama Gateway may also have a direct influence on NADW production. Therefore, the effects of changes in the Panama Gateway sill depth and the production of NADW may be manifested in the history of eastern equatorial Pacific sedimentation. The "carbonate crash" was followed by a recovery of the carbonate system (except in the Guatemala and Peru basins, which never recovered) that led up to the late Miocene/ early Pliocene sedimentation rate maxima, during which equatorial sedimentation rates are as much as five times greater than those of the late Pliocene or Pleistocene. Examination of modern productivity/ preser vation relationships implies that the sedimentation rate maximum was the result of enhanced productivity. The distribution of eolian sediments and isotopic gradients, along with an analysis of the modes of variance in carbonate deposition over the last 6 m.y., suggest a more northerly position of the Intertropical Convergence Zone (ITCZ), a stronger north south gradient across the equator, and a more zonal circulation focused along the equator during the time of maximum sedimentation. The mechanisms suggested for these changes in circulation patterns include the response of the eastern equatorial Pacific to the closing of the Isthmus of Panama, as well as a global increase in the flux of Ca and Si into the oceans, a possible response to evolution of the Himalayas and the Tibetan Plateau. In an effort to understand the response of the climate system to external (orbital) forcing, 6-m.y.-long, continuous records of carbonate (derived from GRAPE), δ¹⁸O and insolation were analyzed and compared. Evolutionary spectral calculations of the variance and coherence among these records indicate that the insolation record is dominated by precessional frequencies, but that the relative importance of the two precessional frequencies has changed significantly over the last 6 m.y. In general, precessional forcing is not found in the carbonate or isotopic records. In the tilt band, however, a linear response is present between solar forcing and the carbonate and isotope records over some intervals. The carbonate record appears to be tightly coupled to the tilt component of insolation before about 1.9 Ma; however, the isotope record does not begin to show sensitivity to orbital tilt until about 4.5 Ma, the time of significant changes in sedimentation patterns in the eastern equatorial Pacific. Only during the last 500,000 yr do all frequencies respond in a similar manner; we also see a marked increase in the response of the isotopic record to orbital forcing (including 100,000- and 400,000-yr periods). Title: Paleoceanography of the Eastern Equatorial Pacific during the Neogene : synthesis of Leg 138 drilling results Author: Mayer, Larry A., Pisias, Nicklas G., Mix, Alan C. The primary objective of Leg 138 was to provide detailed information about the ocean's response to global climate change during the Neogene. Two north south transects were drilled (95° and 110°W) within the region of equatorial divergence driven upwelling (and thus high accumulation rates and resolution) and spanning the major equatorial ocean current boundaries (and thus recording a high amplitude signal of the response of the sediment to climatically and/or tectonically driven changes in ocean circulation). The Neogene is marked by a number of well known climatic and tectonic events (the closing of the Isthmus of Panama, the onset of North Atlantic Deep Water (NADW), the rapid uplift of the Himalayas, the major intensification of Northern Hemisphere glaciation), and the response of the ocean before and after these events was a key focus of Leg 138 drilling. To address these objectives at the highest resolution possible, the Leg 138 scientific staff developed a number of new shipboard strategies and analytical procedures. These included the real time analysis of the near continuous gamma ray attenuation porosity evaluator (GRAPE) and susceptibility profiles produced by the multisensor track (MST) on unsplit cores to monitor core recovery and, if necessary, to modify the drilling strategy to ensure proper offset of coring gaps; the collection of near continuous color reflectance data on split cores; the logging of the first hole drilled at each site to optimize drilling and sampling strategies for subsequent holes; and the use of multiple continuous records to unambiguously construct complete composite sections for each site. The complete, continuous records provided by the GRAPE (with a temporal resolution of often yr), in conjunction with an excellent microfossil stratigraphy and often excellent magnetostratigraphy, allowed for astronomical tuning of the stratigraphic record and resulted in a set of internally consistent, high resolution age models that provide a secure, absolute time scale for the past 6 m.y. For the period before 6 m.y., the absolute time calibration is less secure, but it is still better than any previously offered. The high resolution stratigraphic framework of Leg 138 provided new insight into the previously ambiguous tectonic history of the region. By assuming that maximum sedimentation rates along the north south transect would be expected at the equator, the Leg 138 stratigraphy supports the 1985 work of Cox and Engerbretson, which calls for two different poles of rotation of the Pacific Plate during the interval 0-20 Ma. The Leg 138 plate reconstructions also support several previously hypothesized ridge crest jumps and a slowing of the absolute motion of the Nazca Plate at about 5 Ma. Although Leg 138 data that predates about 13 Ma is limited, the impression that one can gain from these data is that the eastern equatorial Pacific was characterized by relatively high carbonate concentrations and accumulation rates before about 11 Ma. This pattern was interrupted occasionally by rapid massive outpourings of near monospecific laminated diatom oozes that probably represent the formation of massive mats along strong surface water fronts. The laminated diatom oozes (LDO) continue to be present in the Leg 138 record (many of them being expressed as seismic reflections) until about 4.4 Ma. Carbonate accumulation rates begin to decline slowly between 11 and 9.8 Ma, when, at about 9.5 Ma, a near complete loss of carbonate (the "carbonate crash") takes place everywhere in the Leg 138 region (and beyond), except at the westernmost sites close to the equator. The "carbonate crash" was a time of fundamental change for the eastern equatorial Pacific, and perhaps for most of the ocean basins. Unlike many of the carbonate variations that precede and postdate it, this "crash" represents a major dissolution event whose effects can be traced seismically in the central and western Pacific. The changes in bottom water chemistry associated with this event (or series of events) appear to be related to the early phases of the closing of the Panama Gateway. The role of NADW initiation and intensification for controlling carbonate accumulation in the eastern equatorial Pacific is still not resolved; however, ocean modeling demonstrates that the closing of the Panama Gateway may also have a direct influence on NADW production. Therefore, the effects of changes in the Panama Gateway sill depth and the production of NADW may be manifested in the history of eastern equatorial Pacific sedimentation. The "carbonate crash" was followed by a recovery of the carbonate system (except in the Guatemala and Peru basins, which never recovered) that led up to the late Miocene/ early Pliocene sedimentation rate maxima, during which equatorial sedimentation rates are as much as five times greater than those of the late Pliocene or Pleistocene. Examination of modern productivity/ preser vation relationships implies that the sedimentation rate maximum was the result of enhanced productivity. The distribution of eolian sediments and isotopic gradients, along with an analysis of the modes of variance in carbonate deposition over the last 6 m.y., suggest a more northerly position of the Intertropical Convergence Zone (ITCZ), a stronger north south gradient across the equator, and a more zonal circulation focused along the equator during the time of maximum sedimentation. The mechanisms suggested for these changes in circulation patterns include the response of the eastern equatorial Pacific to the closing of the Isthmus of Panama, as well as a global increase in the flux of Ca and Si into the oceans, a possible response to evolution of the Himalayas and the Tibetan Plateau. In an effort to understand the response of the climate system to external (orbital) forcing, 6-m.y.-long, continuous records of carbonate (derived from GRAPE), δ¹⁸O and insolation were analyzed and compared. Evolutionary spectral calculations of the variance and coherence among these records indicate that the insolation record is dominated by precessional frequencies, but that the relative importance of the two precessional frequencies has changed significantly over the last 6 m.y. In general, precessional forcing is not found in the carbonate or isotopic records. In the tilt band, however, a linear response is present between solar forcing and the carbonate and isotope records over some intervals. The carbonate record appears to be tightly coupled to the tilt component of insolation before about 1.9 Ma; however, the isotope record does not begin to show sensitivity to orbital tilt until about 4.5 Ma, the time of significant changes in sedimentation patterns in the eastern equatorial Pacific. Only during the last 500,000 yr do all frequencies respond in a similar manner; we also see a marked increase in the response of the isotopic record to orbital forcing (including 100,000- and 400,000-yr periods). Close

• 60. [Article] Effusive silicic volcanism in the Central Andes: The Chao dacite and other young lavas of the Altiplano-Puna Volcanic Complex

  This is the publisher’s final pdf. The published article is copyrighted by the American Geophysical Union and can be found at: http://www.agu.org/journals/jgr/.

  Citation × Citation Citation Abstract Copy Title: Effusive silicic volcanism in the Central Andes: The Chao dacite and other young lavas of the Altiplano-Puna Volcanic Complex Author: Francis, P. W., Self, S., Carlos, Ramirez R., Drake, R. E., de Silva, S. L. This is the publisher’s final pdf. The published article is copyrighted by the American Geophysical Union and can be found at: http://www.agu.org/journals/jgr/. Title: Effusive silicic volcanism in the Central Andes: The Chao dacite and other young lavas of the Altiplano-Puna Volcanic Complex Author: Francis, P. W., Self, S., Carlos, Ramirez R., Drake, R. E., de Silva, S. L. This is the publisher’s final pdf. The published article is copyrighted by the American Geophysical Union and can be found at: http://www.agu.org/journals/jgr/. Close

• 61. [Article] Paleointensity of the Earth's magnetic field and K-Ar dating of the Louchadiere volcanic flow (Central France) : new evidence for the Laschamp excursion

  copyrighted by American Geophysical Union.

  Citation × Citation Citation Abstract Copy Title: Paleointensity of the Earth's magnetic field and K-Ar dating of the Louchadiere volcanic flow (Central France) : new evidence for the Laschamp excursion Author: Chauvin, Annick, Duncan, Robert A., Bonhommet, Norbert, Levi, Saul copyrighted by American Geophysical Union. Title: Paleointensity of the Earth's magnetic field and K-Ar dating of the Louchadiere volcanic flow (Central France) : new evidence for the Laschamp excursion Author: Chauvin, Annick, Duncan, Robert A., Bonhommet, Norbert, Levi, Saul copyrighted by American Geophysical Union. Close

• 62. [Article] North Atlantic Paleoceanography: The Last Five Million Years

  copyrighted by American Geophysical Union

  Citation × Citation Citation Abstract Copy Title: North Atlantic Paleoceanography: The Last Five Million Years Author: Ferretti, Partizia, Kullanek, Denise K., Zhai, Qiumin, Neilsen, Simmon H. H., Stein, Ruediger, Ohno, Masao, Rashid, Harunur, Sierro Sanchez, Francisco J., Judge, Shelley A., Bailey, Ian, Acton, Gary D., Nanayama, Futoshi, Harris, Robert N., Kanamatsu, Toshiya, Higgins, Sean M., Hefter, Jens, Alvarez-Zarikian, Carlos, Aboud, Essam, Akimoto, Kazumi, Bjorklund, Kjell R., Channell, Jim E. T., Evans, Helen, Hatakeda, Kentaro, Gruetzner, Jean, Hagino, Kentaro, Voelker, Antje copyrighted by American Geophysical Union Title: North Atlantic Paleoceanography: The Last Five Million Years Author: Ferretti, Partizia, Kullanek, Denise K., Zhai, Qiumin, Neilsen, Simmon H. H., Stein, Ruediger, Ohno, Masao, Rashid, Harunur, Sierro Sanchez, Francisco J., Judge, Shelley A., Bailey, Ian, Acton, Gary D., Nanayama, Futoshi, Harris, Robert N., Kanamatsu, Toshiya, Higgins, Sean M., Hefter, Jens, Alvarez-Zarikian, Carlos, Aboud, Essam, Akimoto, Kazumi, Bjorklund, Kjell R., Channell, Jim E. T., Evans, Helen, Hatakeda, Kentaro, Gruetzner, Jean, Hagino, Kentaro, Voelker, Antje copyrighted by American Geophysical Union Close

• 63. [Article] Seismoturbidite record as preserved at core sites at the Cascadia and Sumatra–Andaman subduction zones

  This is the publisher’s final pdf. The published article is copyrighted by Copernicus Publications and can be found at: http://publications.copernicus.org/home.html.

  Citation × Citation Citation Abstract Copy Title: Seismoturbidite record as preserved at core sites at the Cascadia and Sumatra–Andaman subduction zones Author: Patton, J. R., Udrekh, Goldfinger, C., Djadjadihardja, Y., Morey, A. E., Romsos, C., Black, B. This is the publisher’s final pdf. The published article is copyrighted by Copernicus Publications and can be found at: http://publications.copernicus.org/home.html. Title: Seismoturbidite record as preserved at core sites at the Cascadia and Sumatra–Andaman subduction zones Author: Patton, J. R., Udrekh, Goldfinger, C., Djadjadihardja, Y., Morey, A. E., Romsos, C., Black, B. This is the publisher’s final pdf. The published article is copyrighted by Copernicus Publications and can be found at: http://publications.copernicus.org/home.html. Close

• 64. [Article] Export production and carbonate dissolution in the central equatorial Pacific Ocean over the past 1 Myr

  Copyright 2000 by the American Geophysical Union

  Citation × Citation Citation Abstract Copy Title: Export production and carbonate dissolution in the central equatorial Pacific Ocean over the past 1 Myr Author: Polsky, C. H., Leinen, M., Murray, R. W., Knowlton, C. W., Mix, Alan C. Copyright 2000 by the American Geophysical Union Title: Export production and carbonate dissolution in the central equatorial Pacific Ocean over the past 1 Myr Author: Polsky, C. H., Leinen, M., Murray, R. W., Knowlton, C. W., Mix, Alan C. Copyright 2000 by the American Geophysical Union Close

• 65. [Article] Volcanoes of the Three Sisters region, Oregon Cascades

  Gerald W. Williams Collection

  Citation × Citation Citation Abstract Copy Title: Volcanoes of the Three Sisters region, Oregon Cascades Author: Williams, Howel, 1898-1980 Gerald W. Williams Collection Title: Volcanoes of the Three Sisters region, Oregon Cascades Author: Williams, Howel, 1898-1980 Gerald W. Williams Collection Close

• 66. [Article] Rapid Holocene Deglaciation of the Labrador Sector of the Laurentide Ice Sheet

  Retreat of the Laurentide Ice Sheet (LIS) following the Last Glacial Maximum 21 000 yr BP affected regional to global climate and accounted for the largest proportion of sea level rise. Although the late ...

  Citation × Citation Citation Abstract Copy Title: Rapid Holocene Deglaciation of the Labrador Sector of the Laurentide Ice Sheet Author: Brook, Edward J., Raisbeck, Grant M., Carlson, Anders E., Clark, Peter U. Retreat of the Laurentide Ice Sheet (LIS) following the Last Glacial Maximum 21 000 yr BP affected regional to global climate and accounted for the largest proportion of sea level rise. Although the late Pleistocene LIS retreat chronology is relatively well constrained, its Holocene chronology remains poorly dated, limiting our understanding of its role in Holocene climate change and sea level rise. Here new ¹⁰Be cosmogenic exposure ages on glacially deposited boulders are used to date the final disappearance of the Labrador sector of the LIS (LS-LIS). These data suggest that following the deglaciation of the southeastern Hudson Bay coastline at 8.0 ± 0.2 cal ka BP, the southwestern margin of the LS-LIS rapidly retreated ~600 km in 140 yr and most likely in ~600 yr at a rate of ~900 m yr⁻¹, with final deglaciation by 6.8 ± 0.2 ¹⁰Be ka. The disappearance of the LS-LIS ~6.8 ¹⁰Be ka and attendant reduction in freshwater runoff may have induced the formation of Labrador Deep Seawater, while the loss of the high albedo surface may have initiated the Holocene Thermal Maximum in eastern Canada and southern Greenland. Moreover, the rapid melting just prior to ~6.8 ¹⁰Be ka indicates that the remnant LIS may be the primary source of a postulated rapid rise in global sea level of ~5 m that occurred sometime between 7.6 and 6.5 cal ka BP. Title: Rapid Holocene Deglaciation of the Labrador Sector of the Laurentide Ice Sheet Author: Brook, Edward J., Raisbeck, Grant M., Carlson, Anders E., Clark, Peter U. Retreat of the Laurentide Ice Sheet (LIS) following the Last Glacial Maximum 21 000 yr BP affected regional to global climate and accounted for the largest proportion of sea level rise. Although the late Pleistocene LIS retreat chronology is relatively well constrained, its Holocene chronology remains poorly dated, limiting our understanding of its role in Holocene climate change and sea level rise. Here new ¹⁰Be cosmogenic exposure ages on glacially deposited boulders are used to date the final disappearance of the Labrador sector of the LIS (LS-LIS). These data suggest that following the deglaciation of the southeastern Hudson Bay coastline at 8.0 ± 0.2 cal ka BP, the southwestern margin of the LS-LIS rapidly retreated ~600 km in 140 yr and most likely in ~600 yr at a rate of ~900 m yr⁻¹, with final deglaciation by 6.8 ± 0.2 ¹⁰Be ka. The disappearance of the LS-LIS ~6.8 ¹⁰Be ka and attendant reduction in freshwater runoff may have induced the formation of Labrador Deep Seawater, while the loss of the high albedo surface may have initiated the Holocene Thermal Maximum in eastern Canada and southern Greenland. Moreover, the rapid melting just prior to ~6.8 ¹⁰Be ka indicates that the remnant LIS may be the primary source of a postulated rapid rise in global sea level of ~5 m that occurred sometime between 7.6 and 6.5 cal ka BP. Close

• 67. [Article] Virola dominicana sp. nov., (Myristicaceae) from Dominican amber

  This is an author's manuscript version. The published article is copyrighted by NRC Research Press and can be found at: http://www.nrcresearchpress.com/doi/full/10.1139/cjb-2013-0019.

  Citation × Citation Citation Abstract Copy Title: Virola dominicana sp. nov., (Myristicaceae) from Dominican amber Author: Poinar, George, Jr., Steeves, Royce This is an author's manuscript version. The published article is copyrighted by NRC Research Press and can be found at: http://www.nrcresearchpress.com/doi/full/10.1139/cjb-2013-0019. Title: Virola dominicana sp. nov., (Myristicaceae) from Dominican amber Author: Poinar, George, Jr., Steeves, Royce This is an author's manuscript version. The published article is copyrighted by NRC Research Press and can be found at: http://www.nrcresearchpress.com/doi/full/10.1139/cjb-2013-0019. Close

• 68. [Article] Biogenic and terrigenous sedimetations at Ceara rise, western tropical Altantic, supports Pliocene - Pleistocene deep - water linkage between hemispheres

  Calcium carbonate percentages at five Ceara Rise sites were estimated at 1- to 2-k.y. intervals over the past 5 m.y., using reflectance spectroscopy and magnetic susceptibility proxies. From these estimates ...

  Citation × Citation Citation Abstract Copy Title: Biogenic and terrigenous sedimetations at Ceara rise, western tropical Altantic, supports Pliocene - Pleistocene deep - water linkage between hemispheres Author: Harris, Sara E., King, Terri, Mix, Alan C. Calcium carbonate percentages at five Ceara Rise sites were estimated at 1- to 2-k.y. intervals over the past 5 m.y., using reflectance spectroscopy and magnetic susceptibility proxies. From these estimates and detailed correlations between sites, gradients of calcite and terrigenous sediment accumulation rates in a depth transect of sites reveal variations in local climate and calcite dissolution related to deep-water masses. Relative to shallow sites on the southern Ceara Rise, accumulation rates of terrigenous sediments at deeper sites near the Amazon Fan were higher during glacial periods. Analogous variations in terrigenous sedimentation before the expansion of Northern Hemisphere ice sheets ~3 m.y. ago suggests that tropical climate cycles occurred independently of polar glaciation. Decreasing accumulation rates of calcite with increasing water depth reveal patterns of carbonate dissolution, which varied on orbital time-scales (10- 100 k.y. periods) throughout the Pliocene-Pleistocene. Maximum dissolution at deep relative to shallow sites occurred in the transition from interglacial to glacial conditions, and maximum preservation occurred during global warming, at all orbital periods. If the local dissolution gradient is linked to relative contributions of North Atlantic Deep Water and Antarctic Bottom Water, this phasing of events confirms a key prediction of SPECMAP that deep-water adjustments may translate climate changes between hemispheres. Dissolution and preservation events, however, may also reflect a transient response to a net flux of organic matter between the continents and the oceans during ice-age climate transitions. Title: Biogenic and terrigenous sedimetations at Ceara rise, western tropical Altantic, supports Pliocene - Pleistocene deep - water linkage between hemispheres Author: Harris, Sara E., King, Terri, Mix, Alan C. Calcium carbonate percentages at five Ceara Rise sites were estimated at 1- to 2-k.y. intervals over the past 5 m.y., using reflectance spectroscopy and magnetic susceptibility proxies. From these estimates and detailed correlations between sites, gradients of calcite and terrigenous sediment accumulation rates in a depth transect of sites reveal variations in local climate and calcite dissolution related to deep-water masses. Relative to shallow sites on the southern Ceara Rise, accumulation rates of terrigenous sediments at deeper sites near the Amazon Fan were higher during glacial periods. Analogous variations in terrigenous sedimentation before the expansion of Northern Hemisphere ice sheets ~3 m.y. ago suggests that tropical climate cycles occurred independently of polar glaciation. Decreasing accumulation rates of calcite with increasing water depth reveal patterns of carbonate dissolution, which varied on orbital time-scales (10- 100 k.y. periods) throughout the Pliocene-Pleistocene. Maximum dissolution at deep relative to shallow sites occurred in the transition from interglacial to glacial conditions, and maximum preservation occurred during global warming, at all orbital periods. If the local dissolution gradient is linked to relative contributions of North Atlantic Deep Water and Antarctic Bottom Water, this phasing of events confirms a key prediction of SPECMAP that deep-water adjustments may translate climate changes between hemispheres. Dissolution and preservation events, however, may also reflect a transient response to a net flux of organic matter between the continents and the oceans during ice-age climate transitions. Close

• 69. [Article] Oblique strike-slip faulting of the central Cascadia submarine forearc

  Copyrighted by American Geophysical Union.

  Citation × Citation Citation Abstract Copy Title: Oblique strike-slip faulting of the central Cascadia submarine forearc Author: Yeats, Robert S., Goldfinger, Chris, Hummon, Cheryl, McNeill, Lisa, Kulm, LaVerne D. Copyrighted by American Geophysical Union. Title: Oblique strike-slip faulting of the central Cascadia submarine forearc Author: Yeats, Robert S., Goldfinger, Chris, Hummon, Cheryl, McNeill, Lisa, Kulm, LaVerne D. Copyrighted by American Geophysical Union. Close

• 70. [Article] Garwood Valley, Antarctica: A new record of Last Glacial Maximum to Holocene glaciofluvial processes in the McMurdo Dry Valleys

  To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by the Geological ...

  Citation × Citation Citation Abstract Copy Title: Garwood Valley, Antarctica: A new record of Last Glacial Maximum to Holocene glaciofluvial processes in the McMurdo Dry Valleys Author: Fountain, Andrew G., Welch, Kathy A., Lyons, W. Berry, O'Connor, Jim E., Levy, Joseph S. To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by the Geological Society of America and can be found at: http://gsabulletin.gsapubs.org/. Title: Garwood Valley, Antarctica: A new record of Last Glacial Maximum to Holocene glaciofluvial processes in the McMurdo Dry Valleys Author: Fountain, Andrew G., Welch, Kathy A., Lyons, W. Berry, O'Connor, Jim E., Levy, Joseph S. To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by the Geological Society of America and can be found at: http://gsabulletin.gsapubs.org/. Close

• 71. [Article] Stream channel stability and sensitivity to landscape history and land use changes in Kelley Creek, Portland, Oregon

  This study examines stream channel erosion processes in a small urbanizing watershed influenced by deposits of the Columbia Basin catastrophic floods: Kelley Creek, a 12-km² tributary of Johnson Creek, ...

  Citation × Citation Citation Abstract Copy Title: Stream channel stability and sensitivity to landscape history and land use changes in Kelley Creek, Portland, Oregon Author: Murphy, Yarrow M. This study examines stream channel erosion processes in a small urbanizing watershed influenced by deposits of the Columbia Basin catastrophic floods: Kelley Creek, a 12-km² tributary of Johnson Creek, located just east of Portland, Oregon. Information on landscape history, stream channels, and sediment dynamics was compiled. The effects of future land use changes on stream channel response were projected. The likely effects of engineered solutions (stormwater management detention or infiltration facilities) are compared to land-use controls in mitigating the impact of future development on channel erosion. The geology of Kelley Creek is shaped by volcanic processes and Missoula floods, leading to fine-textured soils and streambeds that are susceptible to erosion. Headwaters are buttes of the Boring Lava formation overlain by Springwater Formation mudflow deposits. Alluvial silts deposited during late Pleistocene catastrophic floods mantle the low-relief valley floor. Land use in Kelley Creek transitioned from forestry to agriculture in the 20th century, and more recently to urban expansion, increasing concerns of watershed managers about effects of development on sediment dynamics. Since 1930, land use on the valley floor of Kelley Creek has been dominated by nursery and berry agricultural production. Forested headwaters have been impacted by roads, culverts, and timber harvest. Seven percent of watershed area is currently impervious, with housing and commercial uses projected to increase following the incorporation of Kelley Creek into Portland's metropolitan urban growth boundary. Field surveys and engineering calculations were used to estimate sediment transport under current and future conditions in the watershed. Cross sectional geometry, slope and sediment size distributions were obtained from 15 locations in first to second-order channels in the watershed, and data were analyzed with sediment transport equations to simulate annual sediment transport rates given current and post-development flow patterns. Results indicate that the stream channel is most sensitive to altered discharge patterns where gravel-sized (D₅₀ > 10 mm) sediments currently are mobilized during annual peak events. In locations where fine (D₅₀ < 5 mm) particles dominate the stream bed, particles mobilize throughout the year and changes in discharge patterns do not increase the duration of transport or overall bedload yields. Because most of the sensitive locations with gravel sediments are located within or near the forested headwaters, preserving these headwater forests will protect sensitive stream channels as effectively as engineered stormwater retention or infiltration approaches. Kelley Creek's stream channel is still adjusting to recent mudflows and catastrophic floods, which provided abundant supplies of fine, erodible materials. Allowing this adjustment to continue without accelerating erosion in the face of rapid urban development poses an unusual challenge for managing geomorphic processes. Title: Stream channel stability and sensitivity to landscape history and land use changes in Kelley Creek, Portland, Oregon Author: Murphy, Yarrow M. This study examines stream channel erosion processes in a small urbanizing watershed influenced by deposits of the Columbia Basin catastrophic floods: Kelley Creek, a 12-km² tributary of Johnson Creek, located just east of Portland, Oregon. Information on landscape history, stream channels, and sediment dynamics was compiled. The effects of future land use changes on stream channel response were projected. The likely effects of engineered solutions (stormwater management detention or infiltration facilities) are compared to land-use controls in mitigating the impact of future development on channel erosion. The geology of Kelley Creek is shaped by volcanic processes and Missoula floods, leading to fine-textured soils and streambeds that are susceptible to erosion. Headwaters are buttes of the Boring Lava formation overlain by Springwater Formation mudflow deposits. Alluvial silts deposited during late Pleistocene catastrophic floods mantle the low-relief valley floor. Land use in Kelley Creek transitioned from forestry to agriculture in the 20th century, and more recently to urban expansion, increasing concerns of watershed managers about effects of development on sediment dynamics. Since 1930, land use on the valley floor of Kelley Creek has been dominated by nursery and berry agricultural production. Forested headwaters have been impacted by roads, culverts, and timber harvest. Seven percent of watershed area is currently impervious, with housing and commercial uses projected to increase following the incorporation of Kelley Creek into Portland's metropolitan urban growth boundary. Field surveys and engineering calculations were used to estimate sediment transport under current and future conditions in the watershed. Cross sectional geometry, slope and sediment size distributions were obtained from 15 locations in first to second-order channels in the watershed, and data were analyzed with sediment transport equations to simulate annual sediment transport rates given current and post-development flow patterns. Results indicate that the stream channel is most sensitive to altered discharge patterns where gravel-sized (D₅₀ > 10 mm) sediments currently are mobilized during annual peak events. In locations where fine (D₅₀ < 5 mm) particles dominate the stream bed, particles mobilize throughout the year and changes in discharge patterns do not increase the duration of transport or overall bedload yields. Because most of the sensitive locations with gravel sediments are located within or near the forested headwaters, preserving these headwater forests will protect sensitive stream channels as effectively as engineered stormwater retention or infiltration approaches. Kelley Creek's stream channel is still adjusting to recent mudflows and catastrophic floods, which provided abundant supplies of fine, erodible materials. Allowing this adjustment to continue without accelerating erosion in the face of rapid urban development poses an unusual challenge for managing geomorphic processes. Close

• 72. [Article] Processes of sea-cliff erosion on the Oregon coast : from neotectonics to wave run-up

  Sea-cliff erosion is a significant problem along the Oregon coast in that many communities have been built on terraces affected by bluff retreat. There is considerable coast-wide variability in the rates ...

  Citation × Citation Citation Abstract Copy Title: Processes of sea-cliff erosion on the Oregon coast : from neotectonics to wave run-up Author: Shih, Shyuer-ming Sea-cliff erosion is a significant problem along the Oregon coast in that many communities have been built on terraces affected by bluff retreat. There is considerable coast-wide variability in the rates of cliff erosion. This variability is attributed in part to tectonic activity that is causing differential interseismic uplift along the coast. Analyses of geodetic survey data and tide gauge measurements have established rates of local sea-level rise along the entire coast, including areas lacking direct tide measurements. A littoral cell around the Lincoln City area on the central Oregon Coast is experiencing the smallest degree of tectonic uplift and this results in the highest rate of local sea-level rise and significant sea-cliff erosion. High cliffs cut into a Pleistocene marine terrace, consisting of semi-consolidated sands, back the beaches over the length of the littoral cell and supply coarse-grained sands to the beaches in the south of the cell. Dissections of multimodal grain-size distributions of the beach and cliff sands have shown that coarse-fraction modes are resistant to longshore wave dispersion, and this produces a marked longshore variation in the coarseness of beach sand, in the beach morphology, and in the nearshore processes affecting the cliff-toe erosion. Two years of monthly beach-profile surveys at eleven beaches along the Lincoln City littoral cell have shown that there is a significant difference in volumetric changes between beaches of different sand sizes. The coarse-grained reflective beaches are much more dynamic in profile changes, and the total quantity of sand moved under a given storm is much greater than on the fine-grained dissipative beaches. Rip-current embayments are also more important to cliff erosion o the reflective beach, producing bluff retreat that has a high degree of spatial variability and is extremely episodic. Risk assessments based on the probability curve of the extreme run-up have demonstrated that the height of the cliff-beach junction and the beach slope are important factors in controlling the risk of cliff-toe erosion. Run-up measurements using video techniques on three beaches having contrasting morphologies suggest that the maximum run-up calculation based on the empirical relationship derived by Holman and Sallenger (1985) appears to be valid, although the permeability effects might have contributed to a significance deviation in the prediction of maximum run-up on a sediment-starved beach. Title: Processes of sea-cliff erosion on the Oregon coast : from neotectonics to wave run-up Author: Shih, Shyuer-ming Sea-cliff erosion is a significant problem along the Oregon coast in that many communities have been built on terraces affected by bluff retreat. There is considerable coast-wide variability in the rates of cliff erosion. This variability is attributed in part to tectonic activity that is causing differential interseismic uplift along the coast. Analyses of geodetic survey data and tide gauge measurements have established rates of local sea-level rise along the entire coast, including areas lacking direct tide measurements. A littoral cell around the Lincoln City area on the central Oregon Coast is experiencing the smallest degree of tectonic uplift and this results in the highest rate of local sea-level rise and significant sea-cliff erosion. High cliffs cut into a Pleistocene marine terrace, consisting of semi-consolidated sands, back the beaches over the length of the littoral cell and supply coarse-grained sands to the beaches in the south of the cell. Dissections of multimodal grain-size distributions of the beach and cliff sands have shown that coarse-fraction modes are resistant to longshore wave dispersion, and this produces a marked longshore variation in the coarseness of beach sand, in the beach morphology, and in the nearshore processes affecting the cliff-toe erosion. Two years of monthly beach-profile surveys at eleven beaches along the Lincoln City littoral cell have shown that there is a significant difference in volumetric changes between beaches of different sand sizes. The coarse-grained reflective beaches are much more dynamic in profile changes, and the total quantity of sand moved under a given storm is much greater than on the fine-grained dissipative beaches. Rip-current embayments are also more important to cliff erosion o the reflective beach, producing bluff retreat that has a high degree of spatial variability and is extremely episodic. Risk assessments based on the probability curve of the extreme run-up have demonstrated that the height of the cliff-beach junction and the beach slope are important factors in controlling the risk of cliff-toe erosion. Run-up measurements using video techniques on three beaches having contrasting morphologies suggest that the maximum run-up calculation based on the empirical relationship derived by Holman and Sallenger (1985) appears to be valid, although the permeability effects might have contributed to a significance deviation in the prediction of maximum run-up on a sediment-starved beach. Close

• 73. [Article] Sedimentary texture--a key to interpret deep-marine dynamics

  The processes responsible for transporting and depositing thick sections of coarse-grained terrigenous clastics on the abyssal floor and for forming associated sedimentary structures are still conjectural. Many ...

  Citation × Citation Citation Abstract Copy Title: Sedimentary texture--a key to interpret deep-marine dynamics Author: Allen, David William The processes responsible for transporting and depositing thick sections of coarse-grained terrigenous clastics on the abyssal floor and for forming associated sedimentary structures are still conjectural. Many workers attribute coarse deep-sea sediments and their probable lithified equivalent, the graywackes of flysch deposits to some type of density movement. Deductions concerning the processes operating in a density flow generally are made from flume studies--in which an artificial situation may develop, or from lithified units--where the magnitude of post-depositional change is unknown. Both approaches contribute to our knowledge, but the unconsolidated elastics themselves should contain a unique key to understanding the dynamics of abyssal sedimentation. To test this theory, divisions of parallel lamination, found in deep-sea sand and silt, were selected for analysis. Since individual laminae closely approach discrete populations of particles assembled under contrasting conditions, their use carries environmental sampling to its practical limits. Northeast Pacific sediments of late Pleistocene and Holocene age, from deep-sea channel and abyssal plain environments, and representing two or three provenances were studied. A total of 115 light-colored and 84 dark-colored laminae were sampled from eight sequences at five locations. Samples averaged about 0.8 gram and were quantitatively processed using quarter-phi calibrated sieves and decantation techniques. Statistical evaluation of the procedure shows better than 95 percent sample recovery, and indicates that textural variance between laminae is significantly greater than within-sample variance. The classic concept of density transport--that coarsest material is carried by the nose of the current, and that clastic size grades tail-ward and upward in a uniformly decreasing manner--is not substantiated by moment measures, sand-silt-clay percentages or factor analysis of grain-size distributions, at least during deposition of the coarse division of parallel lamination. Coarse abyssal lamination develops within a narrow range of current velocity, the limits of which are defined texturally. Absolute velocity values for these limits can only be related, at the present time, to the few flume or in situ bottom current measurements available. Texture indicates that while the total amount of sand carried in suspension varies, lamination does not begin to form until a current is essentially depleted of all material coarser than fine sand--establishing an upper competency limit. At that time, coarse suspended material is distributed throughout the flow mostly in large eddies or vortices whose velocities are estimated on the order of about one meter/sec. Mean current velocity must be sufficient to maintain a dispersed traction carpet without deformation of bedform into ripples. This is postulated at about 50 cm/sec. A current model, based on textural evidence, is proposed to account for lamination. It is suggested that the critical stage in the formation of coarse abyssal lamination occurs while sediment is being dragged along the bottom as bedload. The flowing clastic traction carpet acquires kinetic energy as the current bypasses material lost from suspension. In turn, this energy results in grain shear. When the concentration of granular material in traction is large, it dissipates the energy of bottom shear mostly in collision contacts between gliding grains. The dispersive stresses developed tend to maintain grain separation and prevent settling. Eventually, turbulence in seawater entrapped between grains is suppressed and the net path of grans impelled by repeated collisions becomes quasi-laminar. Within this quasi-laminar traction system, dispersive pressure causes some migration of finer sizes toward the base of the carpet and a concentration of coarser grains in the upper bedload. As new material is introduced in large quantities from suspension, the zone of internal shear--the base of the moving carpet--is displaced progressively upward. As it passes, sediment compacts to a fraction of its dispersed thickness and a population of grains with a slightly finer size distribution than the carpet load comes to rest. This is buried by new deposition and a densely-packed, dark layer continues to accrete upward as long as a moving traction carpet is sustained and a dense rain of clastics is contributed from suspension. When a sand-laden eddy impinges on the bottom, it releases its coarsest load into traction and the dark layer then accreting increases significantly in grains larger than 44 microns. Any eddy, whether laden or not, on striking bottom adds to, or deducts its velocity from the velocity of the traction carpet and either increases or decreases bottom shear. Additional impulse given to tractive shear by eddies merely results in more effective size sorting. However, an eddy whose velocity of rotation is opposed to current movement may reduce shear below the critical necessary to maintain a thick carpet by dispersive pressure, The dispersed carpet collapses and instantaneously ceases moving. This less-densely packed layer has a slightly higher sand content than the accreted material below. When partially dried or weathered, alternate layers exhibit different moisture retention properties--the less-porous, accreted layers appearing dark and the more loosely packed layers appearing light. Title: Sedimentary texture--a key to interpret deep-marine dynamics Author: Allen, David William The processes responsible for transporting and depositing thick sections of coarse-grained terrigenous clastics on the abyssal floor and for forming associated sedimentary structures are still conjectural. Many workers attribute coarse deep-sea sediments and their probable lithified equivalent, the graywackes of flysch deposits to some type of density movement. Deductions concerning the processes operating in a density flow generally are made from flume studies--in which an artificial situation may develop, or from lithified units--where the magnitude of post-depositional change is unknown. Both approaches contribute to our knowledge, but the unconsolidated elastics themselves should contain a unique key to understanding the dynamics of abyssal sedimentation. To test this theory, divisions of parallel lamination, found in deep-sea sand and silt, were selected for analysis. Since individual laminae closely approach discrete populations of particles assembled under contrasting conditions, their use carries environmental sampling to its practical limits. Northeast Pacific sediments of late Pleistocene and Holocene age, from deep-sea channel and abyssal plain environments, and representing two or three provenances were studied. A total of 115 light-colored and 84 dark-colored laminae were sampled from eight sequences at five locations. Samples averaged about 0.8 gram and were quantitatively processed using quarter-phi calibrated sieves and decantation techniques. Statistical evaluation of the procedure shows better than 95 percent sample recovery, and indicates that textural variance between laminae is significantly greater than within-sample variance. The classic concept of density transport--that coarsest material is carried by the nose of the current, and that clastic size grades tail-ward and upward in a uniformly decreasing manner--is not substantiated by moment measures, sand-silt-clay percentages or factor analysis of grain-size distributions, at least during deposition of the coarse division of parallel lamination. Coarse abyssal lamination develops within a narrow range of current velocity, the limits of which are defined texturally. Absolute velocity values for these limits can only be related, at the present time, to the few flume or in situ bottom current measurements available. Texture indicates that while the total amount of sand carried in suspension varies, lamination does not begin to form until a current is essentially depleted of all material coarser than fine sand--establishing an upper competency limit. At that time, coarse suspended material is distributed throughout the flow mostly in large eddies or vortices whose velocities are estimated on the order of about one meter/sec. Mean current velocity must be sufficient to maintain a dispersed traction carpet without deformation of bedform into ripples. This is postulated at about 50 cm/sec. A current model, based on textural evidence, is proposed to account for lamination. It is suggested that the critical stage in the formation of coarse abyssal lamination occurs while sediment is being dragged along the bottom as bedload. The flowing clastic traction carpet acquires kinetic energy as the current bypasses material lost from suspension. In turn, this energy results in grain shear. When the concentration of granular material in traction is large, it dissipates the energy of bottom shear mostly in collision contacts between gliding grains. The dispersive stresses developed tend to maintain grain separation and prevent settling. Eventually, turbulence in seawater entrapped between grains is suppressed and the net path of grans impelled by repeated collisions becomes quasi-laminar. Within this quasi-laminar traction system, dispersive pressure causes some migration of finer sizes toward the base of the carpet and a concentration of coarser grains in the upper bedload. As new material is introduced in large quantities from suspension, the zone of internal shear--the base of the moving carpet--is displaced progressively upward. As it passes, sediment compacts to a fraction of its dispersed thickness and a population of grains with a slightly finer size distribution than the carpet load comes to rest. This is buried by new deposition and a densely-packed, dark layer continues to accrete upward as long as a moving traction carpet is sustained and a dense rain of clastics is contributed from suspension. When a sand-laden eddy impinges on the bottom, it releases its coarsest load into traction and the dark layer then accreting increases significantly in grains larger than 44 microns. Any eddy, whether laden or not, on striking bottom adds to, or deducts its velocity from the velocity of the traction carpet and either increases or decreases bottom shear. Additional impulse given to tractive shear by eddies merely results in more effective size sorting. However, an eddy whose velocity of rotation is opposed to current movement may reduce shear below the critical necessary to maintain a thick carpet by dispersive pressure, The dispersed carpet collapses and instantaneously ceases moving. This less-densely packed layer has a slightly higher sand content than the accreted material below. When partially dried or weathered, alternate layers exhibit different moisture retention properties--the less-porous, accreted layers appearing dark and the more loosely packed layers appearing light. 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• 74. [Article] Paleomagnetic inclination shallowing in deep-sea sediments

  In this thesis anomalous downcore shallowing of paleomagnetic inclinations is interpreted to be caused by sediment compaction. Thus, compaction-induced inclination shallowing may influence tectonic reconstructions ...

  Citation × Citation Citation Abstract Copy Title: Paleomagnetic inclination shallowing in deep-sea sediments Author: Arason, Pórdur In this thesis anomalous downcore shallowing of paleomagnetic inclinations is interpreted to be caused by sediment compaction. Thus, compaction-induced inclination shallowing may influence tectonic reconstructions that are based on inclinations from deep-sea sediment cores. Progressive downcore shallowing of the remanent inclination was observed in a 120-m section of Plio- Pleistocene sediments at Deep Sea Drilling Project (DSDP) site 578 in the northwest Pacific. Near the top of the section the average inclination corresponds to the expected geocentric axial dipole value of 53° but shallows downcore by about 6° to 8°. In sediments spanning the same time interval of neighboring site 576, no inclination shallowing was observed. This second site has considerably lower sedimentation rates, and the Plio- Pleistocene is represented by a 26-m sedimentary section. The inclination shallowing at site 578 was correlated to a downhole decrease in porosity, and these results are interpreted to suggest that both the downhole inclination shallowing and decrease of porosity in site 578 were caused by sediment compaction. Microscopic models demonstrate that sediment compaction may lead to inclination shallowing of the magnetic remanence. Furthermore, it is shown that inherent initial within-sample dispersion of the magnetic moments will transform any form of microscopic mechanism to an equation of a standardized form: tan (I-ΔI) = (1-a ΔV) tan I, where I is the inclination of the ambient field, ΔI is the inclination shallowing, a is a constant and ΔV the compaction. Paleomagnetic inclinations of Cretaceous DSDP sediments from the Pacific plate are known to be systematically shallower than predicted from paleolatitudes of hot spot reconstructions. Published paleomagnetic data were reexamined and the shallow Cretaceous inclinations explained as a result of sediment compaction. The Cretaceous data are used to estimate the parameter a. The resulting a values are comparable to those of previous studies of compaction-induced inclination shallowing, both from laboratory experiments and the considerably younger deep-sea sediments at site 578. Values of the parameter a suggest that it might be controlled by sediment lithology with greater shallowing for clayey than calcareous sediments. Title: Paleomagnetic inclination shallowing in deep-sea sediments Author: Arason, Pórdur In this thesis anomalous downcore shallowing of paleomagnetic inclinations is interpreted to be caused by sediment compaction. Thus, compaction-induced inclination shallowing may influence tectonic reconstructions that are based on inclinations from deep-sea sediment cores. Progressive downcore shallowing of the remanent inclination was observed in a 120-m section of Plio- Pleistocene sediments at Deep Sea Drilling Project (DSDP) site 578 in the northwest Pacific. Near the top of the section the average inclination corresponds to the expected geocentric axial dipole value of 53° but shallows downcore by about 6° to 8°. In sediments spanning the same time interval of neighboring site 576, no inclination shallowing was observed. This second site has considerably lower sedimentation rates, and the Plio- Pleistocene is represented by a 26-m sedimentary section. The inclination shallowing at site 578 was correlated to a downhole decrease in porosity, and these results are interpreted to suggest that both the downhole inclination shallowing and decrease of porosity in site 578 were caused by sediment compaction. Microscopic models demonstrate that sediment compaction may lead to inclination shallowing of the magnetic remanence. Furthermore, it is shown that inherent initial within-sample dispersion of the magnetic moments will transform any form of microscopic mechanism to an equation of a standardized form: tan (I-ΔI) = (1-a ΔV) tan I, where I is the inclination of the ambient field, ΔI is the inclination shallowing, a is a constant and ΔV the compaction. Paleomagnetic inclinations of Cretaceous DSDP sediments from the Pacific plate are known to be systematically shallower than predicted from paleolatitudes of hot spot reconstructions. Published paleomagnetic data were reexamined and the shallow Cretaceous inclinations explained as a result of sediment compaction. The Cretaceous data are used to estimate the parameter a. The resulting a values are comparable to those of previous studies of compaction-induced inclination shallowing, both from laboratory experiments and the considerably younger deep-sea sediments at site 578. Values of the parameter a suggest that it might be controlled by sediment lithology with greater shallowing for clayey than calcareous sediments. Close

• 75. [Article] Clay mineral origin and distribution on Astoria Fan

  Clay minerals from sediment samples obtained on Astoria Fan were analyzed by X-ray diffraction. Clay minerals are defined for the purpose of this study as crystalline phyllosilicates less than two microns ...

  Citation × Citation Citation Abstract Copy Title: Clay mineral origin and distribution on Astoria Fan Author: Russell, Kenneth Lloyd Clay minerals from sediment samples obtained on Astoria Fan were analyzed by X-ray diffraction. Clay minerals are defined for the purpose of this study as crystalline phyllosilicates less than two microns in equivalent settling diameter. The clay minerals are subdivided into the five common families: montmorillonite, chlorite, vermiculite, illite, and kaolinite. One X-ray scan of a magnesium ion saturated, ethylene glycol treated sample was sufficient for the identification of all the clay minerals. A typical Recent hemipelagic sediment contains about 40 percent montmorillonite, 30 percent illite, and 30 percent chlorite. Neither kaolinite nor vermiculite is detectable in these samples. These concentrations are similar to those reported for Columbia River sediments. The surface sediments have an identical clay mineral assemblage from the head of Astoria Canyon to the outer edge of the fan approximately 250 kilometers offshore. All of the Recent sediments in piston cores from Astoria Fan are the same as the surface sediments on the fan. This similarity indicates an unchanging source during Recent time and a lack of any visible marine diagenesis after burial. X-ray traces of Pleistocene clay minerals are distinctly different from those of the Recent. One can use this change in clay mineralogy as a time marker across the fan. Presumably the Pleistocene clays were formed under different weathering conditions caused by different climatic conditions. Title: Clay mineral origin and distribution on Astoria Fan Author: Russell, Kenneth Lloyd Clay minerals from sediment samples obtained on Astoria Fan were analyzed by X-ray diffraction. Clay minerals are defined for the purpose of this study as crystalline phyllosilicates less than two microns in equivalent settling diameter. The clay minerals are subdivided into the five common families: montmorillonite, chlorite, vermiculite, illite, and kaolinite. One X-ray scan of a magnesium ion saturated, ethylene glycol treated sample was sufficient for the identification of all the clay minerals. A typical Recent hemipelagic sediment contains about 40 percent montmorillonite, 30 percent illite, and 30 percent chlorite. Neither kaolinite nor vermiculite is detectable in these samples. These concentrations are similar to those reported for Columbia River sediments. The surface sediments have an identical clay mineral assemblage from the head of Astoria Canyon to the outer edge of the fan approximately 250 kilometers offshore. All of the Recent sediments in piston cores from Astoria Fan are the same as the surface sediments on the fan. This similarity indicates an unchanging source during Recent time and a lack of any visible marine diagenesis after burial. X-ray traces of Pleistocene clay minerals are distinctly different from those of the Recent. One can use this change in clay mineralogy as a time marker across the fan. Presumably the Pleistocene clays were formed under different weathering conditions caused by different climatic conditions. Close

• 76. [Article] Late Pleistocene lithic technological organization on the southern Oregon coast : investigations at Indian Sands (35-CU-67C)

  Excavations conducted at Indian Sands (35-CU-67C), located along Oregon's southern coast, during 2002 and 2003 identified two discreet, artifact-bearing stratigraphic units. The uppermost unit is a deflated ...

  Citation × Citation Citation Abstract Copy Title: Late Pleistocene lithic technological organization on the southern Oregon coast : investigations at Indian Sands (35-CU-67C) Author: Willis, Samuel C. Excavations conducted at Indian Sands (35-CU-67C), located along Oregon's southern coast, during 2002 and 2003 identified two discreet, artifact-bearing stratigraphic units. The uppermost unit is a deflated surface containing burnt shell and lithic artifacts associated with early Holocene ¹⁴C dates, while the underlying unit contained only lithic tools and debitage, some of which were associated with a ¹⁴C date of 10,430 ± 150 RCYBP. The late Pleistocene lithic assemblage at 35-CU-67C provides the earliest evidence for human presence on the Oregon coast to date. Analysis performed on the late Pleistocene assemblage addresses the validity of existing hypotheses regarding the nature of early Oregon coastal hunter-gatherer technological and subsistence strategies. These hypotheses are focused on whether early populations on the Oregon coast practiced a generalist-forager or collector subsistence strategy. Using theoretical approaches that deal with the organization of hunter-gatherer technology, analyses were conducted on the lithic tool and debitage assemblages at 35-CU- 67C in order to infer past hunter-gatherer behavior. Through the implementation of multiple tool and debitage analysis methodologies, issues of hunter-gatherer mobility, raw material procurement, stages of lithic reduction, tool production, and site function are presented. The data generated by the late Pleistocene lithic assemblage at 35-CU-67C are compared with the overlying surficial assemblage, additional early sites along the North American Pacific coast, and to contemporaneous sites located further inland within the Pacific Northwest region. Results of the lithic analyses at 35-CU-67C show distinct similarities in debitage trends between the assemblages of each stratigraphic unit. However, when tool assemblages from these units are compared, discrepancies in the types and amount of tools are found. Reasons for intra-site variability and similarity are explained through raw material studies and site function at 35-CU-67C. Additionally, similarities between the early tool assemblage at 35-CU-67C and those found in early tool assemblages on the extended Pacific coast and interior Pacific Northwest regions are discussed. This thesis demonstrates that early southern Oregon coastal populations had a tendency towards high mobility and used a generalized toolkit organization. Early lithic technology used at 35-CU-67C emphasized multidirectional core technology and biface manufacture in the form of preforms and leaf-shaped projectile-points. This type of technological organization is to be expected from hunter-gatherers practicing a generalist-forager subsistence strategy. Based on the 10,430 ± 150 RCYBP date and technological organization at 35-CU-67C, early Oregon coastal occupation is seen as encompassing a generalist-forager subsistence strategy most likely adapted to both coastal and terrestrial environments. Title: Late Pleistocene lithic technological organization on the southern Oregon coast : investigations at Indian Sands (35-CU-67C) Author: Willis, Samuel C. Excavations conducted at Indian Sands (35-CU-67C), located along Oregon's southern coast, during 2002 and 2003 identified two discreet, artifact-bearing stratigraphic units. The uppermost unit is a deflated surface containing burnt shell and lithic artifacts associated with early Holocene ¹⁴C dates, while the underlying unit contained only lithic tools and debitage, some of which were associated with a ¹⁴C date of 10,430 ± 150 RCYBP. The late Pleistocene lithic assemblage at 35-CU-67C provides the earliest evidence for human presence on the Oregon coast to date. Analysis performed on the late Pleistocene assemblage addresses the validity of existing hypotheses regarding the nature of early Oregon coastal hunter-gatherer technological and subsistence strategies. These hypotheses are focused on whether early populations on the Oregon coast practiced a generalist-forager or collector subsistence strategy. Using theoretical approaches that deal with the organization of hunter-gatherer technology, analyses were conducted on the lithic tool and debitage assemblages at 35-CU- 67C in order to infer past hunter-gatherer behavior. Through the implementation of multiple tool and debitage analysis methodologies, issues of hunter-gatherer mobility, raw material procurement, stages of lithic reduction, tool production, and site function are presented. The data generated by the late Pleistocene lithic assemblage at 35-CU-67C are compared with the overlying surficial assemblage, additional early sites along the North American Pacific coast, and to contemporaneous sites located further inland within the Pacific Northwest region. Results of the lithic analyses at 35-CU-67C show distinct similarities in debitage trends between the assemblages of each stratigraphic unit. However, when tool assemblages from these units are compared, discrepancies in the types and amount of tools are found. Reasons for intra-site variability and similarity are explained through raw material studies and site function at 35-CU-67C. Additionally, similarities between the early tool assemblage at 35-CU-67C and those found in early tool assemblages on the extended Pacific coast and interior Pacific Northwest regions are discussed. This thesis demonstrates that early southern Oregon coastal populations had a tendency towards high mobility and used a generalized toolkit organization. Early lithic technology used at 35-CU-67C emphasized multidirectional core technology and biface manufacture in the form of preforms and leaf-shaped projectile-points. This type of technological organization is to be expected from hunter-gatherers practicing a generalist-forager subsistence strategy. Based on the 10,430 ± 150 RCYBP date and technological organization at 35-CU-67C, early Oregon coastal occupation is seen as encompassing a generalist-forager subsistence strategy most likely adapted to both coastal and terrestrial environments. Close

• 77. [Article] Millennial-scale surface and deep water oscillations in the N.E. Pacific : implications for late pleistocene climate change

  Citation × Citation Citation Abstract Copy Title: Millennial-scale surface and deep water oscillations in the N.E. Pacific : implications for late pleistocene climate change Author: Lund, David Charles Title: Millennial-scale surface and deep water oscillations in the N.E. Pacific : implications for late pleistocene climate change Author: Lund, David Charles Close

• 78. [Article] Model of late Pleistocene-Holocene variations in rate of sediment accumulation : Panama Basin, eastern equatorial Pacific

  The assumption of constant quartz accumulation for the deep-sea sediment core Y69-106P, taken in the Panama Basin, has been used to date the core and construct a sedimentation rate versus time curve for ...

  Citation × Citation Citation Abstract Copy Title: Model of late Pleistocene-Holocene variations in rate of sediment accumulation : Panama Basin, eastern equatorial Pacific Author: Pisias, Nicklas G. The assumption of constant quartz accumulation for the deep-sea sediment core Y69-106P, taken in the Panama Basin, has been used to date the core and construct a sedimentation rate versus time curve for it. Stratigraphic control for the calculated time scale includes three carbon-14 measurements, the extinction of the radiolarian Stylatractus universus, and correlation with oxygen isotope curves from other dated cores. The model sedimentation rates and sediment composition data allow the determination of sediment accumulation rates for calcium carbonate, opaline silica, and remaining "detritus". Fluctuations in calcium carbonate accumulation rates correlate closely with variations in oxygen isotope ratios in biogenous carbonate from two other equatorial Pacific sediment cores. High oxygen isotope ratios correlate with high calcium carbonate accumulation rates. Opaline silica accumulation rates reflect changes in the dominance of radiolarian fossil groups which can be related to surface circulation in the Panama Basin. The successive maxima in opal and calcium accumulation rates and the oxygen isotope ratios in Y69-106P suggest that at the end of the last glacial period, the rate of calcium carbonate dissolution increased in the Panama Basin first, to be followed by a decrease in the intensity of the eastern equatorial Pacific upwelling, and finally the volume of continental glaciers decreased. Spectral analysis of the rate of accumulation of calcium carbonate in Y69-106P and of the oxygen isotope record of core V28-238 indicate the presence of a 23,000 year periodicity. Analysis of opal accumulation rate suggest a 100,000 year periodicity. These two periodicities are found in fluctuations in the earth's orbital parameters. The eccentricity of the orbit fluctuates with an average period of 98,000 years and the precession of the equinoxes changes with a 22,000 year period. Title: Model of late Pleistocene-Holocene variations in rate of sediment accumulation : Panama Basin, eastern equatorial Pacific Author: Pisias, Nicklas G. The assumption of constant quartz accumulation for the deep-sea sediment core Y69-106P, taken in the Panama Basin, has been used to date the core and construct a sedimentation rate versus time curve for it. Stratigraphic control for the calculated time scale includes three carbon-14 measurements, the extinction of the radiolarian Stylatractus universus, and correlation with oxygen isotope curves from other dated cores. The model sedimentation rates and sediment composition data allow the determination of sediment accumulation rates for calcium carbonate, opaline silica, and remaining "detritus". Fluctuations in calcium carbonate accumulation rates correlate closely with variations in oxygen isotope ratios in biogenous carbonate from two other equatorial Pacific sediment cores. High oxygen isotope ratios correlate with high calcium carbonate accumulation rates. Opaline silica accumulation rates reflect changes in the dominance of radiolarian fossil groups which can be related to surface circulation in the Panama Basin. The successive maxima in opal and calcium accumulation rates and the oxygen isotope ratios in Y69-106P suggest that at the end of the last glacial period, the rate of calcium carbonate dissolution increased in the Panama Basin first, to be followed by a decrease in the intensity of the eastern equatorial Pacific upwelling, and finally the volume of continental glaciers decreased. Spectral analysis of the rate of accumulation of calcium carbonate in Y69-106P and of the oxygen isotope record of core V28-238 indicate the presence of a 23,000 year periodicity. Analysis of opal accumulation rate suggest a 100,000 year periodicity. These two periodicities are found in fluctuations in the earth's orbital parameters. The eccentricity of the orbit fluctuates with an average period of 98,000 years and the precession of the equinoxes changes with a 22,000 year period. Close

• 79. [Article] Origin and distribution of the fish fauna of the Harney Basin, Oregon

  A theory of the origin and distribution of fishes in the Harney Basin is presented. Blitzen River, the hydrographically and ecologically isolated creeks, and the upland tributaries of Silvies River all ...

  Citation × Citation Citation Abstract Copy Title: Origin and distribution of the fish fauna of the Harney Basin, Oregon Author: Bisson, Peter Andre A theory of the origin and distribution of fishes in the Harney Basin is presented. Blitzen River, the hydrographically and ecologically isolated creeks, and the upland tributaries of Silvies River all contain populations derived from the basin's Pleistocene connection with Malheur River of the Snake system. Colonization of many streams took Place during periods of high precipitation; isolation has resulted froth dessicating trends since the last glaciation. Stream capture has apparently facilitated a secondary invasion of fishes into Silvies River from John Day River, a tributary of the lower Columbia. This conclusion is further supported by the presence of several species only in central Silvies River within the basin. Certain populations similar to those occurring in isolated regions of the Harney Basin also exist above the barrier falls of the south fork of John Day River, but this drainage is believed to be another disrupted fragment containing descendants of a more ancient Columbia fauna. Speculation regarding the sequence of radiation of different species throughout the Columbia watershed is aided by distributional patterns and knowledge of hydrographic history. Title: Origin and distribution of the fish fauna of the Harney Basin, Oregon Author: Bisson, Peter Andre A theory of the origin and distribution of fishes in the Harney Basin is presented. Blitzen River, the hydrographically and ecologically isolated creeks, and the upland tributaries of Silvies River all contain populations derived from the basin's Pleistocene connection with Malheur River of the Snake system. Colonization of many streams took Place during periods of high precipitation; isolation has resulted froth dessicating trends since the last glaciation. Stream capture has apparently facilitated a secondary invasion of fishes into Silvies River from John Day River, a tributary of the lower Columbia. This conclusion is further supported by the presence of several species only in central Silvies River within the basin. Certain populations similar to those occurring in isolated regions of the Harney Basin also exist above the barrier falls of the south fork of John Day River, but this drainage is believed to be another disrupted fragment containing descendants of a more ancient Columbia fauna. Speculation regarding the sequence of radiation of different species throughout the Columbia watershed is aided by distributional patterns and knowledge of hydrographic history. Close

• 80. [Article] The fruits and seeds of the Rancho La Brea Pleistocene deposits

  More than 4,000 specimens of fruits and seeds were extracted from the matrix removed from inside the skulls of sabre-tooth cats excavated from various pits in the Rancho La Brea deposits. Of this number, ...

  Citation × Citation Citation Abstract Copy Title: The fruits and seeds of the Rancho La Brea Pleistocene deposits Author: Templeton, Bonnie Carolyn More than 4,000 specimens of fruits and seeds were extracted from the matrix removed from inside the skulls of sabre-tooth cats excavated from various pits in the Rancho La Brea deposits. Of this number, spproximately 1,445 specimens are involved in this study. Many comparisons with modern fruits and seeds made it possible to make identification of this material. There are 15 families comprising 20 genera and 30 species recorded in this report of the Rancho La Brea Pleistocene flora. Of this number, four species and four varieties are new to the Pleistocene floras. Eleven of the 30 species occur in the flora of the area today, eleven now occur in areas so remote from the Rancho La Brea site that they could not have been carried by flood waters into the areas of deposition, and therefore, must have been living near to the asphalt beds in order that entrapment could occur. Eight of the species are now extinct. Based on the requirements of their modern counterparts, ecologically, many of the species live in riparian situations or more moist locations than prevail today in the area of deposition. The average rainfall for the range of a number of the modern representatives of the fossils was correlated. From these data it appears that the climate may have been cooler and more moist during the period of deposition, and the species occurring in southern California at that time would have required 2- to 25 inches for their continued existence. It may be assumed that when this average dropped below 20 inches for long periods of time, the species either receded to areas with suitable rainfall or became extinct. Title: The fruits and seeds of the Rancho La Brea Pleistocene deposits Author: Templeton, Bonnie Carolyn More than 4,000 specimens of fruits and seeds were extracted from the matrix removed from inside the skulls of sabre-tooth cats excavated from various pits in the Rancho La Brea deposits. Of this number, spproximately 1,445 specimens are involved in this study. Many comparisons with modern fruits and seeds made it possible to make identification of this material. There are 15 families comprising 20 genera and 30 species recorded in this report of the Rancho La Brea Pleistocene flora. Of this number, four species and four varieties are new to the Pleistocene floras. Eleven of the 30 species occur in the flora of the area today, eleven now occur in areas so remote from the Rancho La Brea site that they could not have been carried by flood waters into the areas of deposition, and therefore, must have been living near to the asphalt beds in order that entrapment could occur. Eight of the species are now extinct. Based on the requirements of their modern counterparts, ecologically, many of the species live in riparian situations or more moist locations than prevail today in the area of deposition. The average rainfall for the range of a number of the modern representatives of the fossils was correlated. From these data it appears that the climate may have been cooler and more moist during the period of deposition, and the species occurring in southern California at that time would have required 2- to 25 inches for their continued existence. It may be assumed that when this average dropped below 20 inches for long periods of time, the species either receded to areas with suitable rainfall or became extinct. Close

• 81. [Article] Paleoenvironmental reconstruction of an active margin coast from the Pleistocene to the present : examples from southwestern Oregon

  This study illustrates geoarchaeological and paleoenvironmental approaches to the investigation of an active margin coastal setting and provides examples of how information gleaned through examination ...

  Citation × Citation Citation Abstract Copy Title: Paleoenvironmental reconstruction of an active margin coast from the Pleistocene to the present : examples from southwestern Oregon Author: Punke, Michele Leigh This study illustrates geoarchaeological and paleoenvironmental approaches to the investigation of an active margin coastal setting and provides examples of how information gleaned through examination of the stratigraphic record can reveal depositional signatures that provide insights into the geomorphic and tectonic forces active within coastal river basins. Three case studies from the southern Oregon coast illustrate the complex relationship between tectonics and geomorphic processes along an active margin coast such as Oregon's Cascadia subduction zone. This work illustrates that the differential preservation of late Pleistocene-age terrestrial deposits in Oregon's coastal landscape, and the early cultural sites they may contain, is not random but can be closely related to larger tectonogeomorphic processes operating at local and regional scales. Detailed subsurface investigation of one case study site, the lower Sixes River valley, reveals a complex history of depositional environment evolution in relation to geomorphic and tectonic forces. Litho- and biostratigraphic data sets are used to develop a depositional environment reconstruction for the lower Sixes River site through time. This reconstruction of the depositional environment from the late Pleistocene to the present indicates a transgressive evolution that differs from models of transgressive coastal facies and from other studied Northwest coast estuarine life histories. Factors such as eustatic sea level rise, regional and local tectonic alteration of the landscape, sediment supply, or valley morphology may have played roles in the creation and preservation of this atypical depositional sequence. Litho- and biostratigraphic evidence of six Cascadia subduction zone earthquakes younger than 6200 cal yr BP is recorded in a long sediment core from the Sixes River valley. All six of these events correlate with events previously reported for the area by Kelsey et al. (2002). At least five additional plate boundary earthquakes lowered tidal marshes and freshwater wetlands prior to 6200 cal yr BP. The presence within the lower Sixes River valley of an intertidal environment capable of recording Cascadia subduction zone earthquakes dating to the late Pleistocene and early Holocene has not been found at any other location on the Northwest coast. Title: Paleoenvironmental reconstruction of an active margin coast from the Pleistocene to the present : examples from southwestern Oregon Author: Punke, Michele Leigh This study illustrates geoarchaeological and paleoenvironmental approaches to the investigation of an active margin coastal setting and provides examples of how information gleaned through examination of the stratigraphic record can reveal depositional signatures that provide insights into the geomorphic and tectonic forces active within coastal river basins. Three case studies from the southern Oregon coast illustrate the complex relationship between tectonics and geomorphic processes along an active margin coast such as Oregon's Cascadia subduction zone. This work illustrates that the differential preservation of late Pleistocene-age terrestrial deposits in Oregon's coastal landscape, and the early cultural sites they may contain, is not random but can be closely related to larger tectonogeomorphic processes operating at local and regional scales. Detailed subsurface investigation of one case study site, the lower Sixes River valley, reveals a complex history of depositional environment evolution in relation to geomorphic and tectonic forces. Litho- and biostratigraphic data sets are used to develop a depositional environment reconstruction for the lower Sixes River site through time. This reconstruction of the depositional environment from the late Pleistocene to the present indicates a transgressive evolution that differs from models of transgressive coastal facies and from other studied Northwest coast estuarine life histories. Factors such as eustatic sea level rise, regional and local tectonic alteration of the landscape, sediment supply, or valley morphology may have played roles in the creation and preservation of this atypical depositional sequence. Litho- and biostratigraphic evidence of six Cascadia subduction zone earthquakes younger than 6200 cal yr BP is recorded in a long sediment core from the Sixes River valley. All six of these events correlate with events previously reported for the area by Kelsey et al. (2002). At least five additional plate boundary earthquakes lowered tidal marshes and freshwater wetlands prior to 6200 cal yr BP. The presence within the lower Sixes River valley of an intertidal environment capable of recording Cascadia subduction zone earthquakes dating to the late Pleistocene and early Holocene has not been found at any other location on the Northwest coast. Close

• 82. [Article] Constraints of the origin of the middle Pleistocene transition from the glacial sedimentary record of the north-central United States

  This dissertation focuses on the role of ice sheets in the transition during the middle Pleistocene (-1.2 Ma) from 41-kyr glacial cycles to 100-kyr glacial cycles. This research evaluates the hypothesis ...

  Citation × Citation Citation Abstract Copy Title: Constraints of the origin of the middle Pleistocene transition from the glacial sedimentary record of the north-central United States Author: Roy, Martin This dissertation focuses on the role of ice sheets in the transition during the middle Pleistocene (-1.2 Ma) from 41-kyr glacial cycles to 100-kyr glacial cycles. This research evaluates the hypothesis that the middle Pleistocene transition (MPT) was related to the glacial erosion of a regolith mantle and the subsequent exposure of fresh crystalline bedrock. This issue is addressed through the study of glacial sedimentary sequences in Iowa, Nebraska, Kansas, and Missouri. Testing the hypothesis first required the establishment of a stratigraphic framework for pre-Illinoian glacial sequences. A chronology developed around till compositional data and chronological constraints provided by paleomagnetic measurements on glacigenic sediments, and three volcanic ashes, indicate that the midcontinent tills can be grouped under three categories representing at least seven ice advances: two older groups of reverse-polarity tills containing a low and intermediate proportion of clasts and minerals derived from crystalline bedrock, respectively, and one younger group of normal-polarity tills enriched in crystalline materials. The bulk geochemistry of the silicate fraction of the midcontinent tills was then used to evaluate the character of the rock source eroded by ice sheets. The results show a general trend in which geochemical indices, from oldest to youngest tills, fall parallel to a mixing line defined by the composition of a weathered and fresh crystalline rock sources, respectively. The content in meteoric 10Be of tills also supports the existence of a regolith and its glacial erosion by -1.3 Ma, thus concordant with the onset of the MPT. Marine records of strontium, hafnium, and osmium isotopes provide additional support for the hypothesis. The nature of the till compositional changes was further addressed through a provenance study based on 504 40Ar/39Ar ages measured on individual K-feldspar grains retrieved from tills that span the last 2 Myr. Most samples yielded ages identical to those of numerical ages of the Churchill Province, thereby constraining deposition by ice from the western (Keewatin) sector of the Laurentide ice sheet. These results rule out a change in provenance, and thus show support for a change in the composition of the Churchill bedrock source during the late Cenozoic. Title: Constraints of the origin of the middle Pleistocene transition from the glacial sedimentary record of the north-central United States Author: Roy, Martin This dissertation focuses on the role of ice sheets in the transition during the middle Pleistocene (-1.2 Ma) from 41-kyr glacial cycles to 100-kyr glacial cycles. This research evaluates the hypothesis that the middle Pleistocene transition (MPT) was related to the glacial erosion of a regolith mantle and the subsequent exposure of fresh crystalline bedrock. This issue is addressed through the study of glacial sedimentary sequences in Iowa, Nebraska, Kansas, and Missouri. Testing the hypothesis first required the establishment of a stratigraphic framework for pre-Illinoian glacial sequences. A chronology developed around till compositional data and chronological constraints provided by paleomagnetic measurements on glacigenic sediments, and three volcanic ashes, indicate that the midcontinent tills can be grouped under three categories representing at least seven ice advances: two older groups of reverse-polarity tills containing a low and intermediate proportion of clasts and minerals derived from crystalline bedrock, respectively, and one younger group of normal-polarity tills enriched in crystalline materials. The bulk geochemistry of the silicate fraction of the midcontinent tills was then used to evaluate the character of the rock source eroded by ice sheets. The results show a general trend in which geochemical indices, from oldest to youngest tills, fall parallel to a mixing line defined by the composition of a weathered and fresh crystalline rock sources, respectively. The content in meteoric 10Be of tills also supports the existence of a regolith and its glacial erosion by -1.3 Ma, thus concordant with the onset of the MPT. Marine records of strontium, hafnium, and osmium isotopes provide additional support for the hypothesis. The nature of the till compositional changes was further addressed through a provenance study based on 504 40Ar/39Ar ages measured on individual K-feldspar grains retrieved from tills that span the last 2 Myr. Most samples yielded ages identical to those of numerical ages of the Churchill Province, thereby constraining deposition by ice from the western (Keewatin) sector of the Laurentide ice sheet. These results rule out a change in provenance, and thus show support for a change in the composition of the Churchill bedrock source during the late Cenozoic. Close

• 83. [Article] The case for NE-SW extension in northeast Oregon

  A zone of diffuse deformation -600 km-wide extending from northern California to Washington has developed resulting from the oblique subduction of the Juan de Fuca plate beneath North America, and the ...

  Citation × Citation Citation Abstract Copy Title: The case for NE-SW extension in northeast Oregon Author: Essman, Jim E. A zone of diffuse deformation -600 km-wide extending from northern California to Washington has developed resulting from the oblique subduction of the Juan de Fuca plate beneath North America, and the northwestward migration of the Pacific plate. This zone is marked by a change in structural style from transtension in the southern Oregon and western Nevada to transpression in southern and western Washington. The transition occurs across a relatively inactive zone in northeastern Oregon. New geologic mapping near the northern edge of this transitional zone suggests that extensional deformation persists into northeastern Oregon. The study area on the Oregon-Idaho border, is a complex zone characterized by NNWtrending primarily sinistral-oblique normal faults linking the NW-trending Halfway and Sturgill Peak (both down to the NE) normal faults to the NW and SE, respectively. The Halfway fault, -20 km-long - 730 m dip-slip separation, marks the southern boundary of a half-graben; whereas the Sturgill Peak fault, - 10 to 15 km long and not associated with a half-graben, has a minimum dip-slip separation of - 660 m. In contrast, the transfer zone informally named the Powder River Peninsula Fault Zone, or PRPFZ, houses numerous -NNW-striking, 2 to 3 km-long normal and sinistral-oblique normal faults with dip-slip separations of < 130 m. Evidence of late Pleistocene-Holocene deformation within the transfer zone is found in at least four places, and at two of those involves sinistral-oblique normal faults (-10-15 m vertical separation on a bedrock scarp) cutting late Pleistocene Bonneville flood gravels, -14 ka, with flood gravels both entrained in the fault plane and interbedded with Holocene colluvium implying significant activity in the late Pleistocene and possibly the early Holocene. Additionally, one fault in the PRPFZ cuts Holocene (?) soils/clays and deforms Pleistocene ash beds. Slip rates calculated from slickenlines and separations in the PRPFZ range from 0.01 mm/yr to possibly as high as 2.8 mm/yr to. This detailed slip data for the PRPFZ can be used as a proxy for the more regional deformational styles. Although the Halfway and Sturgill Peak faults have been interpreted to represent the southeastern extension of the Olympic-Wallowa Lineament (OWL), the tectonic and structural significance of the OWL remains poorly understood. It is suggested here that these structures reflect the continuation of Basinand-Range style deformation into northeastern Oregon, and western Idaho, and any connection to the OWL to be circumstantial. Furthermore, the presence of these structures poses a potential seismic hazard to local hydroelectric facilities. Title: The case for NE-SW extension in northeast Oregon Author: Essman, Jim E. A zone of diffuse deformation -600 km-wide extending from northern California to Washington has developed resulting from the oblique subduction of the Juan de Fuca plate beneath North America, and the northwestward migration of the Pacific plate. This zone is marked by a change in structural style from transtension in the southern Oregon and western Nevada to transpression in southern and western Washington. The transition occurs across a relatively inactive zone in northeastern Oregon. New geologic mapping near the northern edge of this transitional zone suggests that extensional deformation persists into northeastern Oregon. The study area on the Oregon-Idaho border, is a complex zone characterized by NNWtrending primarily sinistral-oblique normal faults linking the NW-trending Halfway and Sturgill Peak (both down to the NE) normal faults to the NW and SE, respectively. The Halfway fault, -20 km-long - 730 m dip-slip separation, marks the southern boundary of a half-graben; whereas the Sturgill Peak fault, - 10 to 15 km long and not associated with a half-graben, has a minimum dip-slip separation of - 660 m. In contrast, the transfer zone informally named the Powder River Peninsula Fault Zone, or PRPFZ, houses numerous -NNW-striking, 2 to 3 km-long normal and sinistral-oblique normal faults with dip-slip separations of < 130 m. Evidence of late Pleistocene-Holocene deformation within the transfer zone is found in at least four places, and at two of those involves sinistral-oblique normal faults (-10-15 m vertical separation on a bedrock scarp) cutting late Pleistocene Bonneville flood gravels, -14 ka, with flood gravels both entrained in the fault plane and interbedded with Holocene colluvium implying significant activity in the late Pleistocene and possibly the early Holocene. Additionally, one fault in the PRPFZ cuts Holocene (?) soils/clays and deforms Pleistocene ash beds. Slip rates calculated from slickenlines and separations in the PRPFZ range from 0.01 mm/yr to possibly as high as 2.8 mm/yr to. This detailed slip data for the PRPFZ can be used as a proxy for the more regional deformational styles. Although the Halfway and Sturgill Peak faults have been interpreted to represent the southeastern extension of the Olympic-Wallowa Lineament (OWL), the tectonic and structural significance of the OWL remains poorly understood. It is suggested here that these structures reflect the continuation of Basinand-Range style deformation into northeastern Oregon, and western Idaho, and any connection to the OWL to be circumstantial. Furthermore, the presence of these structures poses a potential seismic hazard to local hydroelectric facilities. Close

• 84. [Article] Snow Peak, OR: late Miocene to early Pliocene volcanism in the central Cascadia forearc

  Snow Peak is a voluminous shield volcano located ~50 km west of the axis of the modern Cascade arc. A previously published K-Ar age estimate indicates that the Snow Peak lavas are ~3 Ma. Subsequently, ...

  Citation × Citation Citation Abstract Copy Title: Snow Peak, OR: late Miocene to early Pliocene volcanism in the central Cascadia forearc Author: Hatfield, Ashley K. Snow Peak is a voluminous shield volcano located ~50 km west of the axis of the modern Cascade arc. A previously published K-Ar age estimate indicates that the Snow Peak lavas are ~3 Ma. Subsequently, the preliminary research framework for studying the Snow Peak lavas focused on constraining the petrogenesis of the primitive lava compositions, thereby addressing the chemical and thermal structure of the Cascadia forearc mantle. However, ⁴⁰Ar/³⁹Ar age dating conducted for this study indicates that the Snow Peak lavas are ~5.5 – 6 Ma. Consequently, the research framework undertaken for this thesis focused on constraining the petrogenetic pathway of the Snow Peak lavas, thereby addressing the volcano-tectonic development of the early High Cascades. ⁴⁰Ar/³⁹Ar age results for the spatial range of the Snow Peak volcanic center indicate that the volcano formed between ~5.5 and 6 Ma. Whole-rock major and trace element geochemical results indicate that Snow Peak is a monogenetic, basaltic volcanic center that unconformably overlies the Western Cascades. Petrographic analysis coupled with end-member mineral chemistry results indicate that phenocryst phases consist of olivine, pyroxene, and plagioclase. Decompression crystal fractionation of this phase assemblage explains the observed liquid line of descent. Phase equilibria modeling in COMAGMAT of a selected primitive, and a selected daughter sample, indicate that differentiation of the Snow Peak lavas began ~8-10 kb, and ~1150°C – 1200°C, and the Snow Peak daughter formed ~1-2 kb and ~1050°C – 1150°C. A plagioclase hygrometer indicates that the Snow Peak lavas contain ~2 wt % H₂O. These results are consistent with melting of moderately enriched mantle and addition of a relatively small amount of LILE-enriched slab-derived material. The timing of volcanism at Snow Peak correlates to the development of an intra-arc rift, marked by the eruption of voluminous mafic lava flows, such as the Deschutes Formation, and early Mt. Jefferson basalts. Mafic underplating may have played a greater role in Cascadia volcanism during such periods of intra-arc rifting, and such an extensional tectonic setting could facilitate the eruption of basaltic lavas. Additionally, Snow Peak aligns with the NW-trending Brother's Fault zone, although the Snow Peak center lies on the western side of the arc axis. Snow Peak magma may have formed in response to decompression associated with uplift along the Brother's Fault zone, with a fluid flux from the downgoing slab. Title: Snow Peak, OR: late Miocene to early Pliocene volcanism in the central Cascadia forearc Author: Hatfield, Ashley K. Snow Peak is a voluminous shield volcano located ~50 km west of the axis of the modern Cascade arc. A previously published K-Ar age estimate indicates that the Snow Peak lavas are ~3 Ma. Subsequently, the preliminary research framework for studying the Snow Peak lavas focused on constraining the petrogenesis of the primitive lava compositions, thereby addressing the chemical and thermal structure of the Cascadia forearc mantle. However, ⁴⁰Ar/³⁹Ar age dating conducted for this study indicates that the Snow Peak lavas are ~5.5 – 6 Ma. Consequently, the research framework undertaken for this thesis focused on constraining the petrogenetic pathway of the Snow Peak lavas, thereby addressing the volcano-tectonic development of the early High Cascades. ⁴⁰Ar/³⁹Ar age results for the spatial range of the Snow Peak volcanic center indicate that the volcano formed between ~5.5 and 6 Ma. Whole-rock major and trace element geochemical results indicate that Snow Peak is a monogenetic, basaltic volcanic center that unconformably overlies the Western Cascades. Petrographic analysis coupled with end-member mineral chemistry results indicate that phenocryst phases consist of olivine, pyroxene, and plagioclase. Decompression crystal fractionation of this phase assemblage explains the observed liquid line of descent. Phase equilibria modeling in COMAGMAT of a selected primitive, and a selected daughter sample, indicate that differentiation of the Snow Peak lavas began ~8-10 kb, and ~1150°C – 1200°C, and the Snow Peak daughter formed ~1-2 kb and ~1050°C – 1150°C. A plagioclase hygrometer indicates that the Snow Peak lavas contain ~2 wt % H₂O. These results are consistent with melting of moderately enriched mantle and addition of a relatively small amount of LILE-enriched slab-derived material. The timing of volcanism at Snow Peak correlates to the development of an intra-arc rift, marked by the eruption of voluminous mafic lava flows, such as the Deschutes Formation, and early Mt. Jefferson basalts. Mafic underplating may have played a greater role in Cascadia volcanism during such periods of intra-arc rifting, and such an extensional tectonic setting could facilitate the eruption of basaltic lavas. Additionally, Snow Peak aligns with the NW-trending Brother's Fault zone, although the Snow Peak center lies on the western side of the arc axis. Snow Peak magma may have formed in response to decompression associated with uplift along the Brother's Fault zone, with a fluid flux from the downgoing slab. Close

• 85. [Article] Alpine glacier and pluvial lake records of late pleistocene climate variability in the western United States

  Citation × Citation Citation Abstract Copy Title: Alpine glacier and pluvial lake records of late pleistocene climate variability in the western United States Author: Licciardi, Joseph M. Title: Alpine glacier and pluvial lake records of late pleistocene climate variability in the western United States Author: Licciardi, Joseph M. Close

• 86. [Article] Genetic diversity in coastal cutthroat trout and Dolly Varden in Prince William Sound, Alaska

  Genetic diversity of two salmonid species, Dolly Varden (Salvelinus malma) and coastal cutthroat trout (Oncorhynchus clarki clarki) in Prince William Sound, Alaska were examined at multiple spatial scales ...

  Citation × Citation Citation Abstract Copy Title: Genetic diversity in coastal cutthroat trout and Dolly Varden in Prince William Sound, Alaska Author: Griswold, Kitty E. Genetic diversity of two salmonid species, Dolly Varden (Salvelinus malma) and coastal cutthroat trout (Oncorhynchus clarki clarki) in Prince William Sound, Alaska were examined at multiple spatial scales with three molecular markers. Pleistocene glaciers covered what is now Prince William Sound 8,000- 12,000 years ago and both species colonized the region subsequently. Because these species have different migratory behavior and historic ranges I expected to see different patterns of genetic diversity within Prince William Sound. Haplotype frequency and nucleotide diversity in sixteen mitochondrial DNA (mtDNA) restriction fragment enzymes combinations in Prince William Sound were higher in Dolly Varden than in coastal cutthroat trout, which were close to fixation. Low estimates of these measures in coastal cutthroat trout may reflect a founder effect resulting from colonization of this region from a single glacial refuge (Cascadia) and low dispersal capacity. To examine if genetic diversity in coastal cutthroat trout was higher in areas of glacial refuge, three additional locations from throughout their distributional range were examined with the same restriction enzymes. Haplotype frequency and nucleotide diversity were lower in areas that were glaciated than estimates of the same measures in a glacial refuge. Again, founder effects during colonization of the three glaciated sites may account for these results. Genetic variation of Dolly Varden and coastal cutthroat trout was also examined within and among populations in Prince William Sound with microsatellites and allozymes. The pattern of genetic variation in coastal cutthroat trout was complex. There was lower genetic diversity within populations that were recently colonized following recent de-glaciation (150-350 ybp). Genetic diversity among some coastal cutthroat trout populations was high, which possibly reflects restricted migration. In other trout populations there was low diversity among populations, possible reflecting historic gene flow. In Dolly Varden, genetic variation among anadromous populations in Prince William Sound was low. There were large differences among resident and anadromous populations. These data provide information for the management for both species, which may reduce the risk of the loss of genetic diversity within local populations. Title: Genetic diversity in coastal cutthroat trout and Dolly Varden in Prince William Sound, Alaska Author: Griswold, Kitty E. Genetic diversity of two salmonid species, Dolly Varden (Salvelinus malma) and coastal cutthroat trout (Oncorhynchus clarki clarki) in Prince William Sound, Alaska were examined at multiple spatial scales with three molecular markers. Pleistocene glaciers covered what is now Prince William Sound 8,000- 12,000 years ago and both species colonized the region subsequently. Because these species have different migratory behavior and historic ranges I expected to see different patterns of genetic diversity within Prince William Sound. Haplotype frequency and nucleotide diversity in sixteen mitochondrial DNA (mtDNA) restriction fragment enzymes combinations in Prince William Sound were higher in Dolly Varden than in coastal cutthroat trout, which were close to fixation. Low estimates of these measures in coastal cutthroat trout may reflect a founder effect resulting from colonization of this region from a single glacial refuge (Cascadia) and low dispersal capacity. To examine if genetic diversity in coastal cutthroat trout was higher in areas of glacial refuge, three additional locations from throughout their distributional range were examined with the same restriction enzymes. Haplotype frequency and nucleotide diversity were lower in areas that were glaciated than estimates of the same measures in a glacial refuge. Again, founder effects during colonization of the three glaciated sites may account for these results. Genetic variation of Dolly Varden and coastal cutthroat trout was also examined within and among populations in Prince William Sound with microsatellites and allozymes. The pattern of genetic variation in coastal cutthroat trout was complex. There was lower genetic diversity within populations that were recently colonized following recent de-glaciation (150-350 ybp). Genetic diversity among some coastal cutthroat trout populations was high, which possibly reflects restricted migration. In other trout populations there was low diversity among populations, possible reflecting historic gene flow. In Dolly Varden, genetic variation among anadromous populations in Prince William Sound was low. There were large differences among resident and anadromous populations. These data provide information for the management for both species, which may reduce the risk of the loss of genetic diversity within local populations. Close

• 87. [Article] Contrasting demographic history and gene flow patterns of two mangrove species on either side of the Central American Isthmus

  This is the publisher’s final pdf. The published article is copyrighted by the author(s) and published by John Wiley & Sons Ltd. The published article can be found at: http://onlinelibrary.wiley.com/jo...

  Citation × Citation Citation Abstract Copy Title: Contrasting demographic history and gene flow patterns of two mangrove species on either side of the Central American Isthmus Author: Cerón‐Souza, Ivania, Schwarzbach, Andrea E., Gonzalez, Elena G. This is the publisher’s final pdf. The published article is copyrighted by the author(s) and published by John Wiley & Sons Ltd. The published article can be found at: http://onlinelibrary.wiley.com/journal/10.1002/%28ISSN%292045-7758 Title: Contrasting demographic history and gene flow patterns of two mangrove species on either side of the Central American Isthmus Author: Cerón‐Souza, Ivania, Schwarzbach, Andrea E., Gonzalez, Elena G. This is the publisher’s final pdf. The published article is copyrighted by the author(s) and published by John Wiley & Sons Ltd. The published article can be found at: http://onlinelibrary.wiley.com/journal/10.1002/%28ISSN%292045-7758 Close

• 88. [Article] Basement and Regional Structure Along Strike of the Queen Charlotte Fault in the Context of Modern and Historical Earthquake Ruptures

  To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by the Seismological ...

  Citation × Citation Citation Abstract Copy Title: Basement and Regional Structure Along Strike of the Queen Charlotte Fault in the Context of Modern and Historical Earthquake Ruptures Author: Walton, Maureen A. L., Roland, Emily C., Gulick, Sean P. S., Haeussler, Peter J., Tréhu, Anne M. To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by the Seismological Society of America and can be found at: http://www.bssaonline.org/. Title: Basement and Regional Structure Along Strike of the Queen Charlotte Fault in the Context of Modern and Historical Earthquake Ruptures Author: Walton, Maureen A. L., Roland, Emily C., Gulick, Sean P. S., Haeussler, Peter J., Tréhu, Anne M. To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by the Seismological Society of America and can be found at: http://www.bssaonline.org/. Close

• 89. [Article] Soil solution chemistry, profile development, and mineral authigenesis in several western Oregon soils

  Clay mineral genesis was studied in soils representative of several different geomorphic surfaces in western Oregon, ranging in age from Pliocene-early Pleistocene to late Pleistocene. Soil solution studies, clay ...

  Citation × Citation Citation Abstract Copy Title: Soil solution chemistry, profile development, and mineral authigenesis in several western Oregon soils Author: Glasmann, Joseph Reed Clay mineral genesis was studied in soils representative of several different geomorphic surfaces in western Oregon, ranging in age from Pliocene-early Pleistocene to late Pleistocene. Soil solution studies, clay mineralogy, and soil raicromorphology were employed to provide evidence of clay mineral synthesis and interpret soil genesis. Soils at each study area were characterized by distinct differences in soil solution chemistry, clay mineralogy, plasmic fabric, and genetic history, although parent material compositions between sites were often similar. Soil solution studies suggested that clay mineral synthesis from solution does not occur in soils representing the oldest geomorphic surface. The cxic soil properties at this location were developed during a prior weathering cycle and the soils are at a genetic endpoint in the present environment. Soil solutions from Ultisols on remnants of Pleistocene surfaces in the Oregon Coast Range were in equilibrium with respect to kaolinite in the solum, but stable with respect to Mg-montmorillonite in the zone characterizing active bedrock weathering. Microraorphological, clay mineralogical, and chemical evidence suggested that alteration of Mgchlorite in sedimentary rocks leads to smectite genesis in the Cr horizon of the Ultisols, followed by conversion of smectite to halloysite and chloritic intergrade in the solum. Alteration of basalt in these soils also leads to the formation of smectite, which is unstable with respect to halloysite in well-drained microenvironments within soil profiles. Soil solutions from soils characteristic of silt-mantled late Pleistocene surfaces on the western margins of the Willamette Valley showed compositional variation from pedon to pedon and horizon to horizon within individual pedons, reflecting the influence of soil parent material compositional variation. Soil solutions were generally in equilibrium with respect to kaolinite, although solutions from horizons developed in tuffaceous sediments were in equilibrium with Mg-montmorillonite. Both kaolinite and smectite were observed as products of mineral authigenesis in these soils. Authigenic clay showed delicate honeycomb or hexagonal morphology in contrast to the parallel oriented appearance of illuvial clays. Andesite alteration in wet, unstable soils of Oregon's western Cascades also resulted in the formation of smectite. The sequence of mineral alteration in andesites is similar to that described for basalts; however, the final products of mineral authigenesis are distinctly microenvironment dependent. Morphologic evidence suggests that chemical properties of bulk soil solutions can not always be considered to represent the solution conditions at the site of mineral authigenesis. In the absence of reliable in situ micro-chemical analytical techniques, detailed micromorphological studies can aid'in interpreting soil microchemical properties at weathering surfaces by revealing the identity of neoformed secondary phases. Title: Soil solution chemistry, profile development, and mineral authigenesis in several western Oregon soils Author: Glasmann, Joseph Reed Clay mineral genesis was studied in soils representative of several different geomorphic surfaces in western Oregon, ranging in age from Pliocene-early Pleistocene to late Pleistocene. Soil solution studies, clay mineralogy, and soil raicromorphology were employed to provide evidence of clay mineral synthesis and interpret soil genesis. Soils at each study area were characterized by distinct differences in soil solution chemistry, clay mineralogy, plasmic fabric, and genetic history, although parent material compositions between sites were often similar. Soil solution studies suggested that clay mineral synthesis from solution does not occur in soils representing the oldest geomorphic surface. The cxic soil properties at this location were developed during a prior weathering cycle and the soils are at a genetic endpoint in the present environment. Soil solutions from Ultisols on remnants of Pleistocene surfaces in the Oregon Coast Range were in equilibrium with respect to kaolinite in the solum, but stable with respect to Mg-montmorillonite in the zone characterizing active bedrock weathering. Microraorphological, clay mineralogical, and chemical evidence suggested that alteration of Mgchlorite in sedimentary rocks leads to smectite genesis in the Cr horizon of the Ultisols, followed by conversion of smectite to halloysite and chloritic intergrade in the solum. Alteration of basalt in these soils also leads to the formation of smectite, which is unstable with respect to halloysite in well-drained microenvironments within soil profiles. Soil solutions from soils characteristic of silt-mantled late Pleistocene surfaces on the western margins of the Willamette Valley showed compositional variation from pedon to pedon and horizon to horizon within individual pedons, reflecting the influence of soil parent material compositional variation. Soil solutions were generally in equilibrium with respect to kaolinite, although solutions from horizons developed in tuffaceous sediments were in equilibrium with Mg-montmorillonite. Both kaolinite and smectite were observed as products of mineral authigenesis in these soils. Authigenic clay showed delicate honeycomb or hexagonal morphology in contrast to the parallel oriented appearance of illuvial clays. Andesite alteration in wet, unstable soils of Oregon's western Cascades also resulted in the formation of smectite. The sequence of mineral alteration in andesites is similar to that described for basalts; however, the final products of mineral authigenesis are distinctly microenvironment dependent. Morphologic evidence suggests that chemical properties of bulk soil solutions can not always be considered to represent the solution conditions at the site of mineral authigenesis. In the absence of reliable in situ micro-chemical analytical techniques, detailed micromorphological studies can aid'in interpreting soil microchemical properties at weathering surfaces by revealing the identity of neoformed secondary phases. Close

• 90. [Article] Chemical element profiles by instrumental neutron activation analysis : in, part 1, two species of wheat bunt spores, Tilletia caries (DC) Tul. and Tilletia controversa Kühn; part 2, representative sediment and basalt samples taken from a DSDP 678 m core, site 525A, Leg 74, Walvis Ridge

  Part 1 The concentration of seventeen elements in two species of fungus which cause wheat bunt disease, Tilletia caries (DC.)Tul. (TS) and Tilletia controversa Kiihn (DS), were determined by instrumental ...

  Citation × Citation Citation Abstract Copy Title: Chemical element profiles by instrumental neutron activation analysis : in, part 1, two species of wheat bunt spores, Tilletia caries (DC) Tul. and Tilletia controversa Kühn; part 2, representative sediment and basalt samples taken from a DSDP 678 m core, site 525A, Leg 74, Walvis Ridge Author: Liu, Yun-gang Part 1 The concentration of seventeen elements in two species of fungus which cause wheat bunt disease, Tilletia caries (DC.)Tul. (TS) and Tilletia controversa Kiihn (DS), were determined by instrumental neutron activation analysis in 37 TS spore samples, and 31 DS spore samples. Aluminum was chosen as a soil contamination indicator to correct for soil contamination. The plot of the concentrations of the ith element [X[subscript i]] versus Al, yielded the biological concentrations of [X.[subscript i]]. The results show that the biological concentrations of Sc, V, La, and Sm are insignificantly small and that their contents in the spores are essentially all derived from soil dust contamination. For Na and Fe, considerable fractions, 0.15 and 0.60, respectively, of their total concentrations are derived from soil contamination. For other elements, the soil contamination contributions are relatively small compared to their biological concentrations. The "student" t-test was used for comparisons of the geometric means of the element concentrations between the TS and DS spore series. The differences between the mean values of Cl, K, Ca, Mn, Zn, and Br for the TS and CS series are not totally due to random errors within the 95% confidence level. The differences for K and Cl between the TS and DS series are large and outside the ±10- limits; therefore, the concentrations of these two elements can be used as reliable criteria for distinguishing these two species. Also, Br may be useful as a diagnostic trace element due to the significant difference between the Br geometric means of the TS and DS spores. Part 2 Forty sediment and four basement basalt samples, taken from a 678 m core drilled by the DSDP (Deep Sea Drilling Project) at Site 525A, Leg 74 (June 10-15, 1980), as well as sixteen selected basalt samples around the south Atlantic Ocean were subjected to instrumental neutron activation analysis. Thirty-two major, minor, and trace elements were determined. The core from the Wavlis Ridge site (2467 m) consisted of 574.6 m of sediment and 103.5 m of basalt. The downcore element concentration profiles and regression analyses show that the rare earth elements (REE) are present in significant amounts in both the carbonate and non-carbonate phases in sediments; Sr is concentrated in the carbonate phase; most of the other elements determined exist mainly in the non-carbonate (mostly clay) phase. The calculated partition coefficients of the REEs between the carbonate phase and the free REE ion concentrations in sea water were high and increased with decreasing REE ionic radii or increasing atomic number from 3.9x10⁶ for La to 15x10⁶ for Lu. Using the partition coefficients of the REEs in the carbonate and non-carbonate (clay) phases, the REE concentrations in Atlantic sea water were calculated, and the results indicate that the lanthanide concentrations have not been changed significantly in south Atlantic sea water over the past 70 m.y.. The Ce anomaly observed in >95% carbonate sediments is related to the Ce⁺³ concentration in sea water; therefore, the Ce anomaly is a redox (reducing-oxidizing) indicator of sea water. (Essentially, >99.99% of soluble Ce in sea water is present as Ce⁺³.) The REE patterns show no Ce depletion in mollusc shell segments from the late Campanian, and a slight Ce depletion in carbonate phases from the late Paleocene sediments. From early Eocene on, the REE patterns in the carbonate phase show a marked Ce depletion, the same as is observed in carbonates from the late Pleistocene to early Holocene (about 0.3 m.y. ago). The abrupt and striking change in the Ce depletion indicates that sea water was anoxic over the Walvis Ridge during the late Campanian. As the gap between northeast South America (northeast Brazil) and west central Africa (near the southwest corner of the upper half of Africa, e.g., near Liberia) widened and the Walvis Ridge subsided between the late Campanian and late Paleocene, sea water flow between the north Atlantic and south Atlantic oceans increased steadily, and gradually flushed out the anoxic water layer over the Walvis Ridge, thereby achieving oxidation conditions at about 54 m.y. ago, that are similar to present day sea water redox conditions: in the world oceans. The chemical compositions of the basement rocks of the core corresponds to alkalic basalts, not MA-Crean Ridge basalts (MORBs). Only a few basement rocks had been recovered from other Walvis Ridge sites. The results add more evidence which supports the hypothesis that the Wavlis Ridge was formed by a series of volcanoes moving over a "hot spot" near the Mid-Atlantic Ridge. These volcanoes migrated eastward as the South American and African continents drifted away. Most of the basalt samples taken from the southeast Brazilian continental margin also are not similar to MORE. From the bulk chemical composition and the REE pattern, one 112 m.y. old basalt has been identified as an early-stage MORB. To date, this is the oldest oceanic tholeiite recovered from the south Atlantic. This direct evidence indicates that the continental split between South America and Africa commenced ≥112 m.y. ago, and is consistent with the suggestion that the rift between the two continents began about 125 m.y. ago. Title: Chemical element profiles by instrumental neutron activation analysis : in, part 1, two species of wheat bunt spores, Tilletia caries (DC) Tul. and Tilletia controversa Kühn; part 2, representative sediment and basalt samples taken from a DSDP 678 m core, site 525A, Leg 74, Walvis Ridge Author: Liu, Yun-gang Part 1 The concentration of seventeen elements in two species of fungus which cause wheat bunt disease, Tilletia caries (DC.)Tul. (TS) and Tilletia controversa Kiihn (DS), were determined by instrumental neutron activation analysis in 37 TS spore samples, and 31 DS spore samples. Aluminum was chosen as a soil contamination indicator to correct for soil contamination. The plot of the concentrations of the ith element [X[subscript i]] versus Al, yielded the biological concentrations of [X.[subscript i]]. The results show that the biological concentrations of Sc, V, La, and Sm are insignificantly small and that their contents in the spores are essentially all derived from soil dust contamination. For Na and Fe, considerable fractions, 0.15 and 0.60, respectively, of their total concentrations are derived from soil contamination. For other elements, the soil contamination contributions are relatively small compared to their biological concentrations. The "student" t-test was used for comparisons of the geometric means of the element concentrations between the TS and DS spore series. The differences between the mean values of Cl, K, Ca, Mn, Zn, and Br for the TS and CS series are not totally due to random errors within the 95% confidence level. The differences for K and Cl between the TS and DS series are large and outside the ±10- limits; therefore, the concentrations of these two elements can be used as reliable criteria for distinguishing these two species. Also, Br may be useful as a diagnostic trace element due to the significant difference between the Br geometric means of the TS and DS spores. Part 2 Forty sediment and four basement basalt samples, taken from a 678 m core drilled by the DSDP (Deep Sea Drilling Project) at Site 525A, Leg 74 (June 10-15, 1980), as well as sixteen selected basalt samples around the south Atlantic Ocean were subjected to instrumental neutron activation analysis. Thirty-two major, minor, and trace elements were determined. The core from the Wavlis Ridge site (2467 m) consisted of 574.6 m of sediment and 103.5 m of basalt. The downcore element concentration profiles and regression analyses show that the rare earth elements (REE) are present in significant amounts in both the carbonate and non-carbonate phases in sediments; Sr is concentrated in the carbonate phase; most of the other elements determined exist mainly in the non-carbonate (mostly clay) phase. The calculated partition coefficients of the REEs between the carbonate phase and the free REE ion concentrations in sea water were high and increased with decreasing REE ionic radii or increasing atomic number from 3.9x10⁶ for La to 15x10⁶ for Lu. Using the partition coefficients of the REEs in the carbonate and non-carbonate (clay) phases, the REE concentrations in Atlantic sea water were calculated, and the results indicate that the lanthanide concentrations have not been changed significantly in south Atlantic sea water over the past 70 m.y.. The Ce anomaly observed in >95% carbonate sediments is related to the Ce⁺³ concentration in sea water; therefore, the Ce anomaly is a redox (reducing-oxidizing) indicator of sea water. (Essentially, >99.99% of soluble Ce in sea water is present as Ce⁺³.) The REE patterns show no Ce depletion in mollusc shell segments from the late Campanian, and a slight Ce depletion in carbonate phases from the late Paleocene sediments. From early Eocene on, the REE patterns in the carbonate phase show a marked Ce depletion, the same as is observed in carbonates from the late Pleistocene to early Holocene (about 0.3 m.y. ago). The abrupt and striking change in the Ce depletion indicates that sea water was anoxic over the Walvis Ridge during the late Campanian. As the gap between northeast South America (northeast Brazil) and west central Africa (near the southwest corner of the upper half of Africa, e.g., near Liberia) widened and the Walvis Ridge subsided between the late Campanian and late Paleocene, sea water flow between the north Atlantic and south Atlantic oceans increased steadily, and gradually flushed out the anoxic water layer over the Walvis Ridge, thereby achieving oxidation conditions at about 54 m.y. ago, that are similar to present day sea water redox conditions: in the world oceans. The chemical compositions of the basement rocks of the core corresponds to alkalic basalts, not MA-Crean Ridge basalts (MORBs). Only a few basement rocks had been recovered from other Walvis Ridge sites. The results add more evidence which supports the hypothesis that the Wavlis Ridge was formed by a series of volcanoes moving over a "hot spot" near the Mid-Atlantic Ridge. These volcanoes migrated eastward as the South American and African continents drifted away. Most of the basalt samples taken from the southeast Brazilian continental margin also are not similar to MORE. From the bulk chemical composition and the REE pattern, one 112 m.y. old basalt has been identified as an early-stage MORB. To date, this is the oldest oceanic tholeiite recovered from the south Atlantic. This direct evidence indicates that the continental split between South America and Africa commenced ≥112 m.y. ago, and is consistent with the suggestion that the rift between the two continents began about 125 m.y. ago. Close

• 91. [Article] Geology of the continental terrace off the central coast of Oregon

  The continental terrace west of Oregon between 43° 50'N and 44° 40' N latitude is 50 to 55 miles wide. It consists of a continental shelf, 16 to 35 miles wide, and a continental slope, 16 to 37 miles wide. ...

  Citation × Citation Citation Abstract Copy Title: Geology of the continental terrace off the central coast of Oregon Author: Maloney, Neil Joseph The continental terrace west of Oregon between 43° 50'N and 44° 40' N latitude is 50 to 55 miles wide. It consists of a continental shelf, 16 to 35 miles wide, and a continental slope, 16 to 37 miles wide. The eastern portion of the shelf is a smooth, sediment covered area that slopes very gently west. The western portion of the shelf contains four rocky bank areas. The banks are topographically irregular and appear to be of structural origin. West of the banks the shelf edge occurs at depths of 71 to 90 fathoms. The continental slope extends from the edge of the shelf to the abyssal plain at depths of 1530 to 1610 fathoms. A smooth upper slope of less than three degrees extending to depths of 117 to 250 fathoms occurs north and south of Heceta Bank. West of Heceta Bank the upper slope is formed by a scarp that slopes 10° to 16° to 560 to 725 fathoms. West of the upper slope there is an area of irregular topography, including benches, hills and scarps, which extends to depths of 380 to 1100 fathoms. The lower part of the slope is formed by a north-striking scarp which is 3000 to 6000 feet high and slopes 04° to 15°. The bathymetry indicates that the continental slope was formed by step-type, block faulting. Sediments form a thin surface layer over much of: the terrace. Detrital sand, similar to the coastal sand, covers the shelf from the shoreline to approximately 50 fathoms. The deeper areas on the shelf and upper part of the slope are covered by glauconitic sands and silts on the topographic highs and olive green, clayey silts in the topographic lows. The intermediate and lower portions of the slope are blanketed with olive-green, clayey silt. In these sediments the sand fraction, which generally comprises less than five percent of the sample, is composed chiefly of diatoms, Foraminifera, Radiolaria, and sponge spicules. Sands are also present on the intermediate and deep portions of the slope. Dredge hauls west of Newport obtained sand composed mainly of detrital grains which may have been derived from an underlying friable sandstone. Thin layers of sand occur in cores from other portions of the slope. These sands may have been derived by down slope movement of sediment from the upper slope and the shelf. Sedimentary rocks of Upper Miocene and Pliocene age crop out on the shelf banks and on the continental slope. The banks consist of a sequence of diatomaceous, clayey siltstones with interbeds and concretions of calcareous siltstones. Glauconite sandstone, gray wacke sandstone, and limestone breccia are exposed along with the siltstone, on the northern end of Heceta Bank. Most of the rocks obtamed from the slope are similar to those from the shelf. Friable, wacke sandstone is exposed on the slope west of Newport. Foraminifera, the sand fraction compositions, and textural analyses all indicate that the sediment forming the siltstones from the shelf were deposited at lower littoral to lower bathyal depths. The sediments forming the rocks were deposited in one or more sedimentary basins during the Miocene and Pliocene. The subsidence continued until the. Late Pliocene when the area began to rise. The area was uplifted as much as 1000 fathoms by the Late Pleistocene when the shelf was eroded by transgressions and regressions resulting from sea level changes. The last rise in sea level resulted in the erosion of the shelf to its present form and the deposition of a thin layer of sediment. Sand is presently being deposited on the shallow areas adjacent to the continent, and silt and clay are being laid down on the slope and the sheltered areas of the outer shelf. Title: Geology of the continental terrace off the central coast of Oregon Author: Maloney, Neil Joseph The continental terrace west of Oregon between 43° 50'N and 44° 40' N latitude is 50 to 55 miles wide. It consists of a continental shelf, 16 to 35 miles wide, and a continental slope, 16 to 37 miles wide. The eastern portion of the shelf is a smooth, sediment covered area that slopes very gently west. The western portion of the shelf contains four rocky bank areas. The banks are topographically irregular and appear to be of structural origin. West of the banks the shelf edge occurs at depths of 71 to 90 fathoms. The continental slope extends from the edge of the shelf to the abyssal plain at depths of 1530 to 1610 fathoms. A smooth upper slope of less than three degrees extending to depths of 117 to 250 fathoms occurs north and south of Heceta Bank. West of Heceta Bank the upper slope is formed by a scarp that slopes 10° to 16° to 560 to 725 fathoms. West of the upper slope there is an area of irregular topography, including benches, hills and scarps, which extends to depths of 380 to 1100 fathoms. The lower part of the slope is formed by a north-striking scarp which is 3000 to 6000 feet high and slopes 04° to 15°. The bathymetry indicates that the continental slope was formed by step-type, block faulting. Sediments form a thin surface layer over much of: the terrace. Detrital sand, similar to the coastal sand, covers the shelf from the shoreline to approximately 50 fathoms. The deeper areas on the shelf and upper part of the slope are covered by glauconitic sands and silts on the topographic highs and olive green, clayey silts in the topographic lows. The intermediate and lower portions of the slope are blanketed with olive-green, clayey silt. In these sediments the sand fraction, which generally comprises less than five percent of the sample, is composed chiefly of diatoms, Foraminifera, Radiolaria, and sponge spicules. Sands are also present on the intermediate and deep portions of the slope. Dredge hauls west of Newport obtained sand composed mainly of detrital grains which may have been derived from an underlying friable sandstone. Thin layers of sand occur in cores from other portions of the slope. These sands may have been derived by down slope movement of sediment from the upper slope and the shelf. Sedimentary rocks of Upper Miocene and Pliocene age crop out on the shelf banks and on the continental slope. The banks consist of a sequence of diatomaceous, clayey siltstones with interbeds and concretions of calcareous siltstones. Glauconite sandstone, gray wacke sandstone, and limestone breccia are exposed along with the siltstone, on the northern end of Heceta Bank. Most of the rocks obtamed from the slope are similar to those from the shelf. Friable, wacke sandstone is exposed on the slope west of Newport. Foraminifera, the sand fraction compositions, and textural analyses all indicate that the sediment forming the siltstones from the shelf were deposited at lower littoral to lower bathyal depths. The sediments forming the rocks were deposited in one or more sedimentary basins during the Miocene and Pliocene. The subsidence continued until the. Late Pliocene when the area began to rise. The area was uplifted as much as 1000 fathoms by the Late Pleistocene when the shelf was eroded by transgressions and regressions resulting from sea level changes. The last rise in sea level resulted in the erosion of the shelf to its present form and the deposition of a thin layer of sediment. Sand is presently being deposited on the shallow areas adjacent to the continent, and silt and clay are being laid down on the slope and the sheltered areas of the outer shelf. Close

• 92. [Article] Bathymetry and structure of San Clemente Island, California, and tectonic implications for the southern California continental borderland

  Five lithologic units, ranging in age from Middle Miocene to Recent, are defined on the basis of continuous seismic reflection profile records. Two of the units are Miocene sedimentary and volcanic rocks ...

  Citation × Citation Citation Abstract Copy Title: Bathymetry and structure of San Clemente Island, California, and tectonic implications for the southern California continental borderland Author: Ridlon, James Barr Five lithologic units, ranging in age from Middle Miocene to Recent, are defined on the basis of continuous seismic reflection profile records. Two of the units are Miocene sedimentary and volcanic rocks that have been truncated to form a major unconformity (post-orogenic surface) related to the most recent major tectonism of the region. The remaining units are post-orogenic unconsolidated sediments. The fault pattern offshore is generally related to that exhibited on the island. The pattern conforms to a wrench-fault system hypothesized by Moody and Hill (1956) modified by a general north-south tensional fracturing. The San Clemente Fault is assumed to be the primary wrench fault of the system. Anomalies in the thicknesses and the structure of the unconsolidated sediment and rock units tend to confirm the structural model. A canyon (Eel Ridge Canyon) off the west side of San Clemente Island appears to have been caused by pivotal faulting and erosion, and represents a boundary between different structural trends north and south. A prominent terrace around the island is postulated to have been wave-cut during and since the Late Pleistocene. The island has been tilted slightly to the west by Recent tectonism. A steep magnetic gradient off the east side of the island is considered the consequence of faulted volcanic flows comprising the island itself and a deep basic rock mass responsible for a large positive magnetic anomaly off the northwest side. Other magnetic anomalies reflect major structural trends. Earthquake epicenter data suggest a recent and possibly cyclical occurrence of fault activity in the northern Continental Borderland region and the study area. Fault offsets at the sea floor and earthquake epicenters along the San Clemente fault zone imply recent adjustments along the fault. Wrench-fault movement resulting from a simple shear or shear couple is considered to have caused the zone of brecciation along the San Clemente Fault and produced the fault-trace curvature so evident in a series of en echelon, northwest-striking major faults of the Borderland. Tensile release during periods of wrench-fault development has been a fundamental factor in the structural development of the Borderland basins. The entire structure of the Continental Borderland is believed to have developed by right-lateral movement along the series of wrench faults. These faults are believed to have resulted from a translation of force by sea-floor spreading originating on the East Pacific Rise in the Gulf of California region. This force is considered to have moved a northern Continental Borderland crustal plate westward by east to west release along major wrench faults bordering the north and south ends of this plate. Sediments, transported along channels developed along faults in the island block, were deposited in basins developed by faulting and folding of the pre-orogenic rocks. Transportation appears to have been by means of turbidity-current flows, sand flows, and slides. A maximum average depositional rate of 35 to 47 centimeters per 1,000 years is estimated for post-orogenic sediments. The following findings are suggested for inclusion in the Neogene history of the island: (1) the top 365 meters of Miocene andesitic lavas were deposited above sea level and tend to become slightly more basic in composition with depth; (2) subsidence of the island region and temporary sea-level stand(s) occurred after the deposition of the volcanic rocks, with possible periods of foundering to about the Late Pliocene; (3) emergence, lengthy subaerial exposure, and a period of partial submergence took place from about Late Pliocene through Early Pleistocene; (4) a north-south compressive force developed or recurred across the Borderland during Late Pliocene, developing the present northwest-southeast and east-west wrench-fault systems that have been intermittently active to the present time; (5) much of the present Borderland topography formed during the Pleistocene to Recent. Title: Bathymetry and structure of San Clemente Island, California, and tectonic implications for the southern California continental borderland Author: Ridlon, James Barr Five lithologic units, ranging in age from Middle Miocene to Recent, are defined on the basis of continuous seismic reflection profile records. Two of the units are Miocene sedimentary and volcanic rocks that have been truncated to form a major unconformity (post-orogenic surface) related to the most recent major tectonism of the region. The remaining units are post-orogenic unconsolidated sediments. The fault pattern offshore is generally related to that exhibited on the island. The pattern conforms to a wrench-fault system hypothesized by Moody and Hill (1956) modified by a general north-south tensional fracturing. The San Clemente Fault is assumed to be the primary wrench fault of the system. Anomalies in the thicknesses and the structure of the unconsolidated sediment and rock units tend to confirm the structural model. A canyon (Eel Ridge Canyon) off the west side of San Clemente Island appears to have been caused by pivotal faulting and erosion, and represents a boundary between different structural trends north and south. A prominent terrace around the island is postulated to have been wave-cut during and since the Late Pleistocene. The island has been tilted slightly to the west by Recent tectonism. A steep magnetic gradient off the east side of the island is considered the consequence of faulted volcanic flows comprising the island itself and a deep basic rock mass responsible for a large positive magnetic anomaly off the northwest side. Other magnetic anomalies reflect major structural trends. Earthquake epicenter data suggest a recent and possibly cyclical occurrence of fault activity in the northern Continental Borderland region and the study area. Fault offsets at the sea floor and earthquake epicenters along the San Clemente fault zone imply recent adjustments along the fault. Wrench-fault movement resulting from a simple shear or shear couple is considered to have caused the zone of brecciation along the San Clemente Fault and produced the fault-trace curvature so evident in a series of en echelon, northwest-striking major faults of the Borderland. Tensile release during periods of wrench-fault development has been a fundamental factor in the structural development of the Borderland basins. The entire structure of the Continental Borderland is believed to have developed by right-lateral movement along the series of wrench faults. These faults are believed to have resulted from a translation of force by sea-floor spreading originating on the East Pacific Rise in the Gulf of California region. This force is considered to have moved a northern Continental Borderland crustal plate westward by east to west release along major wrench faults bordering the north and south ends of this plate. Sediments, transported along channels developed along faults in the island block, were deposited in basins developed by faulting and folding of the pre-orogenic rocks. Transportation appears to have been by means of turbidity-current flows, sand flows, and slides. A maximum average depositional rate of 35 to 47 centimeters per 1,000 years is estimated for post-orogenic sediments. The following findings are suggested for inclusion in the Neogene history of the island: (1) the top 365 meters of Miocene andesitic lavas were deposited above sea level and tend to become slightly more basic in composition with depth; (2) subsidence of the island region and temporary sea-level stand(s) occurred after the deposition of the volcanic rocks, with possible periods of foundering to about the Late Pliocene; (3) emergence, lengthy subaerial exposure, and a period of partial submergence took place from about Late Pliocene through Early Pleistocene; (4) a north-south compressive force developed or recurred across the Borderland during Late Pliocene, developing the present northwest-southeast and east-west wrench-fault systems that have been intermittently active to the present time; (5) much of the present Borderland topography formed during the Pleistocene to Recent. Close

• 93. [Article] Continuous seismic profiling investigation of the southern Oregon continental shelf between Cape Blanco and Coos Bay

  A structure map was constructed of the continental shelf between Cape Blanco and Coos Bay, Oregon, exclusively from an interpretation of approximately 700 km of continuous seismic profiles. At least ten ...

  Citation × Citation Citation Abstract Copy Title: Continuous seismic profiling investigation of the southern Oregon continental shelf between Cape Blanco and Coos Bay Author: Mackay, Angus James A structure map was constructed of the continental shelf between Cape Blanco and Coos Bay, Oregon, exclusively from an interpretation of approximately 700 km of continuous seismic profiles. At least ten discernible seismic units were mapped on the bases of acoustic appearance, lateral continuity, angular unconformities, and faults. The offshore units tentatively were correlated with onshore geology and are believed to range in age from the latest Jurassic to late Pleistocene. The sparker profiles reveal that the continental shelf off southern Oregon has experienced significant late Tertiary and Quaternary accretion due to deposition and tectonic uplift. The oldest rock exposures, believed to be the latest Jurassic in age, crop out on the inner continental shelf on the topographic highs off Cape Blanco and Coquille Point. Erosional remnants of probable Late Cretaceous turbidites and the middle Eocene sandstone beds also are exposed on the bathymetric high on the inner shelf southwest of Cape Arago. The initial emplacement of these three uplifted structural blocks is probably a result of late Eocene wrench faulting of the Port Orford shear zone and of the postulated shear zone at Coquille Point. No other early Tertiary sediments apparently are exposed on this portion of the Oregon continental shelf, but they probably extend seaward at depth on the continental margin. Middle Tertiary strata are believed to be exposed on the outer shelf topographic high southwest of Cape Arago. Sediments of Miocene to Pliocene age were deposited throughout much of the continental shelf that was surveyed. The greatest amount of deposition occurred in a north-south trending basin between Cape Blanco and Coquille Bank. Late to post-Pliocene tectonism uplifted and exposed the older underlying rocks on the inner shelf, which are probably of uppermost Jurassic to middle Tertiary age. These same stresses also deformed the Mio-Pliocene sediments into gently undulating structures on the inner shelf. The greatest deformation occurred on the outer shelf and formed Coquille Bank, a north-south trending, doubly plunging, asymmetrical anticline. The terraces or benches on the upper continental slope to the north and south of the Bank are structural features resulting from the doubly plunging anticline. Eustatic sea level lowerings during the Pleistocene truncated the shelf structures as deep as 130 m below present sea level. The detritus was deposited as a wedge of sediments, which forms an unconformable contact with the underlying strata on the outer shelf and upper slope between Coos Bay and Coquille Bank. In areas of deposition there is no distinct break between the shelf and the upper slope; the former merely merges into the latter in a continuous convex curve. In areas of nondeposition, the edge of the shelf is an erosional and structural feature. A possible buried channel was detected northwest of the mouth of the Coquille River. This sediment filled channel is believed to be an erosional remnant of a former course of the Coquille River during a lower stand of sea level. Title: Continuous seismic profiling investigation of the southern Oregon continental shelf between Cape Blanco and Coos Bay Author: Mackay, Angus James A structure map was constructed of the continental shelf between Cape Blanco and Coos Bay, Oregon, exclusively from an interpretation of approximately 700 km of continuous seismic profiles. At least ten discernible seismic units were mapped on the bases of acoustic appearance, lateral continuity, angular unconformities, and faults. The offshore units tentatively were correlated with onshore geology and are believed to range in age from the latest Jurassic to late Pleistocene. The sparker profiles reveal that the continental shelf off southern Oregon has experienced significant late Tertiary and Quaternary accretion due to deposition and tectonic uplift. The oldest rock exposures, believed to be the latest Jurassic in age, crop out on the inner continental shelf on the topographic highs off Cape Blanco and Coquille Point. Erosional remnants of probable Late Cretaceous turbidites and the middle Eocene sandstone beds also are exposed on the bathymetric high on the inner shelf southwest of Cape Arago. The initial emplacement of these three uplifted structural blocks is probably a result of late Eocene wrench faulting of the Port Orford shear zone and of the postulated shear zone at Coquille Point. No other early Tertiary sediments apparently are exposed on this portion of the Oregon continental shelf, but they probably extend seaward at depth on the continental margin. Middle Tertiary strata are believed to be exposed on the outer shelf topographic high southwest of Cape Arago. Sediments of Miocene to Pliocene age were deposited throughout much of the continental shelf that was surveyed. The greatest amount of deposition occurred in a north-south trending basin between Cape Blanco and Coquille Bank. Late to post-Pliocene tectonism uplifted and exposed the older underlying rocks on the inner shelf, which are probably of uppermost Jurassic to middle Tertiary age. These same stresses also deformed the Mio-Pliocene sediments into gently undulating structures on the inner shelf. The greatest deformation occurred on the outer shelf and formed Coquille Bank, a north-south trending, doubly plunging, asymmetrical anticline. The terraces or benches on the upper continental slope to the north and south of the Bank are structural features resulting from the doubly plunging anticline. Eustatic sea level lowerings during the Pleistocene truncated the shelf structures as deep as 130 m below present sea level. The detritus was deposited as a wedge of sediments, which forms an unconformable contact with the underlying strata on the outer shelf and upper slope between Coos Bay and Coquille Bank. In areas of deposition there is no distinct break between the shelf and the upper slope; the former merely merges into the latter in a continuous convex curve. In areas of nondeposition, the edge of the shelf is an erosional and structural feature. A possible buried channel was detected northwest of the mouth of the Coquille River. This sediment filled channel is believed to be an erosional remnant of a former course of the Coquille River during a lower stand of sea level. Close

• 94. [Article] Seismotectonics in the eastern Precordillera, San Juan, Argentina : reconciling earthquakes and structural geology in the vicinity of the 1944 earthquake for a new model of crustal-scale deformation

  This thesis synthesizes surficial structural data, a detailed analysis of an earthquake in 1944, and historical seismicity into a new model of crustal scale deformation in the eastern Precordillera in ...

  Citation × Citation Citation Abstract Copy Title: Seismotectonics in the eastern Precordillera, San Juan, Argentina : reconciling earthquakes and structural geology in the vicinity of the 1944 earthquake for a new model of crustal-scale deformation Author: Schiffman, Celia Rose This thesis synthesizes surficial structural data, a detailed analysis of an earthquake in 1944, and historical seismicity into a new model of crustal scale deformation in the eastern Precordillera in northwestern Argentina in the vicinity of San Juan. The eastern Precordillera was uplifted during previous thin-skinned deformation episodes, and is currently being overprinted by active structures in the basement. Therefore there is a disconnect between the active basement faults and surficial structures because movement is filtered through previous deformations. The 1944 earthquake is an example of this disconnect: it occurred at 25 km depth on a north-south striking thrust fault, and resulted in northeast-southwest flexural slip related to fold growth at the surface. We used teleseismic long period body waves to invert for parameters such as centroid depth, the source time function, the moment, the strike, dip, and rake of the nodal planes, and type of mechanism. The centroid depth is located at 24 km, the source time function shows one sharp pulse indicating a simple event, the moment equates to a body wave magnitude of 6.76, and the nodal planes are north-south striking, either steeply east- or west-dipping thrust solutions with a small component of right lateral strike slip motion. We prefer the east-dipping plane in the context of isoseismals, other published epicentral locations, microseismicity in the area, and regional structural geology. A suite of progressively abandoned Pleistocene-Holocene fluvial strath terraces has recorded recent deformation, whereas the underlying bedrock of Neogene redbeds and Paleozoic carbonate thrust sheets making up the ranges of the eastern Precordillera has recorded earlier deformational phases. The combination of these three structural levels in space in time show how deformation has progressed from thin-skinned back-thrusting associated with the development of a foreland fold and thrust belt, to fold-growth related deformation associated with movement on underlying thin-skinned thrust sheets, to block uplift and fold-growth associated with basement faults uplifting and deforming previously folded and faulted strata. The source parameters of the 1944 earthquake support the notion of thin-skinned structures being refolded by basement faults, and a crustal-scale model is constructed using structural geology to help constrain the preferred epicentral location of the 1944 earthquake. Title: Seismotectonics in the eastern Precordillera, San Juan, Argentina : reconciling earthquakes and structural geology in the vicinity of the 1944 earthquake for a new model of crustal-scale deformation Author: Schiffman, Celia Rose This thesis synthesizes surficial structural data, a detailed analysis of an earthquake in 1944, and historical seismicity into a new model of crustal scale deformation in the eastern Precordillera in northwestern Argentina in the vicinity of San Juan. The eastern Precordillera was uplifted during previous thin-skinned deformation episodes, and is currently being overprinted by active structures in the basement. Therefore there is a disconnect between the active basement faults and surficial structures because movement is filtered through previous deformations. The 1944 earthquake is an example of this disconnect: it occurred at 25 km depth on a north-south striking thrust fault, and resulted in northeast-southwest flexural slip related to fold growth at the surface. We used teleseismic long period body waves to invert for parameters such as centroid depth, the source time function, the moment, the strike, dip, and rake of the nodal planes, and type of mechanism. The centroid depth is located at 24 km, the source time function shows one sharp pulse indicating a simple event, the moment equates to a body wave magnitude of 6.76, and the nodal planes are north-south striking, either steeply east- or west-dipping thrust solutions with a small component of right lateral strike slip motion. We prefer the east-dipping plane in the context of isoseismals, other published epicentral locations, microseismicity in the area, and regional structural geology. A suite of progressively abandoned Pleistocene-Holocene fluvial strath terraces has recorded recent deformation, whereas the underlying bedrock of Neogene redbeds and Paleozoic carbonate thrust sheets making up the ranges of the eastern Precordillera has recorded earlier deformational phases. The combination of these three structural levels in space in time show how deformation has progressed from thin-skinned back-thrusting associated with the development of a foreland fold and thrust belt, to fold-growth related deformation associated with movement on underlying thin-skinned thrust sheets, to block uplift and fold-growth associated with basement faults uplifting and deforming previously folded and faulted strata. The source parameters of the 1944 earthquake support the notion of thin-skinned structures being refolded by basement faults, and a crustal-scale model is constructed using structural geology to help constrain the preferred epicentral location of the 1944 earthquake. Close

• 95. [Article] A dwarfed population of Catostomus rimiculus (Catostomidae: Pisces) in Jenny Creek, Jackson County, Oregon

  The population of Catostomus rimiculus from Jenny Creek basin is identified as a dwarfed derivative of the normally much larger C. rimiculus from the Klamath and Rogue River systems. C. rimiculus in Jenny ...

  Citation × Citation Citation Abstract Copy Title: A dwarfed population of Catostomus rimiculus (Catostomidae: Pisces) in Jenny Creek, Jackson County, Oregon Author: Hohler, David Berry The population of Catostomus rimiculus from Jenny Creek basin is identified as a dwarfed derivative of the normally much larger C. rimiculus from the Klamath and Rogue River systems. C. rimiculus in Jenny Creek basin are separated from those in the Klamath by a series of 3-10m waterfalls resulting from a Pleistocene lava flow. C. rimiculus in Jenny Creek basin can be distinguished from the Rogue River stock by number of scales above the lateral line, number of pectoral fin rays, number of caudal vertebrae, number of post-Weberian vertebrae and size of the lips. Stocks from Jenny Creek basin and the Klamath can be distinguished on the basis of number of caudal vertebrae. The suckers from Jenny Creek basin mature at approximately 130 mm SL at age II. Only one specimen was older than III. Growth rate appears to be similar in all three stocks of suckers despite the young age of maturity of Jenny Creek suckers. Age at maturity is IV or V for Klamath and Rogue River C. rimiculus. The largest sucker collected from the Jenny Creek basin was 210 mm SL whereas many specimens 250-390 mm SL were collected in the Rogue and Klamath River systems. I hypothesize that fish colonized the Jenny Creek basin by headwater capture in the Skookum-Rocky Creek area. Jenny Creek suckers are opportunistic omnivores. Segregation of foods in the intestine indicate discriminative feeding. Jenny Creek suckers were found in most habitat types in the lower reaches of Jenny, Beaver, Corral, Keene and Johnson Creeks in summer 1979. Sampling throughout the year established a pattern of migration upstream to spawn in spring and movement downstream in fall. Title: A dwarfed population of Catostomus rimiculus (Catostomidae: Pisces) in Jenny Creek, Jackson County, Oregon Author: Hohler, David Berry The population of Catostomus rimiculus from Jenny Creek basin is identified as a dwarfed derivative of the normally much larger C. rimiculus from the Klamath and Rogue River systems. C. rimiculus in Jenny Creek basin are separated from those in the Klamath by a series of 3-10m waterfalls resulting from a Pleistocene lava flow. C. rimiculus in Jenny Creek basin can be distinguished from the Rogue River stock by number of scales above the lateral line, number of pectoral fin rays, number of caudal vertebrae, number of post-Weberian vertebrae and size of the lips. Stocks from Jenny Creek basin and the Klamath can be distinguished on the basis of number of caudal vertebrae. The suckers from Jenny Creek basin mature at approximately 130 mm SL at age II. Only one specimen was older than III. Growth rate appears to be similar in all three stocks of suckers despite the young age of maturity of Jenny Creek suckers. Age at maturity is IV or V for Klamath and Rogue River C. rimiculus. The largest sucker collected from the Jenny Creek basin was 210 mm SL whereas many specimens 250-390 mm SL were collected in the Rogue and Klamath River systems. I hypothesize that fish colonized the Jenny Creek basin by headwater capture in the Skookum-Rocky Creek area. Jenny Creek suckers are opportunistic omnivores. Segregation of foods in the intestine indicate discriminative feeding. Jenny Creek suckers were found in most habitat types in the lower reaches of Jenny, Beaver, Corral, Keene and Johnson Creeks in summer 1979. Sampling throughout the year established a pattern of migration upstream to spawn in spring and movement downstream in fall. Close

• 96. [Article] Geology of the Picture Gorge quadrangle, Oregon

  There are seven stratigraphic units exposed in the Picture Gorge quadrangle, a 204-square mile area in east-central Oregon. isolated exposures of pre-Cretaceous serpentinites, metalimestones, and other ...

  Citation × Citation Citation Abstract Copy Title: Geology of the Picture Gorge quadrangle, Oregon Author: White, Willis Harkness There are seven stratigraphic units exposed in the Picture Gorge quadrangle, a 204-square mile area in east-central Oregon. isolated exposures of pre-Cretaceous serpentinites, metalimestones, and other metamorphic rocks record marine deposition of sands silts, and limy sediments followed by burial, lithification, peridotite intrusion, and several periods of deformation. Intrusion and deformation were accompanied by serpentinization, silcification. and calcite veination. Cretaceous conglomerates and intercalated sandstones, which unconformably overlie the metamorphic rocks, are a result of fluvial deposition in a nearshore or continental environment, burial, lithification, uplift, and erosion. Pebbles were derived from plutonicmetamorphic highlands. The Eocene Clamo Formation unconformably overlies the Cretaceous rocks and is made up of basalt conglomerate, silicified conglomerate, andesite breccias, and andesite flows. The fossiliferous John Day Formation, Oligo-Miocene in age, lies unconformably on the Clamo Formation and is pyroclastic in character. Ash was wind-transported from trachytic-andesitic sources to the west and deposited on land, in lakes, and in swamps. The 2, 400-foot section of volcanic siltstones and waterlaid volcaniclastic rocks includes some basalt near the base and an ash-flow tuff near the middle. The John Day Formation was folded slightly after consolidation. The fissure-fed Middle Mjocene Columbia River Basalt flows, at least 2, 300 feet thick, blanket 124 square miles of the quadrangle. Modal analyses of thin sections from 22 basalt flows suggest that flows cannot be correlated on the basis of mineralogy. Correlation must involve a combination of criteria, such as color, texture, and nature of outcrop, together with mineralogy and chemical analyses. Interfiow breccias, tuffs, volcanic siltstones and sandstones, dikes, and an irregular intrusion are also present. The Columbia River Basalt unconformably overlies the John Day Formation. After emplacement, the basalt flow rocks were folded into the west-trending Sunflower anticline and John Day syncline. Normal faulting occurred on the shared flank of the two folds. The Upper Miocene Mascall Formation lies unconformably upon the Columbia River Basalt. About 400 feet of well-bedded, rhy-. olitic volcanic siltstones and intercalated sand and gravel lenses suggest eoliari and fluvial deposition of ash in lakes and swamps. Folding and faulting occurred along the same trends which were active during Columbia River Basalt time. 'lhe Plio-Pleistocene Rattlesnake Formation rests with pronounced angular unconformity on the Mascall Formation. About 10 feet of poorly consolidated fluvial gravels enclose a 38-foot-thick ash-flow tuff. Pleistocene and recent events include capture of the middle fork of the John Day River, slumping, development of pediments, formation of stone garlands, stone stripes, and talus-free mounds, and deposition of stream gravels. An andesitic, hornblende-bearing white volcanic ash was deposited by wind. Title: Geology of the Picture Gorge quadrangle, Oregon Author: White, Willis Harkness There are seven stratigraphic units exposed in the Picture Gorge quadrangle, a 204-square mile area in east-central Oregon. isolated exposures of pre-Cretaceous serpentinites, metalimestones, and other metamorphic rocks record marine deposition of sands silts, and limy sediments followed by burial, lithification, peridotite intrusion, and several periods of deformation. Intrusion and deformation were accompanied by serpentinization, silcification. and calcite veination. Cretaceous conglomerates and intercalated sandstones, which unconformably overlie the metamorphic rocks, are a result of fluvial deposition in a nearshore or continental environment, burial, lithification, uplift, and erosion. Pebbles were derived from plutonicmetamorphic highlands. The Eocene Clamo Formation unconformably overlies the Cretaceous rocks and is made up of basalt conglomerate, silicified conglomerate, andesite breccias, and andesite flows. The fossiliferous John Day Formation, Oligo-Miocene in age, lies unconformably on the Clamo Formation and is pyroclastic in character. Ash was wind-transported from trachytic-andesitic sources to the west and deposited on land, in lakes, and in swamps. The 2, 400-foot section of volcanic siltstones and waterlaid volcaniclastic rocks includes some basalt near the base and an ash-flow tuff near the middle. The John Day Formation was folded slightly after consolidation. The fissure-fed Middle Mjocene Columbia River Basalt flows, at least 2, 300 feet thick, blanket 124 square miles of the quadrangle. Modal analyses of thin sections from 22 basalt flows suggest that flows cannot be correlated on the basis of mineralogy. Correlation must involve a combination of criteria, such as color, texture, and nature of outcrop, together with mineralogy and chemical analyses. Interfiow breccias, tuffs, volcanic siltstones and sandstones, dikes, and an irregular intrusion are also present. The Columbia River Basalt unconformably overlies the John Day Formation. After emplacement, the basalt flow rocks were folded into the west-trending Sunflower anticline and John Day syncline. Normal faulting occurred on the shared flank of the two folds. The Upper Miocene Mascall Formation lies unconformably upon the Columbia River Basalt. About 400 feet of well-bedded, rhy-. olitic volcanic siltstones and intercalated sand and gravel lenses suggest eoliari and fluvial deposition of ash in lakes and swamps. Folding and faulting occurred along the same trends which were active during Columbia River Basalt time. 'lhe Plio-Pleistocene Rattlesnake Formation rests with pronounced angular unconformity on the Mascall Formation. About 10 feet of poorly consolidated fluvial gravels enclose a 38-foot-thick ash-flow tuff. Pleistocene and recent events include capture of the middle fork of the John Day River, slumping, development of pediments, formation of stone garlands, stone stripes, and talus-free mounds, and deposition of stream gravels. An andesitic, hornblende-bearing white volcanic ash was deposited by wind. Close

• 97. [Article] Prehistoric patterns of economic and technological behavior reflected in the 2004 lithic assemblage of site J69E, Espiritu Santo Island, Baja California Sur

  The La Ballena #3 site J69E is a shell midden located on Espiritu Santo Island in Baja California Sur. Archaeological excavations conducted in the summer of 2004 investigated a midden containing lithic ...

  Citation × Citation Citation Abstract Copy Title: Prehistoric patterns of economic and technological behavior reflected in the 2004 lithic assemblage of site J69E, Espiritu Santo Island, Baja California Sur Author: Ferrell, Luanne R. The La Ballena #3 site J69E is a shell midden located on Espiritu Santo Island in Baja California Sur. Archaeological excavations conducted in the summer of 2004 investigated a midden containing lithic and shell artifacts as well as faunal and human remains. Analysis of the debitage and formed lithic tool assemblage collected from the surface of the site and from subsurface levels reveals a record of hunting and gathering practices associated with late Pleistocene to early Holocene age radiocarbon dates. There are five research goals addressed in this thesis encompassing the characterization of technological behaviors from the 2004 lithic assemblage; evaluating patterns of technology through time; evaluating uses of raw lithic materials; evaluating logistical and economic patterns from the production of lithic tools; and evaluating whether the lithic materials indicate mobility within the island and/or the mainland. Theoretical approaches that deal with the organization of hunter-gatherer subsistence practices are used in conjunction with the results of lithic analyses to determine patterns of past human behaviors. Determinations of lithic raw material types and provenance within the island landscape were conducted using microscopes and remote sensing techniques. Typological and aggregate analytical methods were used to determine tool production, hunter-gatherer mobility, and site function. The results of the analyses show that the people inhabiting site J69E emphasized the production of flakes from a variety of core types that were made into expedient flake tools as well as groundstone manufacture. The remote sensing technologies show that the lithic raw materials were being collected from within the area of La Ballena Bay. Together, these data indicate that the hunter-gatherers living in this area practiced forager logistical and subsistence strategies but with relatively low mobility. The practices follow the expected patterns for marine adaptations in the late period Las Palmas culture, which may have had its roots among the early inhabitants of J69E. Adaptations to early maritime environments have not been significant in the New World; however, from this research we can see that the inhabitants successfully adapted to the environments very early. Title: Prehistoric patterns of economic and technological behavior reflected in the 2004 lithic assemblage of site J69E, Espiritu Santo Island, Baja California Sur Author: Ferrell, Luanne R. The La Ballena #3 site J69E is a shell midden located on Espiritu Santo Island in Baja California Sur. Archaeological excavations conducted in the summer of 2004 investigated a midden containing lithic and shell artifacts as well as faunal and human remains. Analysis of the debitage and formed lithic tool assemblage collected from the surface of the site and from subsurface levels reveals a record of hunting and gathering practices associated with late Pleistocene to early Holocene age radiocarbon dates. There are five research goals addressed in this thesis encompassing the characterization of technological behaviors from the 2004 lithic assemblage; evaluating patterns of technology through time; evaluating uses of raw lithic materials; evaluating logistical and economic patterns from the production of lithic tools; and evaluating whether the lithic materials indicate mobility within the island and/or the mainland. Theoretical approaches that deal with the organization of hunter-gatherer subsistence practices are used in conjunction with the results of lithic analyses to determine patterns of past human behaviors. Determinations of lithic raw material types and provenance within the island landscape were conducted using microscopes and remote sensing techniques. Typological and aggregate analytical methods were used to determine tool production, hunter-gatherer mobility, and site function. The results of the analyses show that the people inhabiting site J69E emphasized the production of flakes from a variety of core types that were made into expedient flake tools as well as groundstone manufacture. The remote sensing technologies show that the lithic raw materials were being collected from within the area of La Ballena Bay. Together, these data indicate that the hunter-gatherers living in this area practiced forager logistical and subsistence strategies but with relatively low mobility. The practices follow the expected patterns for marine adaptations in the late period Las Palmas culture, which may have had its roots among the early inhabitants of J69E. Adaptations to early maritime environments have not been significant in the New World; however, from this research we can see that the inhabitants successfully adapted to the environments very early. Close

• 98. [Article] Sediments of Yaquina Bay, Oregon

  Three realms of deposition, Marine, Fluviatile, and Marine- Fluviatile, are recognized in Yaquina Bay, Oregon, on the basis of sediment texture and mineralogy. The Marine Realm extends 1.5 miles into the ...

  Citation × Citation Citation Abstract Copy Title: Sediments of Yaquina Bay, Oregon Author: Kulm, LaVerne D., 1936- Three realms of deposition, Marine, Fluviatile, and Marine- Fluviatile, are recognized in Yaquina Bay, Oregon, on the basis of sediment texture and mineralogy. The Marine Realm extends 1.5 miles into the entrance of the estuary and is typified by normal marine salinity and vigorous tidal action. Sediments of this realm are similar to those of the adjacent beach and coastal dune sands and consist of well-sorted, subangular to subrounded, fine to medium sand. The immature arkosic sands in this realm are distinguished by the marine suite of heavy minerals which include abundant pyroxenes, primarily hypersthene and diopside, and such metamorphic minerals as kyanite, sillimanite, and staurolite. The Fluviatile Realm occurs at the fresh-water head of the estuary and reaches to a point 6 miles from the entrance, where brackish water conditions prevail. The poorly sorted, angular to subangular sediments of this realm range in grain size from silt to coarse sand. They are somewhat more arkosic than the sands of the Marine Realm and are represented by the fluviatile suite of heavy minerals. This assemblage includes such diagnostic minerals as biotite and muscovite, and hematite and limonite. Diopside is absent, hypersthene is restricted, and there is a marked decrease in the abundance of garnet and the number of metamorphic species, compared with the Marine Realm. The Marine-Fluviatile Realm lies between the Fluviatile and Marine Realms and contains admixtures of sediments of the other two realms. The chief sources of Recent sediments in the Yaquina Bay area are the Tertiary rocks of the central Oregon Coast Range, the Pleistocene marine terrace sands and estuarine deposits near the bay mouth, and the Recent transitory beach and dune sands that flank the bay entrance. Marine sand from the adjacent ocean beaches is transported into the estuary by strong tidal currents to Oneatta Point 6 miles from the entrance. Nearby coastal dune sands are blown into the tidal channel near the mouth of the estuary and onto the southwestern shore of Southbeach Tidal Flat by strong onshore winds. Suspended sediments are contributed by the Yaquina River during periods of high runoff. The type of estuarine system is dependent upon seasonal and annual climatic conditions. Generally, from June to October the system is well-mixed, but it may alternate between a well-mixed to partly-mixed system from November to May. Precipitation recorded at Newport apparently reflects the type of estuarine system present during each month of the year for any given year. Deposition in Yaquina Bay appears to be largely seasonal. Maximum deposition probably occurs in the winter and early spring when river runoff is highest, the littoral drift is from south to north, and the highest velocity winds are from the southwest. At this time, the partly-mixed estuarine system is effective in transporting drifting beach sands into the entrance of the estuary. During the summer, deposition is slight because of the low runoff, southward littoral drift, and northwest winds. The well-mixed estuarine system inhibits the transportation of sediments into the estuary. Known areas of shoaling occur on the bar, in the main channel, and in the turning basin. The shoaled areas have maintained a fairly constant position from 1950 to 1961. Estimated average rate of deposition in the dredged channel is 9.1 inches per year. Marine sand is the principal shoaling material. As a result of jetty construction in 1888, and through subsequent additions, extensive deposition has occurred on the southern ocean beach behind the south jetty. An average estimate of Z74 cubic yards of material accumulated annually during the past 73 years. Title: Sediments of Yaquina Bay, Oregon Author: Kulm, LaVerne D., 1936- Three realms of deposition, Marine, Fluviatile, and Marine- Fluviatile, are recognized in Yaquina Bay, Oregon, on the basis of sediment texture and mineralogy. The Marine Realm extends 1.5 miles into the entrance of the estuary and is typified by normal marine salinity and vigorous tidal action. Sediments of this realm are similar to those of the adjacent beach and coastal dune sands and consist of well-sorted, subangular to subrounded, fine to medium sand. The immature arkosic sands in this realm are distinguished by the marine suite of heavy minerals which include abundant pyroxenes, primarily hypersthene and diopside, and such metamorphic minerals as kyanite, sillimanite, and staurolite. The Fluviatile Realm occurs at the fresh-water head of the estuary and reaches to a point 6 miles from the entrance, where brackish water conditions prevail. The poorly sorted, angular to subangular sediments of this realm range in grain size from silt to coarse sand. They are somewhat more arkosic than the sands of the Marine Realm and are represented by the fluviatile suite of heavy minerals. This assemblage includes such diagnostic minerals as biotite and muscovite, and hematite and limonite. Diopside is absent, hypersthene is restricted, and there is a marked decrease in the abundance of garnet and the number of metamorphic species, compared with the Marine Realm. The Marine-Fluviatile Realm lies between the Fluviatile and Marine Realms and contains admixtures of sediments of the other two realms. The chief sources of Recent sediments in the Yaquina Bay area are the Tertiary rocks of the central Oregon Coast Range, the Pleistocene marine terrace sands and estuarine deposits near the bay mouth, and the Recent transitory beach and dune sands that flank the bay entrance. Marine sand from the adjacent ocean beaches is transported into the estuary by strong tidal currents to Oneatta Point 6 miles from the entrance. Nearby coastal dune sands are blown into the tidal channel near the mouth of the estuary and onto the southwestern shore of Southbeach Tidal Flat by strong onshore winds. Suspended sediments are contributed by the Yaquina River during periods of high runoff. The type of estuarine system is dependent upon seasonal and annual climatic conditions. Generally, from June to October the system is well-mixed, but it may alternate between a well-mixed to partly-mixed system from November to May. Precipitation recorded at Newport apparently reflects the type of estuarine system present during each month of the year for any given year. Deposition in Yaquina Bay appears to be largely seasonal. Maximum deposition probably occurs in the winter and early spring when river runoff is highest, the littoral drift is from south to north, and the highest velocity winds are from the southwest. At this time, the partly-mixed estuarine system is effective in transporting drifting beach sands into the entrance of the estuary. During the summer, deposition is slight because of the low runoff, southward littoral drift, and northwest winds. The well-mixed estuarine system inhibits the transportation of sediments into the estuary. Known areas of shoaling occur on the bar, in the main channel, and in the turning basin. The shoaled areas have maintained a fairly constant position from 1950 to 1961. Estimated average rate of deposition in the dredged channel is 9.1 inches per year. Marine sand is the principal shoaling material. As a result of jetty construction in 1888, and through subsequent additions, extensive deposition has occurred on the southern ocean beach behind the south jetty. An average estimate of Z74 cubic yards of material accumulated annually during the past 73 years. Close

• 99. [Article] Geology, structure, and tectonic history of the Tualatin Basin, northwestern Oregon

  The northwest-trending Neogene Tualatin basin in northwestern Oregon is a pull-apart basin with approximately 750 m of post-middle Miocene structural relief. Gently tilted uplands capped by Columbia River ...

  Citation × Citation Citation Abstract Copy Title: Geology, structure, and tectonic history of the Tualatin Basin, northwestern Oregon Author: Popowski, Thomas Allan The northwest-trending Neogene Tualatin basin in northwestern Oregon is a pull-apart basin with approximately 750 m of post-middle Miocene structural relief. Gently tilted uplands capped by Columbia River Basalt Group surround the synclinal basin on all sides. Integrated gravity, aeromagnetic, and seismic reflection data indicated that the basin is underlain by 3 to 4 km of sub-horizontal, upper lower Eocene to middle Miocene age sedimentary and volcanic rocks. Up to 300 m of Columbia River Basalt overlie these older strata, in turn overlain by up to 400 m of late Miocene to Pleistocene, dominantly fluvio-lacustrine sediments. Late middle Eocene strong oblique convergence across the continental margin generated regional northeast-trending fissures in the forearc through which the Tillamook Volcanics and basalt of Waverly Heights erupted. Sinistral strike-slip faults, including the proto-Gales Creek-Mt. Angel structural zone, segmented the forearc into discrete blocks which rotated clockwise independently. A right-step in the Gales Creek-Mt. Angel system generated northeast-directed folding and faulting adjacent to the restraining bend, deforming rocks as young as upper Tillamook Volcanics. Regional uplift culminated in a late Eocene unconformity which removed the arkosic Spencer Formation northeast of the Gales Creek-Mt. Angel system, prior to subsidence of the forearc and burial by late Eocene and Oligocene tuffaceous sedimentary strata. The distribution of middle Miocene Columbia River Basalt Group flows shows no evidence of a structural or topographic Tualatin basin at that time. The syncline initiated along the present southwestern margin of the basin in late Miocene time, in response to uplift of the Coast Range and Portland Hills anticlines to the southwest and northeast, respectively. A late Pliocene decrease in convergence and consequent relative increase in the oblique component of convergence reactivated the Gales Creek-Mt. Angel structural zone as a dextral shear zone. The right-step acted as a releasing bend, allowing extension, increased subsidence and normal faulting along the basin margins, and volcanism within the basin. Subsequent development of transverse folds and reverse faults, northwest-trending riedel shears, northeast-trending antithetic faults, and basin-marginal normal faults, is consistent with classification of the Tualatin basin as a pull-apart basin in a dextral wrench system. Title: Geology, structure, and tectonic history of the Tualatin Basin, northwestern Oregon Author: Popowski, Thomas Allan The northwest-trending Neogene Tualatin basin in northwestern Oregon is a pull-apart basin with approximately 750 m of post-middle Miocene structural relief. Gently tilted uplands capped by Columbia River Basalt Group surround the synclinal basin on all sides. Integrated gravity, aeromagnetic, and seismic reflection data indicated that the basin is underlain by 3 to 4 km of sub-horizontal, upper lower Eocene to middle Miocene age sedimentary and volcanic rocks. Up to 300 m of Columbia River Basalt overlie these older strata, in turn overlain by up to 400 m of late Miocene to Pleistocene, dominantly fluvio-lacustrine sediments. Late middle Eocene strong oblique convergence across the continental margin generated regional northeast-trending fissures in the forearc through which the Tillamook Volcanics and basalt of Waverly Heights erupted. Sinistral strike-slip faults, including the proto-Gales Creek-Mt. Angel structural zone, segmented the forearc into discrete blocks which rotated clockwise independently. A right-step in the Gales Creek-Mt. Angel system generated northeast-directed folding and faulting adjacent to the restraining bend, deforming rocks as young as upper Tillamook Volcanics. Regional uplift culminated in a late Eocene unconformity which removed the arkosic Spencer Formation northeast of the Gales Creek-Mt. Angel system, prior to subsidence of the forearc and burial by late Eocene and Oligocene tuffaceous sedimentary strata. The distribution of middle Miocene Columbia River Basalt Group flows shows no evidence of a structural or topographic Tualatin basin at that time. The syncline initiated along the present southwestern margin of the basin in late Miocene time, in response to uplift of the Coast Range and Portland Hills anticlines to the southwest and northeast, respectively. A late Pliocene decrease in convergence and consequent relative increase in the oblique component of convergence reactivated the Gales Creek-Mt. Angel structural zone as a dextral shear zone. The right-step acted as a releasing bend, allowing extension, increased subsidence and normal faulting along the basin margins, and volcanism within the basin. Subsequent development of transverse folds and reverse faults, northwest-trending riedel shears, northeast-trending antithetic faults, and basin-marginal normal faults, is consistent with classification of the Tualatin basin as a pull-apart basin in a dextral wrench system. Close

• 100. [Article] Structure and tectonics of the southern Willamette Valley, Oregon

  Surface geology, seismic data, petroleum exploratory well data, and water well data have been used to analyze the structural and tectonic history of the southern Willamette Valley. Tertiary strata beneath ...

  Citation × Citation Citation Abstract Copy Title: Structure and tectonics of the southern Willamette Valley, Oregon Author: Graven, Erik P. Surface geology, seismic data, petroleum exploratory well data, and water well data have been used to analyze the structural and tectonic history of the southern Willamette Valley. Tertiary strata beneath the southern Willamette Valley appear to have had an early Cascade or Clarno volcanic source to the east by the middle Eocene. The Tertiary strata have been deformed into a series of broad north-northeast trending folds and northeast and northwest trending faults which initially developed under east-northeast compression during the middle Eocene and have since been rotated clockwise to their present positions. The cross-cutting pattern of subsurface faults has been complicated by reactivation during the clockwise rotation of Si to its present orientation of north-south. Uplift of the Coast Range prior to emplacement of the Miocene Columbia River Basalt Group (CRBG) produced the gentle east dip of strata beneath the western edge of the Valley and beneath the CRBG in the Salem and Eola Hills. The southern Willamette Valley is controlled by erosion of the relatively incompetent Eugene Formation following emplacement of the CRBG. Neogene sediments deposited after this degradational event suggest that during the late Miocene to Pliocene, the proto-Willamette River flowed east of the Salem Hills before uplift along the Waldo Hills forced its course to the west. This aggradation appears to have been caused by increased uplift of the Coast Range and/or subsidence of the Willamette Valley over the slab bend in the subducting Juan de Fuca plate. Degradational and aggradational periods during the Pleistocene appear to have been caused by readjustment of the Willamette River system to new base levels and changes in sediment supply to the valley. Neotectonic features in the valley include: 1) the Owl Creek fault which is at least Pleistocene in age and possibly younger, 2) the Harrisburg anticline, 3) the Turner fault, and 4) deformation in the North Santiam River basin including the Mill Creek fault. With the exception of the Owl Creek fault, the minimum age of these structures is poorly constrained but is at least post-Miocene and possibly younger. Title: Structure and tectonics of the southern Willamette Valley, Oregon Author: Graven, Erik P. Surface geology, seismic data, petroleum exploratory well data, and water well data have been used to analyze the structural and tectonic history of the southern Willamette Valley. Tertiary strata beneath the southern Willamette Valley appear to have had an early Cascade or Clarno volcanic source to the east by the middle Eocene. The Tertiary strata have been deformed into a series of broad north-northeast trending folds and northeast and northwest trending faults which initially developed under east-northeast compression during the middle Eocene and have since been rotated clockwise to their present positions. The cross-cutting pattern of subsurface faults has been complicated by reactivation during the clockwise rotation of Si to its present orientation of north-south. Uplift of the Coast Range prior to emplacement of the Miocene Columbia River Basalt Group (CRBG) produced the gentle east dip of strata beneath the western edge of the Valley and beneath the CRBG in the Salem and Eola Hills. The southern Willamette Valley is controlled by erosion of the relatively incompetent Eugene Formation following emplacement of the CRBG. Neogene sediments deposited after this degradational event suggest that during the late Miocene to Pliocene, the proto-Willamette River flowed east of the Salem Hills before uplift along the Waldo Hills forced its course to the west. This aggradation appears to have been caused by increased uplift of the Coast Range and/or subsidence of the Willamette Valley over the slab bend in the subducting Juan de Fuca plate. Degradational and aggradational periods during the Pleistocene appear to have been caused by readjustment of the Willamette River system to new base levels and changes in sediment supply to the valley. Neotectonic features in the valley include: 1) the Owl Creek fault which is at least Pleistocene in age and possibly younger, 2) the Harrisburg anticline, 3) the Turner fault, and 4) deformation in the North Santiam River basin including the Mill Creek fault. With the exception of the Owl Creek fault, the minimum age of these structures is poorly constrained but is at least post-Miocene and possibly younger. Close