Search

Search Results

• 61. [Article] Palynological Perspectives on Younger Dryas to Early Holocene Human Ecology at Paisley Caves, Oregon

  The Younger Dryas climatic event is a global phenomenon associated with a 1,000 year return to glacial conditions during the late Pleistocene period between 12,800 and 11,500 cal BP. Because of its significant ...

  Citation × Citation Citation Abstract Copy Title: Palynological Perspectives on Younger Dryas to Early Holocene Human Ecology at Paisley Caves, Oregon Author: Saban, Chantel V. The Younger Dryas climatic event is a global phenomenon associated with a 1,000 year return to glacial conditions during the late Pleistocene period between 12,800 and 11,500 cal BP. Because of its significant effects on paleoenvironmental conditions in some parts of the world, archaeologists commonly seek to assess whether the Younger Dryas climatic event had any measureable influence on prehistoric human societies. The early, well preserved archaeological and paleoenvironmental records held in the Paisley Caves site of Oregon's Northern Great Basin provide an opportunity to examine questions human-environmental interaction at the end of the Pleistocene Epoch. Based on a study of pollen records and artifact frequency in the site's Cave 2 deposits, this thesis reports a positive relationship between artifact deposition and marsh expansion in the Summer Lake sub-basin during the Younger Dryas chronozone. While not indicative of a major change in early forager cultural patterns in the Northern Great Basin, these results provide an important perspective on early settlement patterns and human ecology in the far western region of North America. Title: Palynological Perspectives on Younger Dryas to Early Holocene Human Ecology at Paisley Caves, Oregon Author: Saban, Chantel V. The Younger Dryas climatic event is a global phenomenon associated with a 1,000 year return to glacial conditions during the late Pleistocene period between 12,800 and 11,500 cal BP. Because of its significant effects on paleoenvironmental conditions in some parts of the world, archaeologists commonly seek to assess whether the Younger Dryas climatic event had any measureable influence on prehistoric human societies. The early, well preserved archaeological and paleoenvironmental records held in the Paisley Caves site of Oregon's Northern Great Basin provide an opportunity to examine questions human-environmental interaction at the end of the Pleistocene Epoch. Based on a study of pollen records and artifact frequency in the site's Cave 2 deposits, this thesis reports a positive relationship between artifact deposition and marsh expansion in the Summer Lake sub-basin during the Younger Dryas chronozone. While not indicative of a major change in early forager cultural patterns in the Northern Great Basin, these results provide an important perspective on early settlement patterns and human ecology in the far western region of North America. Close

• 62. [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

• 63. [Article] A 37,000-year record of paleomagnetic and environmental magnetic variability from Burial Lake, Arctic Alaska

  Burial Lake sediments from the Noatak Basin in the northwest Brooks Range of Arctic Alaska (68.43°N, 159.17°W, 21.5 m water depth) provide the oldest continuous lacustrine record of paleo-environmental ...

  Citation × Citation Citation Abstract Copy Title: A 37,000-year record of paleomagnetic and environmental magnetic variability from Burial Lake, Arctic Alaska Author: Dorfman, Jason Michael Burial Lake sediments from the Noatak Basin in the northwest Brooks Range of Arctic Alaska (68.43°N, 159.17°W, 21.5 m water depth) provide the oldest continuous lacustrine record of paleo-environmental change and paleomagnetic secular variation (PSV) in eastern Beringia. A precise radiocarbon chronology, determined through accelerator mass spectrometry (AMS) allows us to independently constrain the region's climatic and geomagnetic evolution over the last ~37,000 years. Progressive alternating field (AF) demagnetization of u-channel samples and additionally acquired physical, geochemical, and rock-magnetic datasets, reveal three distinct lithologic subunits associated with the last glacial period (37.2 - 19.4 ka), the deglacial transition (19.4 - 9.8 ka), and the Holocene (9.8 ka - present). Rock magnetic variability suggests changes in sediment provenance associated with the transition from glacial to interglacial conditions. This is interpreted to result from a variable flux of aeolian derived sediment, and is supported by complimentary internal proxy data from Burial Lake. Other regional paleoclimate data, various glacial chronologies for the Brooks Range, and a relative sea level reconstruction facilitate a discussion of possible local, widespread, and far-field sources of dust, and the time-dependency of potential forcing mechanisms governing its production, availability, transport, and deposition. Results indicate an overall reduction in dust input from the glacial period to the Holocene that is largely attributed to increases in terrestrial and aquatic productivity, warming, and moisture availability, which limited widespread landscape deflation and production of dust. Subaerial continental shelves may have provided significant far-field sources of dust to interior Alaska during the glacial period, that were shut off by sea level inundation following the Last Glacial Maximum (LGM; 19 - 26.5 ka), further contributing to diminishing dust emissions. While glacial activity in the Brooks Range may provide local revenue of dust, activation of those deposits and timing of deposition in Burial Lake often appears to be more directly linked with general aridity, lack of vegetative cover, and increased windiness, rather than glacial advances or retreats. Despite this lithologic complexity, we isolate a stable, single-component characteristic remanent magnetization, carried predominately by low-coercivity (titano)magnetite in the pseudo single-domain (PSD) to multi-domain (MD) magnetic grain size range. We reconstruct directional paleomagnetic secular variation (PSV) over the full length of the record, and relative paleointensity (RPI) for the last ~14,700 years, which are consistent with available regional PSV records and continuous spherical harmonic model outputs. We observe only small deviations from geocentric axial dipole (GAD) predictions during the Holocene, while larger amplitude directional features are prevalent before 10 ka, and inclinations lay significantly shallower than GAD. While this may be related to lithology and the sediment magnetic acquisition process, regional records (including those derived from lava flows) indicate similar Holocene-Pleistocene discrepancies. Following on the "eccentric dipole" hypothesis, subdued secular variation and GAD-like behavior in the Pacific appears confined to the Holocene high-intensity state, showing greater variability as Pleistocene field strength diminishes, and/or the dipole axis is shifted away from the Pacific hemisphere. Long period trends in PSV from in the Alaskan Arctic are also similar in character to far-field sites (e.g., Hawaii and Siberia), suggesting large-scale coherent core-fluid flow regimes, expressed over surface geographical extents >5,000 km, and spanning Holocene-Pleistocene time intervals. The well-dated Burial Lake record fills a significant data gap in the growing Holocene paleomagnetic database, while allowing us to extend our understanding of PSV beyond the Holocene and into the Pleistocene, and continue the development of regional stratigraphic dating curves. Title: A 37,000-year record of paleomagnetic and environmental magnetic variability from Burial Lake, Arctic Alaska Author: Dorfman, Jason Michael Burial Lake sediments from the Noatak Basin in the northwest Brooks Range of Arctic Alaska (68.43°N, 159.17°W, 21.5 m water depth) provide the oldest continuous lacustrine record of paleo-environmental change and paleomagnetic secular variation (PSV) in eastern Beringia. A precise radiocarbon chronology, determined through accelerator mass spectrometry (AMS) allows us to independently constrain the region's climatic and geomagnetic evolution over the last ~37,000 years. Progressive alternating field (AF) demagnetization of u-channel samples and additionally acquired physical, geochemical, and rock-magnetic datasets, reveal three distinct lithologic subunits associated with the last glacial period (37.2 - 19.4 ka), the deglacial transition (19.4 - 9.8 ka), and the Holocene (9.8 ka - present). Rock magnetic variability suggests changes in sediment provenance associated with the transition from glacial to interglacial conditions. This is interpreted to result from a variable flux of aeolian derived sediment, and is supported by complimentary internal proxy data from Burial Lake. Other regional paleoclimate data, various glacial chronologies for the Brooks Range, and a relative sea level reconstruction facilitate a discussion of possible local, widespread, and far-field sources of dust, and the time-dependency of potential forcing mechanisms governing its production, availability, transport, and deposition. Results indicate an overall reduction in dust input from the glacial period to the Holocene that is largely attributed to increases in terrestrial and aquatic productivity, warming, and moisture availability, which limited widespread landscape deflation and production of dust. Subaerial continental shelves may have provided significant far-field sources of dust to interior Alaska during the glacial period, that were shut off by sea level inundation following the Last Glacial Maximum (LGM; 19 - 26.5 ka), further contributing to diminishing dust emissions. While glacial activity in the Brooks Range may provide local revenue of dust, activation of those deposits and timing of deposition in Burial Lake often appears to be more directly linked with general aridity, lack of vegetative cover, and increased windiness, rather than glacial advances or retreats. Despite this lithologic complexity, we isolate a stable, single-component characteristic remanent magnetization, carried predominately by low-coercivity (titano)magnetite in the pseudo single-domain (PSD) to multi-domain (MD) magnetic grain size range. We reconstruct directional paleomagnetic secular variation (PSV) over the full length of the record, and relative paleointensity (RPI) for the last ~14,700 years, which are consistent with available regional PSV records and continuous spherical harmonic model outputs. We observe only small deviations from geocentric axial dipole (GAD) predictions during the Holocene, while larger amplitude directional features are prevalent before 10 ka, and inclinations lay significantly shallower than GAD. While this may be related to lithology and the sediment magnetic acquisition process, regional records (including those derived from lava flows) indicate similar Holocene-Pleistocene discrepancies. Following on the "eccentric dipole" hypothesis, subdued secular variation and GAD-like behavior in the Pacific appears confined to the Holocene high-intensity state, showing greater variability as Pleistocene field strength diminishes, and/or the dipole axis is shifted away from the Pacific hemisphere. Long period trends in PSV from in the Alaskan Arctic are also similar in character to far-field sites (e.g., Hawaii and Siberia), suggesting large-scale coherent core-fluid flow regimes, expressed over surface geographical extents >5,000 km, and spanning Holocene-Pleistocene time intervals. The well-dated Burial Lake record fills a significant data gap in the growing Holocene paleomagnetic database, while allowing us to extend our understanding of PSV beyond the Holocene and into the Pleistocene, and continue the development of regional stratigraphic dating curves. Close

• 64. [Article] The Ore bin ; Vol. 25 No. 4 (April 1963)

  Introduction -- Seismology -- Recording stations -- Travel-time curve -- Main earthquake -- Epicenter and origin time -- Magnitude and intensity -- Depth of focus -- Source motion -- Aftershocks -- Geology ...

  Citation × Citation Citation Abstract Copy Title: The Ore bin ; Vol. 25 No. 4 (April 1963) Author: Dehlinger, Peter, Chiburis, E. F., Bowen, Richard G., Oregon. Dept. of Geology and Mineral Industries, Westphal, Warren H. Introduction -- Seismology -- Recording stations -- Travel-time curve -- Main earthquake -- Epicenter and origin time -- Magnitude and intensity -- Depth of focus -- Source motion -- Aftershocks -- Geology -- Stratigraphy -- Gable Volcanics -- Oligocene marine sedimentary rocks -- Columbia River basalt -- Plio-Pleistocene rocks -- Recent alluvium -- Structure -- Recommendations -- Acknowledgements -- References Title: The Ore bin ; Vol. 25 No. 4 (April 1963) Author: Dehlinger, Peter, Chiburis, E. F., Bowen, Richard G., Oregon. Dept. of Geology and Mineral Industries, Westphal, Warren H. Introduction -- Seismology -- Recording stations -- Travel-time curve -- Main earthquake -- Epicenter and origin time -- Magnitude and intensity -- Depth of focus -- Source motion -- Aftershocks -- Geology -- Stratigraphy -- Gable Volcanics -- Oligocene marine sedimentary rocks -- Columbia River basalt -- Plio-Pleistocene rocks -- Recent alluvium -- Structure -- Recommendations -- Acknowledgements -- References Close

• 65. [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

• 66. [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

• 67. [Article] Geology of the southernmost Deschutes basin, Tumalo quadrangle, Deschutes County, Oregon

  The Tumalo quadrangle lies approximately 30 kilometers behind the Cascade volcanic arc and marks the southernmost extent of continuously exposed Deschutes Formation rocks. Deschutes Formation rocks in ...

  Citation × Citation Citation Abstract Copy Title: Geology of the southernmost Deschutes basin, Tumalo quadrangle, Deschutes County, Oregon Author: McDannel, Angela K. The Tumalo quadrangle lies approximately 30 kilometers behind the Cascade volcanic arc and marks the southernmost extent of continuously exposed Deschutes Formation rocks. Deschutes Formation rocks in the Tumalo quadrangle include late Miocene volcaniclastic sedimentary rocks, ignimbrites and lapillistones, and late Miocene to early Pliocene basalts and basaltic andesites. Volcaniclastic sediment and pyroclastic flows originated from sources west to southwest of the Tumalo area and were the products of Early High Cascade arc volcanism. Most pyroclastic flows and falls had silicic compositions and silicic volcanic material dominated the sedimentary deposits. Intermittent and apparently widespread, high discharge events onto a back-arc alluvial plain deposited tuffaceous sediments, much of which became incipient soils during long periods of subaerial exposure. The close of sedimentation was coincident with the initiation of local volcanism at approximately 5.4 Ma. Several small monogenetic shield volcanoes and cinder cones in the Tumalo area erupted the basalt and basaltic andesite lavas which cap the sedimentary section. The basalts are typically porphyritic and high in A1203. Basaltic andesites are aphyric to sparsely porphyritic, are commonly high in FeO and Ti02, appear younger than the basalts, and are not related to the basalts by simple fractionation. Both lava types have relatively evolved compositions based on their Fe' values. An inlier of older Tertiary rhyodacite lavas known as Cline Buttes lies near the northern boundary of the study and is the only locally exposed pre-Deschutes Formation unit. The southern part of the Tumalo quadrangle marks the boundary between continuously exposed Deschutes Formation rocks to the north and Late High Cascade volcanic units to the south. After a hiatus of approximately 4 million years, deposition in the Tumalo area resumed at approximately 0.6 Ma when pyroclastic flows from the High Cascade Range flowed east and northeast into the Tumalo area to rest disconformably above the Deschutes Formation. A diktytaxitic basalt from Newberry volcano locally overlies the pyroclastic units. Widespread, thick alluvium obscures some 16 km2 of bedrock in the study area and appears to be the result of deposition during high discharge events associated with late Pleistocene to Holocene age glaciation of the High Cascade Range. Some thirty en echelon normal faults of the Tumalo fault zone trend between N15°-35°W and cut Pleistocene and older units in the Tumalo quadrangle. Deschutes Formation basalt and basaltic andesite vents are localized in the fault zone. This suggests volcanism was structurally controlled and that an tensional stress regime with a northeast-southwest least compressive stress orientation prevailed in the Tumalo area between the late Miocene to late Pleistocene. Title: Geology of the southernmost Deschutes basin, Tumalo quadrangle, Deschutes County, Oregon Author: McDannel, Angela K. The Tumalo quadrangle lies approximately 30 kilometers behind the Cascade volcanic arc and marks the southernmost extent of continuously exposed Deschutes Formation rocks. Deschutes Formation rocks in the Tumalo quadrangle include late Miocene volcaniclastic sedimentary rocks, ignimbrites and lapillistones, and late Miocene to early Pliocene basalts and basaltic andesites. Volcaniclastic sediment and pyroclastic flows originated from sources west to southwest of the Tumalo area and were the products of Early High Cascade arc volcanism. Most pyroclastic flows and falls had silicic compositions and silicic volcanic material dominated the sedimentary deposits. Intermittent and apparently widespread, high discharge events onto a back-arc alluvial plain deposited tuffaceous sediments, much of which became incipient soils during long periods of subaerial exposure. The close of sedimentation was coincident with the initiation of local volcanism at approximately 5.4 Ma. Several small monogenetic shield volcanoes and cinder cones in the Tumalo area erupted the basalt and basaltic andesite lavas which cap the sedimentary section. The basalts are typically porphyritic and high in A1203. Basaltic andesites are aphyric to sparsely porphyritic, are commonly high in FeO and Ti02, appear younger than the basalts, and are not related to the basalts by simple fractionation. Both lava types have relatively evolved compositions based on their Fe' values. An inlier of older Tertiary rhyodacite lavas known as Cline Buttes lies near the northern boundary of the study and is the only locally exposed pre-Deschutes Formation unit. The southern part of the Tumalo quadrangle marks the boundary between continuously exposed Deschutes Formation rocks to the north and Late High Cascade volcanic units to the south. After a hiatus of approximately 4 million years, deposition in the Tumalo area resumed at approximately 0.6 Ma when pyroclastic flows from the High Cascade Range flowed east and northeast into the Tumalo area to rest disconformably above the Deschutes Formation. A diktytaxitic basalt from Newberry volcano locally overlies the pyroclastic units. Widespread, thick alluvium obscures some 16 km2 of bedrock in the study area and appears to be the result of deposition during high discharge events associated with late Pleistocene to Holocene age glaciation of the High Cascade Range. Some thirty en echelon normal faults of the Tumalo fault zone trend between N15°-35°W and cut Pleistocene and older units in the Tumalo quadrangle. Deschutes Formation basalt and basaltic andesite vents are localized in the fault zone. This suggests volcanism was structurally controlled and that an tensional stress regime with a northeast-southwest least compressive stress orientation prevailed in the Tumalo area between the late Miocene to late Pleistocene. Close

• 68. [Article] Morphological variation in the clouded salamander, Aneides ferreus (Cope) (Amphibia: Caudata: Plethodontidae)

  Multivariate morphometric analyses performed on ten populations of Aneides ferreus indicate that phenotypic expression in this species is exceedingly similar, but that on a fine scale there is considerable significant ...

  Citation × Citation Citation Abstract Copy Title: Morphological variation in the clouded salamander, Aneides ferreus (Cope) (Amphibia: Caudata: Plethodontidae) Author: Beatty, Joseph J. Multivariate morphometric analyses performed on ten populations of Aneides ferreus indicate that phenotypic expression in this species is exceedingly similar, but that on a fine scale there is considerable significant heterogeneity between most populations as well as between regional groups of populations. in terms of variation between California, Oregon, and Vancouver Island specimens. California is differentiated from Vancouver Island at of 2.13; Oregon-California D² of 2.13; Oregon-California D² = 1.35, and Oregon-Vancouver Island exhibited D² of 1.38. These values represent significant F-ratio comparisons at p <<.01. These slight but significant differences in phenotypic expression are not unexpected for a species which ranges over such a wide and varied geographic area, and can be correlated with major topographic features of the Pacific Northwest. Prior to Pleistocene glaciation, populations of A. ferreus were probably continuous throughout northwestern California, western Oregon and Washington, as well as Vancouver Island and British Columbia. As Cordilleran ice advanced and inundated most of British Columbia, and Vancouver Island, populations became isolated in refugia on Vancouver Island, and were probably extirpated from British Columbia proper. The slight, but significant levels of heterogeneity produced from comparisons of Vancouver Island specimens with California and Oregon specimens indicate that the observed disjunction between Vancouver Island populations and those inhabiting coterminous U.S. is probably a relatively recent occurrence, correlating well with events produced by the Fraser Glaciation approximately 15,000 yr BP. Since other plethodontids inhabit Vancouver Island and Washington it is impossible to utilize Pleistocene glaciation as a direct causal mechanism which produced the disjunction, accounting for the absence of A. ferreus in Washington. On a finer scale, significant phenotypic dissimilarity was found to exist between a majority of the pairwise comparisons between populations within each of the three regions. Patterns of heterogeneity within California populations are consistent with predictions derived by utilizing a model based upon a gradual latitudinal environmental dine. No apparent pattern can be seen when pairwise comparisons are made between Oregon populations, although all populations exhibit slight but significant levels of heterogeneity. The effects of Pleistocene climatic events upon California and Oregon populations were probably slight since the maximum southern incursion of Cordilleran ice reached latitudes just south of Olympia, Washington. Montaine glaciers in the Klamath-Siskiyou Mountains provided potential barriers to gene flow between California and Oregon populations until about 10,000 yr BP. The equable redwood forest ecosystem in northwestern California must be considered to be the ancestral habitat for Aneides in general and A. ferreus in particular. Specimens from this region exhibit high tooth counts, a character that has been considered to be primitive by Wake (1963; 1966). Also, all three western Aneides occur in sympatry in northwestern California redwood associations, and the earliest known fossil Aneides were associated with redwood forests during Eocene times in Montana. Comparison of morphological relationships with electrophoretic and chromosomal data for each region and population indicates that there is little agreement between morphological and electrophoretic relationships, but that karyotypic variation is present which allows classification of a collection of individuals to one of the three regions with a high degree of certainty. Title: Morphological variation in the clouded salamander, Aneides ferreus (Cope) (Amphibia: Caudata: Plethodontidae) Author: Beatty, Joseph J. Multivariate morphometric analyses performed on ten populations of Aneides ferreus indicate that phenotypic expression in this species is exceedingly similar, but that on a fine scale there is considerable significant heterogeneity between most populations as well as between regional groups of populations. in terms of variation between California, Oregon, and Vancouver Island specimens. California is differentiated from Vancouver Island at of 2.13; Oregon-California D² of 2.13; Oregon-California D² = 1.35, and Oregon-Vancouver Island exhibited D² of 1.38. These values represent significant F-ratio comparisons at p <<.01. These slight but significant differences in phenotypic expression are not unexpected for a species which ranges over such a wide and varied geographic area, and can be correlated with major topographic features of the Pacific Northwest. Prior to Pleistocene glaciation, populations of A. ferreus were probably continuous throughout northwestern California, western Oregon and Washington, as well as Vancouver Island and British Columbia. As Cordilleran ice advanced and inundated most of British Columbia, and Vancouver Island, populations became isolated in refugia on Vancouver Island, and were probably extirpated from British Columbia proper. The slight, but significant levels of heterogeneity produced from comparisons of Vancouver Island specimens with California and Oregon specimens indicate that the observed disjunction between Vancouver Island populations and those inhabiting coterminous U.S. is probably a relatively recent occurrence, correlating well with events produced by the Fraser Glaciation approximately 15,000 yr BP. Since other plethodontids inhabit Vancouver Island and Washington it is impossible to utilize Pleistocene glaciation as a direct causal mechanism which produced the disjunction, accounting for the absence of A. ferreus in Washington. On a finer scale, significant phenotypic dissimilarity was found to exist between a majority of the pairwise comparisons between populations within each of the three regions. Patterns of heterogeneity within California populations are consistent with predictions derived by utilizing a model based upon a gradual latitudinal environmental dine. No apparent pattern can be seen when pairwise comparisons are made between Oregon populations, although all populations exhibit slight but significant levels of heterogeneity. The effects of Pleistocene climatic events upon California and Oregon populations were probably slight since the maximum southern incursion of Cordilleran ice reached latitudes just south of Olympia, Washington. Montaine glaciers in the Klamath-Siskiyou Mountains provided potential barriers to gene flow between California and Oregon populations until about 10,000 yr BP. The equable redwood forest ecosystem in northwestern California must be considered to be the ancestral habitat for Aneides in general and A. ferreus in particular. Specimens from this region exhibit high tooth counts, a character that has been considered to be primitive by Wake (1963; 1966). Also, all three western Aneides occur in sympatry in northwestern California redwood associations, and the earliest known fossil Aneides were associated with redwood forests during Eocene times in Montana. Comparison of morphological relationships with electrophoretic and chromosomal data for each region and population indicates that there is little agreement between morphological and electrophoretic relationships, but that karyotypic variation is present which allows classification of a collection of individuals to one of the three regions with a high degree of certainty. Close

• 69. [Article] Searching for early archaeological sites along the central Oregon coast : a case study from Neptune State Park (35LA3), Lane County, Oregon

  Locating archaeological sites that predate the arrival of modern sea level has been difficult along the Oregon coast. This is in part believed to be the result of geologic processes that have influenced ...

  Citation × Citation Citation Abstract Copy Title: Searching for early archaeological sites along the central Oregon coast : a case study from Neptune State Park (35LA3), Lane County, Oregon Author: Jenevein, Steve Locating archaeological sites that predate the arrival of modern sea level has been difficult along the Oregon coast. This is in part believed to be the result of geologic processes that have influenced the preservation, distribution, and visibility of sites within the Oregon coastal landscape. Because of these changes, researchers have a poor understanding of where sites that predate modern sea level are located within the modern landscape. Geoarchaeological techniques and concepts are well suited to address these types of questions and can help place the fragments of a once much larger paleocoastal landscape into a modern context. In this thesis I use a Geographic Information System (GIS) and geoarchaeological field and laboratory techniques and concepts to conceptualize, locate, and evaluate landforms located within both the paleo and modern central Oregon coastal landscapes. Geoarchaeological investigations conducted as part of this project at the Neptune Site (35LA3) identified mid to late Holocene aged archaeological materials in addition to an erosional contact located between late Pleistocene and Holocene-aged deposits representing the loss of up to 11,400 years of stratigraphic time. To account for this loss of time, a model of landscape change that is occurring at 35LA3 is presented. Depositional sequences such as truncated late Pleistocene aged deposits that underlie mid to late Holocene sediment that are observed at the Neptune Site are similar to, and have been associated with other early sites along the Oregon coast. The identification of these types of deposits and their associated erosional features may serve as key target horizons for future coastal researchers looking for landforms and archaeological deposits and date to the late Pleistocene to mid Holocene. Title: Searching for early archaeological sites along the central Oregon coast : a case study from Neptune State Park (35LA3), Lane County, Oregon Author: Jenevein, Steve Locating archaeological sites that predate the arrival of modern sea level has been difficult along the Oregon coast. This is in part believed to be the result of geologic processes that have influenced the preservation, distribution, and visibility of sites within the Oregon coastal landscape. Because of these changes, researchers have a poor understanding of where sites that predate modern sea level are located within the modern landscape. Geoarchaeological techniques and concepts are well suited to address these types of questions and can help place the fragments of a once much larger paleocoastal landscape into a modern context. In this thesis I use a Geographic Information System (GIS) and geoarchaeological field and laboratory techniques and concepts to conceptualize, locate, and evaluate landforms located within both the paleo and modern central Oregon coastal landscapes. Geoarchaeological investigations conducted as part of this project at the Neptune Site (35LA3) identified mid to late Holocene aged archaeological materials in addition to an erosional contact located between late Pleistocene and Holocene-aged deposits representing the loss of up to 11,400 years of stratigraphic time. To account for this loss of time, a model of landscape change that is occurring at 35LA3 is presented. Depositional sequences such as truncated late Pleistocene aged deposits that underlie mid to late Holocene sediment that are observed at the Neptune Site are similar to, and have been associated with other early sites along the Oregon coast. The identification of these types of deposits and their associated erosional features may serve as key target horizons for future coastal researchers looking for landforms and archaeological deposits and date to the late Pleistocene to mid Holocene. Close

• 70. [Article] Moletrack scarps to mountains: Quaternary tectonics of the central Alaska Range

  xvi, 121 p. : ill. (some col.), maps (some col.) Also includes two large-scale maps in two separate pdf files. A print copy of this thesis is available through the UO Libraries. Search the library catalog ...

  Citation × Citation Citation Abstract Copy Title: Moletrack scarps to mountains: Quaternary tectonics of the central Alaska Range Author: Bemis, Sean Patrick, 1979- Year: 2010 xvi, 121 p. : ill. (some col.), maps (some col.) Also includes two large-scale maps in two separate pdf files. A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number. Title: Moletrack scarps to mountains: Quaternary tectonics of the central Alaska Range Author: Bemis, Sean Patrick, 1979- Year: 2010 xvi, 121 p. : ill. (some col.), maps (some col.) Also includes two large-scale maps in two separate pdf files. A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number. Close