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• 31. [Article] Stratigraphy, sedimentology, and petrology of neogene rocks in the Deschutes basin, central Oregon : a record of continental-margin volcanism and its influence on fluvial sedimentation in an arc-adjacent basin

  Neogene rocks of the Deschutes basin include the middle Miocene Columbia River Basalt Group and Simtustus Formation, and late Miocene to early Pliocene Deschutes Formation. Assignment of Prineville chemical-type ...

  Citation × Citation Citation Abstract Copy Title: Stratigraphy, sedimentology, and petrology of neogene rocks in the Deschutes basin, central Oregon : a record of continental-margin volcanism and its influence on fluvial sedimentation in an arc-adjacent basin Author: Smith, Gary Allen Neogene rocks of the Deschutes basin include the middle Miocene Columbia River Basalt Group and Simtustus Formation, and late Miocene to early Pliocene Deschutes Formation. Assignment of Prineville chemical-type flows to the Grande Ronde Basalt of the Columbia River Basalt Group is based upon correlation of these lavas from their type area, through the Deschutes basin, and onto the Columbia Plateau where they have been previously mapped as Grande Ronde Basalt. Simtustus Formation is a newly defined unit intercalated with and conformable upon these basalts and is unconformably overlain by Deschutes Formation. Burial of mature topography by middle Miocene basalts raised local base levels and initiated aggradation by low-gradient streams within the basin represented by the tuffaceous sandstones and mudstones of the Simtustus Formation. These sediments are enriched in pyroclastic constituents relative to contemporary Western Cascades volcanics reflecting preferential incorporation of easily eroded and more widespread pyroclastic debris in distal sedimentary sequences compared to epiclastic contributions from lavas. Following a 5 to 7 m.y. hiatus, aggradation was renewed at about 7.5 Ma when coarse-grained volcanogenic sediments, lava flows and ignimbrites from the early High Cascades entered the basin for 2 m.y. The proximal Deschutes Formation is primarily basalt and basaltic andesite lava flows but andesite to rhyolite ignimbrites are the primary volcanic constitutents in the sedimentary-dominated section farther east. Deposition on a broad, eastward-tapering alluvial plain was by debris flows, sheetfloods, and hyperconcentrated flood flows. Episodic aggradation correlates to periods of sediment influx following eruptions' of widespread pyroclastic debris and was separated by periods of incision. The abundance of basalts, combined with the paucity of hydrous minerals and FeO and TiO₂ enrichment in intermediate lavas characterize early High Cascade yolcanics as atypical for convergent-margin arcs. These petrologic characteristics are consistent with high-level fractionation in an extensional regime. Extension culminated in the development of an intra-arc graben which ended Deschutes Formation deposition by structurally isolating the basin from the High Cascade source area. Intra-arc extension may represent invasion of Basin and Range tectonism into the Cascades, or may relate to plate-margin processes, particularly decreasing convergence rate and highly oblique convergence vector. Title: Stratigraphy, sedimentology, and petrology of neogene rocks in the Deschutes basin, central Oregon : a record of continental-margin volcanism and its influence on fluvial sedimentation in an arc-adjacent basin Author: Smith, Gary Allen Neogene rocks of the Deschutes basin include the middle Miocene Columbia River Basalt Group and Simtustus Formation, and late Miocene to early Pliocene Deschutes Formation. Assignment of Prineville chemical-type flows to the Grande Ronde Basalt of the Columbia River Basalt Group is based upon correlation of these lavas from their type area, through the Deschutes basin, and onto the Columbia Plateau where they have been previously mapped as Grande Ronde Basalt. Simtustus Formation is a newly defined unit intercalated with and conformable upon these basalts and is unconformably overlain by Deschutes Formation. Burial of mature topography by middle Miocene basalts raised local base levels and initiated aggradation by low-gradient streams within the basin represented by the tuffaceous sandstones and mudstones of the Simtustus Formation. These sediments are enriched in pyroclastic constituents relative to contemporary Western Cascades volcanics reflecting preferential incorporation of easily eroded and more widespread pyroclastic debris in distal sedimentary sequences compared to epiclastic contributions from lavas. Following a 5 to 7 m.y. hiatus, aggradation was renewed at about 7.5 Ma when coarse-grained volcanogenic sediments, lava flows and ignimbrites from the early High Cascades entered the basin for 2 m.y. The proximal Deschutes Formation is primarily basalt and basaltic andesite lava flows but andesite to rhyolite ignimbrites are the primary volcanic constitutents in the sedimentary-dominated section farther east. Deposition on a broad, eastward-tapering alluvial plain was by debris flows, sheetfloods, and hyperconcentrated flood flows. Episodic aggradation correlates to periods of sediment influx following eruptions' of widespread pyroclastic debris and was separated by periods of incision. The abundance of basalts, combined with the paucity of hydrous minerals and FeO and TiO₂ enrichment in intermediate lavas characterize early High Cascade yolcanics as atypical for convergent-margin arcs. These petrologic characteristics are consistent with high-level fractionation in an extensional regime. Extension culminated in the development of an intra-arc graben which ended Deschutes Formation deposition by structurally isolating the basin from the High Cascade source area. Intra-arc extension may represent invasion of Basin and Range tectonism into the Cascades, or may relate to plate-margin processes, particularly decreasing convergence rate and highly oblique convergence vector. Close

• 32. [Article] Pacific lamprey Entosphenus tridentatus : integrating traditional ecological knowledge and contemporary values into conservation planning, and stream substrate associations with larval abundance in the Willamette River Basin, Oregon, U.S.A.

  Pacific lamprey Entosphenus tridentatus is a valuable icon and traditional food source for Indigenous people of western North America. Native Americans have utilized traditional ecological knowledge (TEK) ...

  Citation × Citation Citation Abstract Copy Title: Pacific lamprey Entosphenus tridentatus : integrating traditional ecological knowledge and contemporary values into conservation planning, and stream substrate associations with larval abundance in the Willamette River Basin, Oregon, U.S.A. Author: Sheoships, Gabe Pacific lamprey Entosphenus tridentatus is a valuable icon and traditional food source for Indigenous people of western North America. Native Americans have utilized traditional ecological knowledge (TEK) since time immemorial to guide their ways of life, transmitting cultural values and natural history to further generational knowledge. Pacific lamprey are in decline throughout their range, and have historically been disregarded in western science. The Willamette River Basin, Oregon, U.S.A currently supports a traditional harvest location, Willamette Falls, which continues to persist, despite great losses in adjacent basins and remains a harvest stronghold amongst Columbia River Basin Tribes. To further understand Pacific lamprey, we utilized both Indigenous knowledge and western science to gain information that would aid recovery. My first goal was to determine traditional ecological knowledge and the cultural values of Pacific lamprey to provide guidance for future conservation planning. My second goal was to evaluate the fine scale habitat characteristics of larval Pacific lamprey. To determine tribal values for the purpose of informing conservation planning of Pacific lamprey, I used: 1) oral history interviews of tribal elders, and 2) questionnaires distributed across entire adult (18 years and older) tribal populations. We conducted semi-structured interviews with tribal elders to gain insights into the biology, distribution, and cultural value of lamprey. I interviewed 32 tribal elders, 11 from the Grand Ronde, 10 from the Siletz, and 11 from the Umatilla. To understand modern fishing practices and current values of lamprey, I distributed a standardized questionnaire (n = 753) to a sample of each adult (18 years and older) tribal population, and received a total of 188 responses total: 38 from the Grand Ronde, 60 from the Siletz, and 90 from the Umatilla. From my interviews, I found that each tribe has noticed a decline in Pacific lamprey populations within their ceded areas, and has witnessed traditional harvest locations lost due to population declines and/or anthropogenic damage, leaving Willamette Falls as the sole harvest site for the three tribes. Questionnaire results showed that the strongest issues relating to the traditional usage of Pacific lamprey amongst each tribe are cultural awareness, harvest accessibility, and Pacific lamprey populations. I evaluated two fine scale habitat associations of larval Pacific lamprey in the Willamette River Basin to understand the association of stream sediment and larval abundance. Study objectives were to: 1) evaluate the substrate size most closely associated with larval abundance, and 2) to evaluate the influence of organic material upon larval abundance. We used a backpack electrofisher to enumerate larval lamprey in six wadeable Willamette River tributaries, using a nested two-pass sample design at a lower, middle, and upper reach (each reach composed of ten 1-m² quadrats). Stream sediment cores were collected for subsequent determination of particle size and organic composition content. I used particle size sieve analysis to estimate dominant substrate size class per sample, from the following size classes: silt (< 0.063 mm), very fine sand (0.063–0.125 mm), fine sand (0.125-0.25 mm), medium fine sand (0.25-0.50 mm), coarse sand (0.50-1.0 mm), very coarse sand (1.0-2.36 mm), and fine gravel (>2.36 mm). I analyzed organic content by loss of weight through combustion. Larvae were present in 17 of 18 reaches (94%) 18), but only detected in 37% of the quadrats. Larval Pacific lamprey abundance was highest in habitats with predominantly medium fine sand (0.25-0.50 mm) substrate. I fit negative binomial mixed models using parameters for sediment depth, percentage of medium fine sand (0.25-0.50 mm), organic material and a random effect for basin. My top model consisted of percentage of medium fine sand (0.25-0.50 mm), organic material and a random effect for basin. At the fine scale, substrate characteristics were associated with the abundance of larval Pacific lamprey. Appropriate conservation measures should be taken to address the restoration of Pacific lamprey, activities that promote natural river flow and distribution of sediment could be of benefit. Efforts that educate mainstream society should be implemented to reduce further species decline. With the continued decline of Pacific lamprey, there is potential for further degradation of tribal cultural values. Conservation work that promotes the restoration of Pacific lamprey is crucial to the tradition and culture of the Grand Ronde, Siletz, and Umatilla Tribes. Title: Pacific lamprey Entosphenus tridentatus : integrating traditional ecological knowledge and contemporary values into conservation planning, and stream substrate associations with larval abundance in the Willamette River Basin, Oregon, U.S.A. Author: Sheoships, Gabe Pacific lamprey Entosphenus tridentatus is a valuable icon and traditional food source for Indigenous people of western North America. Native Americans have utilized traditional ecological knowledge (TEK) since time immemorial to guide their ways of life, transmitting cultural values and natural history to further generational knowledge. Pacific lamprey are in decline throughout their range, and have historically been disregarded in western science. The Willamette River Basin, Oregon, U.S.A currently supports a traditional harvest location, Willamette Falls, which continues to persist, despite great losses in adjacent basins and remains a harvest stronghold amongst Columbia River Basin Tribes. To further understand Pacific lamprey, we utilized both Indigenous knowledge and western science to gain information that would aid recovery. My first goal was to determine traditional ecological knowledge and the cultural values of Pacific lamprey to provide guidance for future conservation planning. My second goal was to evaluate the fine scale habitat characteristics of larval Pacific lamprey. To determine tribal values for the purpose of informing conservation planning of Pacific lamprey, I used: 1) oral history interviews of tribal elders, and 2) questionnaires distributed across entire adult (18 years and older) tribal populations. We conducted semi-structured interviews with tribal elders to gain insights into the biology, distribution, and cultural value of lamprey. I interviewed 32 tribal elders, 11 from the Grand Ronde, 10 from the Siletz, and 11 from the Umatilla. To understand modern fishing practices and current values of lamprey, I distributed a standardized questionnaire (n = 753) to a sample of each adult (18 years and older) tribal population, and received a total of 188 responses total: 38 from the Grand Ronde, 60 from the Siletz, and 90 from the Umatilla. From my interviews, I found that each tribe has noticed a decline in Pacific lamprey populations within their ceded areas, and has witnessed traditional harvest locations lost due to population declines and/or anthropogenic damage, leaving Willamette Falls as the sole harvest site for the three tribes. Questionnaire results showed that the strongest issues relating to the traditional usage of Pacific lamprey amongst each tribe are cultural awareness, harvest accessibility, and Pacific lamprey populations. I evaluated two fine scale habitat associations of larval Pacific lamprey in the Willamette River Basin to understand the association of stream sediment and larval abundance. Study objectives were to: 1) evaluate the substrate size most closely associated with larval abundance, and 2) to evaluate the influence of organic material upon larval abundance. We used a backpack electrofisher to enumerate larval lamprey in six wadeable Willamette River tributaries, using a nested two-pass sample design at a lower, middle, and upper reach (each reach composed of ten 1-m² quadrats). Stream sediment cores were collected for subsequent determination of particle size and organic composition content. I used particle size sieve analysis to estimate dominant substrate size class per sample, from the following size classes: silt (< 0.063 mm), very fine sand (0.063–0.125 mm), fine sand (0.125-0.25 mm), medium fine sand (0.25-0.50 mm), coarse sand (0.50-1.0 mm), very coarse sand (1.0-2.36 mm), and fine gravel (>2.36 mm). I analyzed organic content by loss of weight through combustion. Larvae were present in 17 of 18 reaches (94%) 18), but only detected in 37% of the quadrats. Larval Pacific lamprey abundance was highest in habitats with predominantly medium fine sand (0.25-0.50 mm) substrate. I fit negative binomial mixed models using parameters for sediment depth, percentage of medium fine sand (0.25-0.50 mm), organic material and a random effect for basin. My top model consisted of percentage of medium fine sand (0.25-0.50 mm), organic material and a random effect for basin. At the fine scale, substrate characteristics were associated with the abundance of larval Pacific lamprey. Appropriate conservation measures should be taken to address the restoration of Pacific lamprey, activities that promote natural river flow and distribution of sediment could be of benefit. Efforts that educate mainstream society should be implemented to reduce further species decline. With the continued decline of Pacific lamprey, there is potential for further degradation of tribal cultural values. Conservation work that promotes the restoration of Pacific lamprey is crucial to the tradition and culture of the Grand Ronde, Siletz, and Umatilla Tribes. Close

• 33. [Article] Foodways at Fort Yamhill, 1856-1866 : an archaeological and archival perspective

  Fort Yamhill, located in the eastern foothills of the Oregon Coast Range near modern day Grand Ronde, Oregon, was a U.S. Army post established in March 1856 as part of a three fort system to guard the ...

  Citation × Citation Citation Abstract Copy Title: Foodways at Fort Yamhill, 1856-1866 : an archaeological and archival perspective Author: Eichelberger, Justin E. Fort Yamhill, located in the eastern foothills of the Oregon Coast Range near modern day Grand Ronde, Oregon, was a U.S. Army post established in March 1856 as part of a three fort system to guard the newly established Coast Reservation and to provide a Union presence in the state during the American Civil War. This thesis examines U.S. Army foodways at Fort Yamhill and provides a basis for future work on the subject. Combining the archaeological and archival data from the site provided the unique opportunity to examine the foodways of the mid-19th century U.S. Army holistically. Results of this research suggests that although the soldiers stationed at Fort Yamhill were at the end of long supply lines and far from populated cities, the diet consumed by the soldiers was adequate and often abundant. Procuring subsistence stores from many sources soldiers were able to procure a steady and healthful diet and often had the opportunity to display social and economic status through their patterns of food consumption. Title: Foodways at Fort Yamhill, 1856-1866 : an archaeological and archival perspective Author: Eichelberger, Justin E. Fort Yamhill, located in the eastern foothills of the Oregon Coast Range near modern day Grand Ronde, Oregon, was a U.S. Army post established in March 1856 as part of a three fort system to guard the newly established Coast Reservation and to provide a Union presence in the state during the American Civil War. This thesis examines U.S. Army foodways at Fort Yamhill and provides a basis for future work on the subject. Combining the archaeological and archival data from the site provided the unique opportunity to examine the foodways of the mid-19th century U.S. Army holistically. Results of this research suggests that although the soldiers stationed at Fort Yamhill were at the end of long supply lines and far from populated cities, the diet consumed by the soldiers was adequate and often abundant. Procuring subsistence stores from many sources soldiers were able to procure a steady and healthful diet and often had the opportunity to display social and economic status through their patterns of food consumption. Close

• 34. [Article] Spawning chinook salmon (Oncorhynchus tshawytscha) two years in a row : reconditioning for repeated gamete collection

  Spring chinook salmon, Oncorhynchus tshawytscha, in the Snake River Basin are listed as endangered under the Endangered Species Act. The typical life history of spring chinook salmon is semelparous. An ...

  Citation × Citation Citation Abstract Copy Title: Spawning chinook salmon (Oncorhynchus tshawytscha) two years in a row : reconditioning for repeated gamete collection Author: Mayer, Kent Corey Spring chinook salmon, Oncorhynchus tshawytscha, in the Snake River Basin are listed as endangered under the Endangered Species Act. The typical life history of spring chinook salmon is semelparous. An experiment was performed to see if mature male spring chinook salmon parr could be reconditioned after hand-spawning and spawned in successive years. The mature male parr were part of a 1997 and 1998 cohort of captive broodstock from the Grande Ronde River Basin in Oregon. Force-feeding was combined with volitional feeding in an attempt to inhibit senescence and increase survival time after spawning. The viscerosomatic index, fat and protein contents increased with survival time after spawning for both cohorts. There was a significant relationship between percent weight change and survival time for the 1997 cohort (p<0.001). Force-feeding had no effect on survival time after spawning for the 1997 cohort (p=0.074) or the 1998 cohort (p=0.178). Fat content, weight gain and survival time indicated that the reconditioning process was observable in the 1997 cohort at 77 days after spawning and was cyclical, resulting in a physiological response which allowed male chinook salmon to spawn in successive years. Fertilization trials with three reconditioned males yielded a fertilization success rate of 96.9% compared to 95.7% for 4-year old, anadromous male spring chinook salmon (p=0.152), measured as production of eyed-embryos. This experiment provides new knowledge of plasticity in the reproductive biology of male, stream-type, spring chinook salmon. Reconditioning and spawning male chinook salmon parr in successive years could be used to help maximize genetic diversity and aid in the recovery of endangered Oncorhynchus populations. Title: Spawning chinook salmon (Oncorhynchus tshawytscha) two years in a row : reconditioning for repeated gamete collection Author: Mayer, Kent Corey Spring chinook salmon, Oncorhynchus tshawytscha, in the Snake River Basin are listed as endangered under the Endangered Species Act. The typical life history of spring chinook salmon is semelparous. An experiment was performed to see if mature male spring chinook salmon parr could be reconditioned after hand-spawning and spawned in successive years. The mature male parr were part of a 1997 and 1998 cohort of captive broodstock from the Grande Ronde River Basin in Oregon. Force-feeding was combined with volitional feeding in an attempt to inhibit senescence and increase survival time after spawning. The viscerosomatic index, fat and protein contents increased with survival time after spawning for both cohorts. There was a significant relationship between percent weight change and survival time for the 1997 cohort (p<0.001). Force-feeding had no effect on survival time after spawning for the 1997 cohort (p=0.074) or the 1998 cohort (p=0.178). Fat content, weight gain and survival time indicated that the reconditioning process was observable in the 1997 cohort at 77 days after spawning and was cyclical, resulting in a physiological response which allowed male chinook salmon to spawn in successive years. Fertilization trials with three reconditioned males yielded a fertilization success rate of 96.9% compared to 95.7% for 4-year old, anadromous male spring chinook salmon (p=0.152), measured as production of eyed-embryos. This experiment provides new knowledge of plasticity in the reproductive biology of male, stream-type, spring chinook salmon. Reconditioning and spawning male chinook salmon parr in successive years could be used to help maximize genetic diversity and aid in the recovery of endangered Oncorhynchus populations. Close

• 35. [Article] The Oregon Tribal Archives Institute: Providing a Professional Development and Networking Opportunity for Oregon’s Tribal Communities

  Presenters: Natalia Fernández, Oregon State University; David Lewis, Confederated Tribes of the Grand Ronde Community of Oregon; and Jennifer O’Neal, University of Oregon. The session chair was Larry Landis, ...

  Citation × Citation Citation Abstract Copy Title: The Oregon Tribal Archives Institute: Providing a Professional Development and Networking Opportunity for Oregon’s Tribal Communities Author: Fernández, Natalia, O'Neal, Jennifer, Lewis, David Presenters: Natalia Fernández, Oregon State University; David Lewis, Confederated Tribes of the Grand Ronde Community of Oregon; and Jennifer O’Neal, University of Oregon. The session chair was Larry Landis, Oregon State University Title: The Oregon Tribal Archives Institute: Providing a Professional Development and Networking Opportunity for Oregon’s Tribal Communities Author: Fernández, Natalia, O'Neal, Jennifer, Lewis, David Presenters: Natalia Fernández, Oregon State University; David Lewis, Confederated Tribes of the Grand Ronde Community of Oregon; and Jennifer O’Neal, University of Oregon. The session chair was Larry Landis, Oregon State University Close

• 36. [Article] A resource survey of river energy and low-head hydroelectric power potential in Oregon

  The project was funded by the United States Department of Energy. Contract No. EG-77-S-07-1691 through the Idaho Water Resources Research Institute.

  Citation × Citation Citation Abstract Copy Title: A resource survey of river energy and low-head hydroelectric power potential in Oregon Author: Klingeman, Peter C., Oregon State University. Water Resources Research Institute, Idaho Water Resources Research Institute, State of Washington Water Research Center, Montana University Joint Water Resources Research Center The project was funded by the United States Department of Energy. Contract No. EG-77-S-07-1691 through the Idaho Water Resources Research Institute. Title: A resource survey of river energy and low-head hydroelectric power potential in Oregon Author: Klingeman, Peter C., Oregon State University. Water Resources Research Institute, Idaho Water Resources Research Institute, State of Washington Water Research Center, Montana University Joint Water Resources Research Center The project was funded by the United States Department of Energy. Contract No. EG-77-S-07-1691 through the Idaho Water Resources Research Institute. Close

• 37. [Article] An enthnobotanical analysis of basketry

  The focus of my thesis is ethnobotany which seeks to examine botanical resources and their context within particular cultures. My ethnographic research identifies and interprets the cultural processes ...

  Citation × Citation Citation Abstract Copy Title: An enthnobotanical analysis of basketry Author: Fluharty, Suzanne M. The focus of my thesis is ethnobotany which seeks to examine botanical resources and their context within particular cultures. My ethnographic research identifies and interprets the cultural processes woven into Oregon's coastal basketry through spirituality, environmental habitats, and utilized plant species. This is augmented with botanical research addressing the question of whether the basketry materials utilized by the diverse population of Pacific Northwest Tribes, can be identified to species through microscopic analysis. Comparative epidermal and cuticle techniques are tested for diagnostic potential in a pilot test of 19 species sampled from existing populations on Oregon's coast, from Tillamook Bay in the north to the Coquille River in the south. It builds on and seeks to integrate the knowledge of which native plant species have been historically utilized as fiber materials for baskets, mats, cordage and other woven articles by various Oregon and Northern California bands and tribes that are currently represented by the Coquille Indian Tribe, the Confederated Tribes of Grande Ronde, and the Confederated Tribes of Siletz. My research consists of three phases; 1) historic and ethnographic research, 2) standard taxonomic identification of targeted wetland species through collection of living plants, and 3) a comparative study of the cuticular surface of plants using scanning electron microscopy. My results confirm that epidermal and cuticular characteristics are diagnostic; however, the range of variability in the surface wax is extreme in the 19 selected wetland plants and can often be an impediment to the analysis of underlying characteristics. Furthermore, my results have a limited scope for the identification of basketry materials. The comparative process appears to be valuable in excluding known and identified botanical materials, but not in specifying which species is represented due to the range of possible and unknown species. With more comprehensive libraries of analyzed species, the gap between the eliminated species and the identified ones would narrow. Therefore, the identification of basketry materials to species is possible using the processes considered in this test pilot study but the number of analyzed species would need to be greatly expanded. Title: An enthnobotanical analysis of basketry Author: Fluharty, Suzanne M. The focus of my thesis is ethnobotany which seeks to examine botanical resources and their context within particular cultures. My ethnographic research identifies and interprets the cultural processes woven into Oregon's coastal basketry through spirituality, environmental habitats, and utilized plant species. This is augmented with botanical research addressing the question of whether the basketry materials utilized by the diverse population of Pacific Northwest Tribes, can be identified to species through microscopic analysis. Comparative epidermal and cuticle techniques are tested for diagnostic potential in a pilot test of 19 species sampled from existing populations on Oregon's coast, from Tillamook Bay in the north to the Coquille River in the south. It builds on and seeks to integrate the knowledge of which native plant species have been historically utilized as fiber materials for baskets, mats, cordage and other woven articles by various Oregon and Northern California bands and tribes that are currently represented by the Coquille Indian Tribe, the Confederated Tribes of Grande Ronde, and the Confederated Tribes of Siletz. My research consists of three phases; 1) historic and ethnographic research, 2) standard taxonomic identification of targeted wetland species through collection of living plants, and 3) a comparative study of the cuticular surface of plants using scanning electron microscopy. My results confirm that epidermal and cuticular characteristics are diagnostic; however, the range of variability in the surface wax is extreme in the 19 selected wetland plants and can often be an impediment to the analysis of underlying characteristics. Furthermore, my results have a limited scope for the identification of basketry materials. The comparative process appears to be valuable in excluding known and identified botanical materials, but not in specifying which species is represented due to the range of possible and unknown species. With more comprehensive libraries of analyzed species, the gap between the eliminated species and the identified ones would narrow. Therefore, the identification of basketry materials to species is possible using the processes considered in this test pilot study but the number of analyzed species would need to be greatly expanded. Close

• 38. [Article] Cable thinning in young forests with average DBH of 5-8 inches : a case study

  This paper describes the results of a time-study conducted near Grand Ronde, Oregon, to determine the production rates and total harvesting costs of a cable thinning in a young stand. The stand had a species ...

  Citation × Citation Citation Abstract Copy Title: Cable thinning in young forests with average DBH of 5-8 inches : a case study Author: Gabrielli, Robert Michael This paper describes the results of a time-study conducted near Grand Ronde, Oregon, to determine the production rates and total harvesting costs of a cable thinning in a young stand. The stand had a species mix of 48 percent western hemlock (Tsuga. heterophylla- (Raf.) Sarg.), 45 percent Douglas-fir (Pseudotsuga meuziesil (Mirb.) Franco), and 7 percent white fir (Abies concolor (Gord. & Fiend.) Lindi.). The stand had an average age of 33 years, with a mean dbh of the total stand (over 1.5 inches (3.8i cm) dbh) of 5.7 inches (14.48 cm). The mean dbh of the merchantable stems (over 6 inches (15.84 cm) dbh) was 8.3 inches. The yarder belonged to the small size class of yarders, and was rigged with a live skyline system using a selfclamping, manual slack-puliing carriage. Three hooking techniques consisting of three chokers with sliders, presetting three ring chokers andusing a toggle hook, and flying six ring chokers per turn were compared on a production basis. Regression equations were developed for the individual elements of the yarding cycles and for total cycle times ftr each hooking technique. Results indicate that there is no significant difference between the production rates of three chokers and sliders compared with three preset ring chokers and a toggle hook. There was a significant difierence between the production rates when using the three chokers and sliders compared with using six ring chokers and a toggle hook. The six ring chokers and toggle hook was about 13 percent faster per MBP. The total harvesting cost was compared with the mill value of the timber. The total harvesting cost included felling, limbing, and bucking cost, equipment move-in and move-out cost, yarding cost, loading cost, and hauling cost. Not included in the harvesting cost was road costs, engineering and layout costs, timber tax costs, or any profit and risk costs. The total harvesting cost came to $227.90 per MBP. The weighted average mill price for the logs was $250.24 per MBP. Title: Cable thinning in young forests with average DBH of 5-8 inches : a case study Author: Gabrielli, Robert Michael This paper describes the results of a time-study conducted near Grand Ronde, Oregon, to determine the production rates and total harvesting costs of a cable thinning in a young stand. The stand had a species mix of 48 percent western hemlock (Tsuga. heterophylla- (Raf.) Sarg.), 45 percent Douglas-fir (Pseudotsuga meuziesil (Mirb.) Franco), and 7 percent white fir (Abies concolor (Gord. & Fiend.) Lindi.). The stand had an average age of 33 years, with a mean dbh of the total stand (over 1.5 inches (3.8i cm) dbh) of 5.7 inches (14.48 cm). The mean dbh of the merchantable stems (over 6 inches (15.84 cm) dbh) was 8.3 inches. The yarder belonged to the small size class of yarders, and was rigged with a live skyline system using a selfclamping, manual slack-puliing carriage. Three hooking techniques consisting of three chokers with sliders, presetting three ring chokers andusing a toggle hook, and flying six ring chokers per turn were compared on a production basis. Regression equations were developed for the individual elements of the yarding cycles and for total cycle times ftr each hooking technique. Results indicate that there is no significant difference between the production rates of three chokers and sliders compared with three preset ring chokers and a toggle hook. There was a significant difierence between the production rates when using the three chokers and sliders compared with using six ring chokers and a toggle hook. The six ring chokers and toggle hook was about 13 percent faster per MBP. The total harvesting cost was compared with the mill value of the timber. The total harvesting cost included felling, limbing, and bucking cost, equipment move-in and move-out cost, yarding cost, loading cost, and hauling cost. Not included in the harvesting cost was road costs, engineering and layout costs, timber tax costs, or any profit and risk costs. The total harvesting cost came to $227.90 per MBP. The weighted average mill price for the logs was $250.24 per MBP. Close

• 39. [Article] Geology of the Elsie-lower Nehalem River area, south-central Clatsop and northern Tillamook counties, northwestern Oregon

  The middle Eocene Tillamook Volcanics form the oldest rock unit in the Elsie-lower Nehalem River area. K-Ar age determinations and age constraints imposed by foraminiferal and calcareous nannofossil assemblages ...

  Citation × Citation Citation Abstract Copy Title: Geology of the Elsie-lower Nehalem River area, south-central Clatsop and northern Tillamook counties, northwestern Oregon Author: Mumford, Daniel Franklin The middle Eocene Tillamook Volcanics form the oldest rock unit in the Elsie-lower Nehalem River area. K-Ar age determinations and age constraints imposed by foraminiferal and calcareous nannofossil assemblages of overlying sedimentary strata indicate an absolute age of about 42 Ma for the uppermost Tillamook Volcanics. Major oxide values indicate that the upper Tillamook Volcanics are highly fractionated high Fe-Ti tholeiitic basalts and basaltic andesites. These volcanics were erupted in a developing forearc under an extensional plate tectonic setting and formed a moderately large oceanic island. These subaerial flows are predominantly aphyric to plagioclase-augite porphyritic and have a pilotaxitic flow texture. Epochs of both normal and reverse magnetic polarity are recorded. Thermal subsidence related to the end of the volcanism resulted in deposition of the transgressive late Eocene Hamlet formation over the "Tillamook island". The informal Hamlet formation consists of three members. From oldest to youngest they are: the Roy Creek member, the Sunset Highway member, and the Sweet Home Creek member. Three lithofacies are present in the Roy Creek member. The stratigraphically lowest of these consists of basaltic boulder-pebble conglomerate and locally fossiliferous pebbly basaltic sandstones which were deposited in a high energy nearshore environment around rocky basaltic headlands and sea stacks of the Tillamook Volcanics. Molluscan fossils in this lithofacies are correlative to the middle to late Eocene "CowlitzCoaledo" fauna. Successively overlying lithofacies are a very coarseto coarse-grained shallow marine basaltic sandstone lithofacies and a medium- to fine-grained basaltic sandstone lithofacies. This fining upward sequenced documents progressive deepening of the depositional basin. Framework clasts in all three Roy Creek member lithofacies were predominantly derived from the Tillamook Volcanics. Pore-filling diagenetic chlorite, smectite (nontronite), calcite, and zeolite (clinoptilolite and heulandite) cements severely reduce the porosity of Roy Creek member sandstones. The Sunset Highway member of the Hamlet formation conformably overlies the Roy Creek member in eastern Clatsop and western Columbia counties and pinches out to the west at about the longitude of the Nehalem River in T. 4 N., R. 8 W.. The Sunset Highway member is predominantly composed of interbedded micaceous arkosic sandstone, lithic arkose, and muddy micaceous arkosic siltstone with a few beds of basaltic sandstone and basaltic debris flow breccias. The dominant micaceous arkosic composition of the Sunset Highway member reflects a distant extrabasinal granitic-metamorphic provenance and contrasts with that of the locally derived underlying basaltic Roy Creek member. Low angle trough cross-bedding, hummocky bedding, and microcross-laminations in fine to medium-grained arkosic sandstones are interpreted to have been produced by large storm-generated waves and on a high energy inner shelf. Thin interbeds of bioturbated mudstone and mollusc-bearing bioturbated sandstones formed during periods of fairweather conditions and during lower sedimentation rates. Rare matrix supported, basaltic debris-flow breccias and basaltic sandstones were derived from nearby basaltic headlands and by rivers draining the Tillamook Volcanics. Minor secondary intraparticle porosity occurs with some primary intergranular porosity in relatively matrix-free Sunset Highway member arkosic sandstones. However, much of the porosity and permeability of these potential sandstones has been reduced by diagenetic smectite coatings on framework grains and potassium feldspar overgrowths of feldspars. The mudstone-dominated Sweet Home Creek member was conformably deposited on the Sunset Highway member in eastern Clatsop and western Columbia counties. In western Clatsop County the Sweet Home Creek member directly and conformably overlies the Roy Creek member due to pinch out of the Sunset Highway member. Upper Narizian to lowermost Refugian benthic foraminiferal assemblages from this unit indicate outer shelf to upper slope sedimentation and continued subsidence of the depositional (Astoria) basin. Micromicaceous and carbonaceous silty mudatone dominates this unit but thin-bedded micaceous arkosic turbidite sandstones are present in the lower part, and rare, thin basaltic turbidites are present in the upper half. X-ray diffraction analysis shows that the dominant clay minerals in the Sweet Home Creek member niudstone are smectite (montmorillonite), kaolinite, and illite. The Cole Mountain basalt (informal) intrudes and locally overlies the Sweet Home Creek member. This caic-alkaline basaltic andesite is thought to have formed in a compressional plate tectonic regime and been emplaced on the outer shelf and upper slope as shallow irregular sills and dikes and minor submarine pillow basalt-hyaloclastite complexes. Siliceous nodules associated with pillowed units locally contains a few per cent pyrite and are associated with small areas of high-grade supergene copper-silver mineralization. The normally polarized Cole Mountain basalt is chemically, petrographically, and lithologically distinct from the Tillamook Volcanics and Grande Ronde Basalt of the Columbia River Basalt Group. The uppermost Narizian and Refugian (late Eocene) Jewell member of the Keasey Formation disconformably overlies the Cole Mountain basalt and Sweet Home Creek member. A thin basal glauconitic sandstone-siltstone reflects a period of reduced sedimentation under slightly reducing conditions and marks the disconformity. The unit primarily consists of laminated to thin bedded tuffaceous mudstone with a few thin tuff beds, small micaceous arkosic sandstone channels and clastic dikes. Clay minerals in the Jewell member are dominated by smectite (montmorillonite), with minor kaolinite and illite (degraded mica) in the lower part of the unit. Benthic foraminiferal assemblages in the unit indicate bathyal or slope depths and have been assigned to the lower Refugian to upper Narizian stages. In the middle Miocene, irregular dikes and sills of the Grande Ronde Basalt of the Columbia River Basalt Group intruded the late Eocene sedimentary strata in the thesis area. Two magneto-chemical types of Grande Ronde Basalt, N2/low MgO-low Ti02 and N2/ high MgO, were identified in the thesis area. These were geochemically and magnetically correlated to subaerial flows of magneto-chemical types IA and 5A of Mangan and others (1986) on the Columbia Plateau. The intrusions or invasive flows are interpreted to have been derived from voluminous plateau eruptions by invasion into soft, unconsolidated Neogene sediments at the marine/coast interface and then into the more brittle but ductile Paleogene strata of the area as first proposed by Beeson and others (1979). Uplift of the Coast Range was initiated in the late Miocene as a result of rapid offshore underthrusting in the subduction zone (Snavely and others, 1983). This has resulted in subaerial erosion and exposure of the faulted and gently folded forearc ridge and deposition of Quaternary alluvial gravels and sands along major rivers and creek in the thesis area. The dominant structural features of the Elsie-lower Nehalem River area are generally down-to-the-north, east-west-trending high angle faults with oblique offset and a conjugate set of oblique slip northwest-trending right-lateral and northeast-trending left-lateral faults. Folds are broad and relatively minor. The major east-west-trending fault pattern may have been initially produced by extensional stresses related to subsidence of the "Tillamook island". The conjugate strike-slip fault pattern may have been created by partial coupling of the forearc basin with oblique subduction of the Farallon plate. Other than timber, locally used rock aggregate from small quarries is the only resource that has been realized in the thesis area. Most quarries are developed in dikes and sills of Grande Ronde Basalt and the aggregate is used to macadamize logging roads. Diagenetic events have resulted in significant loss of porosity and permeability of potential reservoir sandstones in the area. The most favorable targets are relatively matrix-free micaceous arkosic sandstones in the Sunset Highway member, but these have been breached by erosion in the eastern part of the thesis area and pinch out in the western part of the area where potential mudstone cap rocks (e.g., Hamlet and Keasey formations) are present. Mudstones in the area contain woody-structured kerogen and average about 1% total organic carbon. These potential source rocks are generally thermally immature but have locally been baked by basaltic intrusions. This results in elevated vitrinite reflectance values (in the oil window and beyond) and, therefore, the mudstones may be potential source rocks for methane generation. Mineralized fault zones have substantial width and length but do not appear to carry anomalous concentrations of any metals other than arsenic. High-grade supergene copper-silver mineralization associated with Cole Mountain basalt intrusions has been documented but appears to be very localized and is not thought to be a viable exploration target. Title: Geology of the Elsie-lower Nehalem River area, south-central Clatsop and northern Tillamook counties, northwestern Oregon Author: Mumford, Daniel Franklin The middle Eocene Tillamook Volcanics form the oldest rock unit in the Elsie-lower Nehalem River area. K-Ar age determinations and age constraints imposed by foraminiferal and calcareous nannofossil assemblages of overlying sedimentary strata indicate an absolute age of about 42 Ma for the uppermost Tillamook Volcanics. Major oxide values indicate that the upper Tillamook Volcanics are highly fractionated high Fe-Ti tholeiitic basalts and basaltic andesites. These volcanics were erupted in a developing forearc under an extensional plate tectonic setting and formed a moderately large oceanic island. These subaerial flows are predominantly aphyric to plagioclase-augite porphyritic and have a pilotaxitic flow texture. Epochs of both normal and reverse magnetic polarity are recorded. Thermal subsidence related to the end of the volcanism resulted in deposition of the transgressive late Eocene Hamlet formation over the "Tillamook island". The informal Hamlet formation consists of three members. From oldest to youngest they are: the Roy Creek member, the Sunset Highway member, and the Sweet Home Creek member. Three lithofacies are present in the Roy Creek member. The stratigraphically lowest of these consists of basaltic boulder-pebble conglomerate and locally fossiliferous pebbly basaltic sandstones which were deposited in a high energy nearshore environment around rocky basaltic headlands and sea stacks of the Tillamook Volcanics. Molluscan fossils in this lithofacies are correlative to the middle to late Eocene "CowlitzCoaledo" fauna. Successively overlying lithofacies are a very coarseto coarse-grained shallow marine basaltic sandstone lithofacies and a medium- to fine-grained basaltic sandstone lithofacies. This fining upward sequenced documents progressive deepening of the depositional basin. Framework clasts in all three Roy Creek member lithofacies were predominantly derived from the Tillamook Volcanics. Pore-filling diagenetic chlorite, smectite (nontronite), calcite, and zeolite (clinoptilolite and heulandite) cements severely reduce the porosity of Roy Creek member sandstones. The Sunset Highway member of the Hamlet formation conformably overlies the Roy Creek member in eastern Clatsop and western Columbia counties and pinches out to the west at about the longitude of the Nehalem River in T. 4 N., R. 8 W.. The Sunset Highway member is predominantly composed of interbedded micaceous arkosic sandstone, lithic arkose, and muddy micaceous arkosic siltstone with a few beds of basaltic sandstone and basaltic debris flow breccias. The dominant micaceous arkosic composition of the Sunset Highway member reflects a distant extrabasinal granitic-metamorphic provenance and contrasts with that of the locally derived underlying basaltic Roy Creek member. Low angle trough cross-bedding, hummocky bedding, and microcross-laminations in fine to medium-grained arkosic sandstones are interpreted to have been produced by large storm-generated waves and on a high energy inner shelf. Thin interbeds of bioturbated mudstone and mollusc-bearing bioturbated sandstones formed during periods of fairweather conditions and during lower sedimentation rates. Rare matrix supported, basaltic debris-flow breccias and basaltic sandstones were derived from nearby basaltic headlands and by rivers draining the Tillamook Volcanics. Minor secondary intraparticle porosity occurs with some primary intergranular porosity in relatively matrix-free Sunset Highway member arkosic sandstones. However, much of the porosity and permeability of these potential sandstones has been reduced by diagenetic smectite coatings on framework grains and potassium feldspar overgrowths of feldspars. The mudstone-dominated Sweet Home Creek member was conformably deposited on the Sunset Highway member in eastern Clatsop and western Columbia counties. In western Clatsop County the Sweet Home Creek member directly and conformably overlies the Roy Creek member due to pinch out of the Sunset Highway member. Upper Narizian to lowermost Refugian benthic foraminiferal assemblages from this unit indicate outer shelf to upper slope sedimentation and continued subsidence of the depositional (Astoria) basin. Micromicaceous and carbonaceous silty mudatone dominates this unit but thin-bedded micaceous arkosic turbidite sandstones are present in the lower part, and rare, thin basaltic turbidites are present in the upper half. X-ray diffraction analysis shows that the dominant clay minerals in the Sweet Home Creek member niudstone are smectite (montmorillonite), kaolinite, and illite. The Cole Mountain basalt (informal) intrudes and locally overlies the Sweet Home Creek member. This caic-alkaline basaltic andesite is thought to have formed in a compressional plate tectonic regime and been emplaced on the outer shelf and upper slope as shallow irregular sills and dikes and minor submarine pillow basalt-hyaloclastite complexes. Siliceous nodules associated with pillowed units locally contains a few per cent pyrite and are associated with small areas of high-grade supergene copper-silver mineralization. The normally polarized Cole Mountain basalt is chemically, petrographically, and lithologically distinct from the Tillamook Volcanics and Grande Ronde Basalt of the Columbia River Basalt Group. The uppermost Narizian and Refugian (late Eocene) Jewell member of the Keasey Formation disconformably overlies the Cole Mountain basalt and Sweet Home Creek member. A thin basal glauconitic sandstone-siltstone reflects a period of reduced sedimentation under slightly reducing conditions and marks the disconformity. The unit primarily consists of laminated to thin bedded tuffaceous mudstone with a few thin tuff beds, small micaceous arkosic sandstone channels and clastic dikes. Clay minerals in the Jewell member are dominated by smectite (montmorillonite), with minor kaolinite and illite (degraded mica) in the lower part of the unit. Benthic foraminiferal assemblages in the unit indicate bathyal or slope depths and have been assigned to the lower Refugian to upper Narizian stages. In the middle Miocene, irregular dikes and sills of the Grande Ronde Basalt of the Columbia River Basalt Group intruded the late Eocene sedimentary strata in the thesis area. Two magneto-chemical types of Grande Ronde Basalt, N2/low MgO-low Ti02 and N2/ high MgO, were identified in the thesis area. These were geochemically and magnetically correlated to subaerial flows of magneto-chemical types IA and 5A of Mangan and others (1986) on the Columbia Plateau. The intrusions or invasive flows are interpreted to have been derived from voluminous plateau eruptions by invasion into soft, unconsolidated Neogene sediments at the marine/coast interface and then into the more brittle but ductile Paleogene strata of the area as first proposed by Beeson and others (1979). Uplift of the Coast Range was initiated in the late Miocene as a result of rapid offshore underthrusting in the subduction zone (Snavely and others, 1983). This has resulted in subaerial erosion and exposure of the faulted and gently folded forearc ridge and deposition of Quaternary alluvial gravels and sands along major rivers and creek in the thesis area. The dominant structural features of the Elsie-lower Nehalem River area are generally down-to-the-north, east-west-trending high angle faults with oblique offset and a conjugate set of oblique slip northwest-trending right-lateral and northeast-trending left-lateral faults. Folds are broad and relatively minor. The major east-west-trending fault pattern may have been initially produced by extensional stresses related to subsidence of the "Tillamook island". The conjugate strike-slip fault pattern may have been created by partial coupling of the forearc basin with oblique subduction of the Farallon plate. Other than timber, locally used rock aggregate from small quarries is the only resource that has been realized in the thesis area. Most quarries are developed in dikes and sills of Grande Ronde Basalt and the aggregate is used to macadamize logging roads. Diagenetic events have resulted in significant loss of porosity and permeability of potential reservoir sandstones in the area. The most favorable targets are relatively matrix-free micaceous arkosic sandstones in the Sunset Highway member, but these have been breached by erosion in the eastern part of the thesis area and pinch out in the western part of the area where potential mudstone cap rocks (e.g., Hamlet and Keasey formations) are present. Mudstones in the area contain woody-structured kerogen and average about 1% total organic carbon. These potential source rocks are generally thermally immature but have locally been baked by basaltic intrusions. This results in elevated vitrinite reflectance values (in the oil window and beyond) and, therefore, the mudstones may be potential source rocks for methane generation. Mineralized fault zones have substantial width and length but do not appear to carry anomalous concentrations of any metals other than arsenic. High-grade supergene copper-silver mineralization associated with Cole Mountain basalt intrusions has been documented but appears to be very localized and is not thought to be a viable exploration target. Close

• 40. [Article] Geology of the Buster Creek-Nehalem Valley area, Clatsop County, northwest Oregon

  Six Tertiary rock units are exposed in the Buster Creek-Nehalem Valley area. They are, from oldest to youngest: upper Eocene Tillamook Volcanics; upper Eocene Cowlitz Formation; upper Eocene Keasey Formation; ...

  Citation × Citation Citation Abstract Copy Title: Geology of the Buster Creek-Nehalem Valley area, Clatsop County, northwest Oregon Author: Olbinski, James Steven Six Tertiary rock units are exposed in the Buster Creek-Nehalem Valley area. They are, from oldest to youngest: upper Eocene Tillamook Volcanics; upper Eocene Cowlitz Formation; upper Eocene Keasey Formation; upper Eocene Vesper Church formation (informal); upper Eocene to Oligocene Pittsburg Bluff Formation; and middle Miocene Depoe Bay Basalt. The Tillamook Volcanics is composed of basaltic andesite subaerial flows (SiO2 54.19% to 55.67%) and volcanic debris flows. The platy jointed subaerial flows are generally porphyritic with a pilotaxitic groundmass; a few aphyric flows with well defined flow banding are present. Highly vesicular flow tops typically show alteration of ilmenite to leucoxene producing a diagnostic bleached white appearance. Debris flows are comprised of very poorly sorted, angular, volcanic and minor sedimentary rock clasts in a mud matrix. Commonly this lithology is intruded by porphyritic and vesicular dikes. Major oxides of the Tillamook basaltic andesites suggest that these volcanic rocks may have erupted in an oceanic island "spreading center" environment. The Cowlitz Formation unconformably overlies the Tillamook Volcanics in the study area. This formation is divided into five informal members: a basal basaltic andesite conglomerate; a unit of interbedded micaceous arkese, volcanic lithic arenite and mudstone; a thick structureless mudstone; rhythmically laminated turbidite sandstone and siltstone; and a thick upper arkosic sandstone. The basal conglomerate represents a fluvial braided stream to high energy marine shoreline environment. The finer grained middle members indicate a deepening up sequence. The upper sandstone member is a micaceous, well-sorted, hummocky bedded, porous, very friable sandstone deposited in a high energy storm-dominated shelf to nearshore environment. The upper sandstone member of the Cowlitz Formation ("Clark and Wilson sand" of the Mist gas field) is the current target of active drilling in adjacent areas by several petroleum companies. This upper sandstone and lower arkosic sandstones represent favorable targets in contact with organic-rich, but immature, source rocks in potential fault bounded structural highs and erosional pinchouts in the northern part of the study area. The Narizian to Refugian Keasey Formation is represented by the Jewell member (informal), in the study area. The Jewell member, a well-bedded to laminated, tuffaceous, indurated mudstone, unconformably overlies the more extensively faulted Cowlitz Formation. Upper slope water depths of 200-600 m are indicated by foraminiferal and molluscan assemblages. A lithologically distinct and mappable turbidite unit crops out in the study area and is informally named in this thesis the Vesper Church formation. The Vesper Church formation represents west- to northwest-trending turbidite-filled "sea gullies" deposited at bathyal depths (1,000-1,500 m) on the lower slope. Thin-bedded channelized turbidites with Bouma c, d and e sequences and local thick amalgamated sandstones characterize this unit. The upper Eocene (Refugian) Pittsburg Bluff Formation conformably overlies the Vesper Church formation. Molluscan assemblages from the basal part of this formation indicate water depths of 20-200 m; thus, a significant shallowing episode between the Vesper Church and Pittsburg Bluff formations is indicated. Thick, bioturbated, glauconitic to fine-grained tuffaceous sandstone and sandy mudstone suggest an inner to middle (possibly outer) continental shelf depositional environment for the Pittsburg Bluff strata. Following a period of high-angle northeast trending faulting, two middle Miocene Depoe Bay Basalt dikes intruded the sedimentary formations exposed in the area. The reversely polarized Northrup Creek dike can be traced over 8.5 km and has a paleomagnetic declination of 170° and a steep inclination of -74°, possibly a result of secular variation of the geomagnetic pole during cooling of the dike through its Cuire temperature (Nelson, 1983). These aphanitic to sparsely micro-porhyritic tholeiitic basalts are chemically identical to the Grande Ronde Basalt of the Columbia Plateau. A recent hypothesis by Beeson et al. (1979) suggests that all Miocene coastal basalts represent the distal ends of subaerial Columbia River basalts which reached the Miocene shoreline and intruded or "invaded" soft marine sediments. The reversed stratigraphic order of high and low MgO Depoe Bay (Grande Ronde) basaltic sills intruding Keasey and Cowlitz strata, as much as 1600 m below the surface in the petroleum exploration well Quintan_a Watzek 30-1 Watzek 30-1 in this study area, illustrates a complicating factor in the emplacement mechanism if these are "invasive" intrusions. In late middle Miocene the northern Oregon Coast Range anticline was formed, possibly in response to a period of underthrusting (Snavely et al., 1980b). Contemporaneously, a second set of left-lateral and right-lateral conjugate faults (N55°E and N55°W) cut the middle Miocene basalt dikes. This faulting may be related to north-south compression and clockwise rotation of western Oregon and southwest Washington associated with the oblique subduction of the Juan De Fuca Plate beneath the North American Plate as suggested by Magill et al. (1981) and Coe and Wells (1982). Title: Geology of the Buster Creek-Nehalem Valley area, Clatsop County, northwest Oregon Author: Olbinski, James Steven Six Tertiary rock units are exposed in the Buster Creek-Nehalem Valley area. They are, from oldest to youngest: upper Eocene Tillamook Volcanics; upper Eocene Cowlitz Formation; upper Eocene Keasey Formation; upper Eocene Vesper Church formation (informal); upper Eocene to Oligocene Pittsburg Bluff Formation; and middle Miocene Depoe Bay Basalt. The Tillamook Volcanics is composed of basaltic andesite subaerial flows (SiO2 54.19% to 55.67%) and volcanic debris flows. The platy jointed subaerial flows are generally porphyritic with a pilotaxitic groundmass; a few aphyric flows with well defined flow banding are present. Highly vesicular flow tops typically show alteration of ilmenite to leucoxene producing a diagnostic bleached white appearance. Debris flows are comprised of very poorly sorted, angular, volcanic and minor sedimentary rock clasts in a mud matrix. Commonly this lithology is intruded by porphyritic and vesicular dikes. Major oxides of the Tillamook basaltic andesites suggest that these volcanic rocks may have erupted in an oceanic island "spreading center" environment. The Cowlitz Formation unconformably overlies the Tillamook Volcanics in the study area. This formation is divided into five informal members: a basal basaltic andesite conglomerate; a unit of interbedded micaceous arkese, volcanic lithic arenite and mudstone; a thick structureless mudstone; rhythmically laminated turbidite sandstone and siltstone; and a thick upper arkosic sandstone. The basal conglomerate represents a fluvial braided stream to high energy marine shoreline environment. The finer grained middle members indicate a deepening up sequence. The upper sandstone member is a micaceous, well-sorted, hummocky bedded, porous, very friable sandstone deposited in a high energy storm-dominated shelf to nearshore environment. The upper sandstone member of the Cowlitz Formation ("Clark and Wilson sand" of the Mist gas field) is the current target of active drilling in adjacent areas by several petroleum companies. This upper sandstone and lower arkosic sandstones represent favorable targets in contact with organic-rich, but immature, source rocks in potential fault bounded structural highs and erosional pinchouts in the northern part of the study area. The Narizian to Refugian Keasey Formation is represented by the Jewell member (informal), in the study area. The Jewell member, a well-bedded to laminated, tuffaceous, indurated mudstone, unconformably overlies the more extensively faulted Cowlitz Formation. Upper slope water depths of 200-600 m are indicated by foraminiferal and molluscan assemblages. A lithologically distinct and mappable turbidite unit crops out in the study area and is informally named in this thesis the Vesper Church formation. The Vesper Church formation represents west- to northwest-trending turbidite-filled "sea gullies" deposited at bathyal depths (1,000-1,500 m) on the lower slope. Thin-bedded channelized turbidites with Bouma c, d and e sequences and local thick amalgamated sandstones characterize this unit. The upper Eocene (Refugian) Pittsburg Bluff Formation conformably overlies the Vesper Church formation. Molluscan assemblages from the basal part of this formation indicate water depths of 20-200 m; thus, a significant shallowing episode between the Vesper Church and Pittsburg Bluff formations is indicated. Thick, bioturbated, glauconitic to fine-grained tuffaceous sandstone and sandy mudstone suggest an inner to middle (possibly outer) continental shelf depositional environment for the Pittsburg Bluff strata. Following a period of high-angle northeast trending faulting, two middle Miocene Depoe Bay Basalt dikes intruded the sedimentary formations exposed in the area. The reversely polarized Northrup Creek dike can be traced over 8.5 km and has a paleomagnetic declination of 170° and a steep inclination of -74°, possibly a result of secular variation of the geomagnetic pole during cooling of the dike through its Cuire temperature (Nelson, 1983). These aphanitic to sparsely micro-porhyritic tholeiitic basalts are chemically identical to the Grande Ronde Basalt of the Columbia Plateau. A recent hypothesis by Beeson et al. (1979) suggests that all Miocene coastal basalts represent the distal ends of subaerial Columbia River basalts which reached the Miocene shoreline and intruded or "invaded" soft marine sediments. The reversed stratigraphic order of high and low MgO Depoe Bay (Grande Ronde) basaltic sills intruding Keasey and Cowlitz strata, as much as 1600 m below the surface in the petroleum exploration well Quintan_a Watzek 30-1 Watzek 30-1 in this study area, illustrates a complicating factor in the emplacement mechanism if these are "invasive" intrusions. In late middle Miocene the northern Oregon Coast Range anticline was formed, possibly in response to a period of underthrusting (Snavely et al., 1980b). Contemporaneously, a second set of left-lateral and right-lateral conjugate faults (N55°E and N55°W) cut the middle Miocene basalt dikes. This faulting may be related to north-south compression and clockwise rotation of western Oregon and southwest Washington associated with the oblique subduction of the Juan De Fuca Plate beneath the North American Plate as suggested by Magill et al. (1981) and Coe and Wells (1982). Close