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• 11. [Article] Stratigraphy, structure, and natural gas potential of tertiary sedimentary and volcanic units, Clatskanie 7.5 minute quadrangle, Northwest Oregon

  The geology and natural gas potential of the Clatskanie 7.5-minute quadrangle in Columbia County, Oregon was studied utilizing a combination of geologic mapping, measuring of stratigraphic sections, diatom ...

  Citation × Citation Citation Abstract Copy Title: Stratigraphy, structure, and natural gas potential of tertiary sedimentary and volcanic units, Clatskanie 7.5 minute quadrangle, Northwest Oregon Author: Eriksson, Andrew The geology and natural gas potential of the Clatskanie 7.5-minute quadrangle in Columbia County, Oregon was studied utilizing a combination of geologic mapping, measuring of stratigraphic sections, diatom and molluscan fossil identifications, with subsurface geophysical data and petrographic and geochemical analyses. The stratigraphy of the study area consists of two Tertiary volcanic units (Grays River Volcanics and Columbia River Basalt Group) and four sedimentary units (Cowlitz (subsurface) Keasey, Pittsburg Bluff, and Scappoose formations) that were deposited in the Nehalem forearc basin. The major structure of the area is defined by the oblique-slip Scappoose-Clatskanie fault with both normal and dextral motion. In the east-central part of the study area, this post-Miocene fault zone, formed by a right step over in a right-lateral strike-slip system, created an extensional zone with abundant normal faulting (horsts and grabens). The faulting uplifted an isolated block of middle Eocene Grays River Volcanics subaerial flows against downdropped Miocene Columbia River Basalt in the northwestern part of the map area near the town of Clatskanie along Highway 30. This block was part of a major Grays River Volcanics paleohigh (herein named the Clatskanie High) and forms part of a regional gravity/magnetic high beneath the Columbia river. The Clatskanie High and the Windy Ridge High (subsurfance paleohigh also composed of Grays River Volcanics) in the central to southern part of the study area, restricted deposition and caused onlapping of the Cowlitz, Keasey, and Pittsburg Bluff formations. The Clatskanie High shield volcano defines the northern boundary of the Mist Gas Field. In addition, local unconformities at the base of the Keasey and Pittsburg Bluff formations progressively truncate the Cowlitz C&W sandstone reservoir and upper mudstone seal to the north. The largely unexplored central and northeastern parts of the study area near the Scappoose-Clatskanie fault zone with horst and grabens and stratigraphic pinchouts represent some of the most promising untested exploration plays in the quadrangle. Associated wtih the Clatskanie High are two new (informal) members of the Oligocene Pittsburg Bluff Formation that are defined and mapped by this study. The Conyers Creek member (informal) is a shallow-marine mollusk-bearing pebbly-basaltic litharenite (a poorly sorted nearshore to shoreface sandstone) with an interbedded fossiliferous fine pebble conglomerate of Grays River volcanic clasts. The lens-like nearshore unit was deposited on the margins of the uplifted Grays River basaltic oceanic island and, thus, restricted to an area around the paleohigh. Locally overlying the Conyers Creek member and interbedded with the East Fork member (Pittsburg Bluff Formation) is the Clatskanie Conglomerate member (the second informal member defined by this study). The 180 feet (55 meter) thick member consists of a basal, clast-supported 110 feet (33 meter) thick polymict conglomerate and upper well-consolidated 70 feet (21 meter) think micaceous arkosic sandstone. The Clatskanie Conglomerate is a lens-like fluvial deposit in the northwestern part of the study area, possibly syndepositional and restricted in deposition to the center of a growing syncline. The cobble to boulder sized clasts of quartzite, chert, metamorphics, and andesites/dacites indicate extrabasinal sources such as the Western Cascades arc and continental sources in eastern Oregon, Idaho, Montana, and eastern Washington via an ancestral Columbia River drainage system. The diatom-bearing tuffaceous clayey siltstone of the Keasey Formation and the mollusk-bearing sandy siltstone of the East Fork member (Pittsburg Bluff Formation) formed in continental slope and middle to outer shelf environments. Extensive explosive dacitic eruptions in the nearby Western Cascade arc contributed abundant ash, which washed into the forearc basin. Local Thyosira chemosynthetic pelecypods and calcareous concretionary beds indicate the local presence of either cold methane seeps or a gas hydrate system on the Pittsburg Bluff continental shelf. The Scappoose Formation consists predominantly of a basal basalt and siltstone rip-up conglomerate deposited in an incised valley during a low stand systems tract (LST). The conglomerate is overlain by a diatom-bearing shallow-marine tuffaceous siltstone of a transgressive and highstand systems tracts (TST & HST), and capped by a cross-bedded fluvial lithic arkosic sandstone of a second lowstand systems tract (LST). Chemical analysis of the basal basalt conglomerate clasts indicate that they were derived from erosion of high TiO2R2 Wapshilla Ridge flow unit of the Grande Ronde Basalt (16.5 to 15.6 Ma) of the lower to middle Miocene Columbia River Basalt Group. The Scappoose Formation also includes thin fluvial and lacustrine sandstones and tuffs interbedded with Columbia River Basalt flows. Capping these Tertiary units are three units of low-MgO Grande Ronde Basalt of the Columbia River Basalt Group. These include 1-2 basal aphyric flow(s) of the high-TiO2R2 Wapshilla Ridge flow unit, at least six flows (some invasive) of the R2 low-TiO2 Grouse Creek flow unit, and the upper sparsely glomerophyric flows of N2 Winter Water flow unit. The structural history of the region is characterized by two major tectonic events. A late Eocene extensional period prior to deposition of the Keasey Formation created normal faulting (horsts and grabens) throughout the Cowlitz Formation. These faults formed most of the structural traps in the Mist Gas Field including those drilled by producing wells in the southern part of the quadrangle near the Windy Ridge High. The post-Miocene episode was dominated by wrench fault tectonics that manifested as strike-slip oblique-slip motion on dominant northwest-trending and subordinate northeast-trending faults in the Columbia River Basalt Group flows. Title: Stratigraphy, structure, and natural gas potential of tertiary sedimentary and volcanic units, Clatskanie 7.5 minute quadrangle, Northwest Oregon Author: Eriksson, Andrew The geology and natural gas potential of the Clatskanie 7.5-minute quadrangle in Columbia County, Oregon was studied utilizing a combination of geologic mapping, measuring of stratigraphic sections, diatom and molluscan fossil identifications, with subsurface geophysical data and petrographic and geochemical analyses. The stratigraphy of the study area consists of two Tertiary volcanic units (Grays River Volcanics and Columbia River Basalt Group) and four sedimentary units (Cowlitz (subsurface) Keasey, Pittsburg Bluff, and Scappoose formations) that were deposited in the Nehalem forearc basin. The major structure of the area is defined by the oblique-slip Scappoose-Clatskanie fault with both normal and dextral motion. In the east-central part of the study area, this post-Miocene fault zone, formed by a right step over in a right-lateral strike-slip system, created an extensional zone with abundant normal faulting (horsts and grabens). The faulting uplifted an isolated block of middle Eocene Grays River Volcanics subaerial flows against downdropped Miocene Columbia River Basalt in the northwestern part of the map area near the town of Clatskanie along Highway 30. This block was part of a major Grays River Volcanics paleohigh (herein named the Clatskanie High) and forms part of a regional gravity/magnetic high beneath the Columbia river. The Clatskanie High and the Windy Ridge High (subsurfance paleohigh also composed of Grays River Volcanics) in the central to southern part of the study area, restricted deposition and caused onlapping of the Cowlitz, Keasey, and Pittsburg Bluff formations. The Clatskanie High shield volcano defines the northern boundary of the Mist Gas Field. In addition, local unconformities at the base of the Keasey and Pittsburg Bluff formations progressively truncate the Cowlitz C&W sandstone reservoir and upper mudstone seal to the north. The largely unexplored central and northeastern parts of the study area near the Scappoose-Clatskanie fault zone with horst and grabens and stratigraphic pinchouts represent some of the most promising untested exploration plays in the quadrangle. Associated wtih the Clatskanie High are two new (informal) members of the Oligocene Pittsburg Bluff Formation that are defined and mapped by this study. The Conyers Creek member (informal) is a shallow-marine mollusk-bearing pebbly-basaltic litharenite (a poorly sorted nearshore to shoreface sandstone) with an interbedded fossiliferous fine pebble conglomerate of Grays River volcanic clasts. The lens-like nearshore unit was deposited on the margins of the uplifted Grays River basaltic oceanic island and, thus, restricted to an area around the paleohigh. Locally overlying the Conyers Creek member and interbedded with the East Fork member (Pittsburg Bluff Formation) is the Clatskanie Conglomerate member (the second informal member defined by this study). The 180 feet (55 meter) thick member consists of a basal, clast-supported 110 feet (33 meter) thick polymict conglomerate and upper well-consolidated 70 feet (21 meter) think micaceous arkosic sandstone. The Clatskanie Conglomerate is a lens-like fluvial deposit in the northwestern part of the study area, possibly syndepositional and restricted in deposition to the center of a growing syncline. The cobble to boulder sized clasts of quartzite, chert, metamorphics, and andesites/dacites indicate extrabasinal sources such as the Western Cascades arc and continental sources in eastern Oregon, Idaho, Montana, and eastern Washington via an ancestral Columbia River drainage system. The diatom-bearing tuffaceous clayey siltstone of the Keasey Formation and the mollusk-bearing sandy siltstone of the East Fork member (Pittsburg Bluff Formation) formed in continental slope and middle to outer shelf environments. Extensive explosive dacitic eruptions in the nearby Western Cascade arc contributed abundant ash, which washed into the forearc basin. Local Thyosira chemosynthetic pelecypods and calcareous concretionary beds indicate the local presence of either cold methane seeps or a gas hydrate system on the Pittsburg Bluff continental shelf. The Scappoose Formation consists predominantly of a basal basalt and siltstone rip-up conglomerate deposited in an incised valley during a low stand systems tract (LST). The conglomerate is overlain by a diatom-bearing shallow-marine tuffaceous siltstone of a transgressive and highstand systems tracts (TST & HST), and capped by a cross-bedded fluvial lithic arkosic sandstone of a second lowstand systems tract (LST). Chemical analysis of the basal basalt conglomerate clasts indicate that they were derived from erosion of high TiO2R2 Wapshilla Ridge flow unit of the Grande Ronde Basalt (16.5 to 15.6 Ma) of the lower to middle Miocene Columbia River Basalt Group. The Scappoose Formation also includes thin fluvial and lacustrine sandstones and tuffs interbedded with Columbia River Basalt flows. Capping these Tertiary units are three units of low-MgO Grande Ronde Basalt of the Columbia River Basalt Group. These include 1-2 basal aphyric flow(s) of the high-TiO2R2 Wapshilla Ridge flow unit, at least six flows (some invasive) of the R2 low-TiO2 Grouse Creek flow unit, and the upper sparsely glomerophyric flows of N2 Winter Water flow unit. The structural history of the region is characterized by two major tectonic events. A late Eocene extensional period prior to deposition of the Keasey Formation created normal faulting (horsts and grabens) throughout the Cowlitz Formation. These faults formed most of the structural traps in the Mist Gas Field including those drilled by producing wells in the southern part of the quadrangle near the Windy Ridge High. The post-Miocene episode was dominated by wrench fault tectonics that manifested as strike-slip oblique-slip motion on dominant northwest-trending and subordinate northeast-trending faults in the Columbia River Basalt Group flows. 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• 12. [Article] A spatially explicit model for allocating conservation efforts : the Grand Ronde River basin, Oregon

  The spatial and dynamic pattern of landscape changes has a profound effect on the supply of environmental services, including the provision of habitat for fish and wildlife. Spatial heterogeneity is a ...

  Citation × Citation Citation Abstract Copy Title: A spatially explicit model for allocating conservation efforts : the Grand Ronde River basin, Oregon Author: Watanabe, Michio The spatial and dynamic pattern of landscape changes has a profound effect on the supply of environmental services, including the provision of habitat for fish and wildlife. Spatial heterogeneity is a common feature of landscapes in the Pacific Northwest, most notably in areas important to the production of salmonid fish species. This heterogeneity complicates attempts to design and implement policies to conserve the stocks of such species. To date, millions of dollars have been spent to improve habitat for salmonids, with mixed success. This research examines the spatial implications of habitat restoration activities for the benefit of endangered salmonid fish species. A theoretical model defining an economically efficient allocation of restoration practices is developed for a hypothetical stream with a range of hydrological and spatial characteristics. An integrated hydrological, biological and economic modeling approach is then developed, and an empirical analysis is applied to the upper Grande Ronde River basin in northeastern Oregon. Results of these analyses indicate that the heterogeneous nature of riparian conditions and stream morphology has a substantial effect on the efficacy of restoration activities. The minimum cost allocation of restoration activities for small temperature reductions is to apply restoration efforts to nearby upstream reaches, while cumulative effects become important as the magnitude of desired temperature reduction increases. However, as the magnitude of desired temperature reductions increases, temperature reduction per dollar of restoration efforts decreases rapidly. In terms of specific riparian restoration efforts, passive restoration is preferred to active restoration as the magnitude of desired temperature reductions decreases and / or as the time frame considered is increased. It is also less costly in general to implement restoration activities in tributaries if the objective is to maximize stream length where water temperatures decrease by a specific amount. When two targeting options are compared (a fish abundance goal vs. a temperature reduction goal), this study found that temperature targeting is inefficient in the sense that it is possible to produce a larger salmonid population with the same budget, and that the levels of temperature targets have significant impacts on fishery benefits. Title: A spatially explicit model for allocating conservation efforts : the Grand Ronde River basin, Oregon Author: Watanabe, Michio The spatial and dynamic pattern of landscape changes has a profound effect on the supply of environmental services, including the provision of habitat for fish and wildlife. Spatial heterogeneity is a common feature of landscapes in the Pacific Northwest, most notably in areas important to the production of salmonid fish species. This heterogeneity complicates attempts to design and implement policies to conserve the stocks of such species. To date, millions of dollars have been spent to improve habitat for salmonids, with mixed success. This research examines the spatial implications of habitat restoration activities for the benefit of endangered salmonid fish species. A theoretical model defining an economically efficient allocation of restoration practices is developed for a hypothetical stream with a range of hydrological and spatial characteristics. An integrated hydrological, biological and economic modeling approach is then developed, and an empirical analysis is applied to the upper Grande Ronde River basin in northeastern Oregon. Results of these analyses indicate that the heterogeneous nature of riparian conditions and stream morphology has a substantial effect on the efficacy of restoration activities. The minimum cost allocation of restoration activities for small temperature reductions is to apply restoration efforts to nearby upstream reaches, while cumulative effects become important as the magnitude of desired temperature reduction increases. However, as the magnitude of desired temperature reductions increases, temperature reduction per dollar of restoration efforts decreases rapidly. In terms of specific riparian restoration efforts, passive restoration is preferred to active restoration as the magnitude of desired temperature reductions decreases and / or as the time frame considered is increased. It is also less costly in general to implement restoration activities in tributaries if the objective is to maximize stream length where water temperatures decrease by a specific amount. When two targeting options are compared (a fish abundance goal vs. a temperature reduction goal), this study found that temperature targeting is inefficient in the sense that it is possible to produce a larger salmonid population with the same budget, and that the levels of temperature targets have significant impacts on fishery benefits. Close

• 13. [Article] Feeder dikes to the Columbia River flood basalts : underpinnings of a large igneous province

  Feeder dikes to the Columbia River Basalt Group (CRBG) large igneous province provide a rare opportunity to examine magma transport through the shallow crust during flood basalt eruptions. Over 70% of ...

  Citation × Citation Citation Abstract Copy Title: Feeder dikes to the Columbia River flood basalts : underpinnings of a large igneous province Author: Petcovic, Heather L. Feeder dikes to the Columbia River Basalt Group (CRBG) large igneous province provide a rare opportunity to examine magma transport through the shallow crust during flood basalt eruptions. Over 70% of the CRBG erupted from the Chief Joseph dike swarm, which is exposed across southeastern Washington, eastern Oregon, and western Idaho. The four manuscripts of this dissertation examine physical, thermal, and compositional characteristics of dikes from the southern Chief Joseph swarm. The majority of CRBG dikes are chilled against their wallrock, however, rare dikes have induced partial melting in their wallrock. Melt zones in tonalite wallrock adjacent to the Maxwell Lake dike are up to 4 in thick and contain up to 47 volume percent quenched silicic melt produced from dehydration-melting reactions involvir biotite, hornblende, quartz, orthoclase, and plagioclase. Melt zones record the thermal history of basalt flow and cooling in the Maxwell Lake dike, a feeder to Wapshilla Ridge flows (Grande Ronde Basalt). Results of one- and two-dimensional numerical modeling suggest that basalt flowed in the Maxwell Lake dike for 3-4 years, yielding maximum eruption rates of 3.4-4.6 km3/day for typical Wapshilla Ridge flows. The Maxwell Lake dike likely represents an upper crustal exposure of a long-lived point source in the CRBG. Chief Joseph dikes are concentrated into sub-swarms of 7-12 dikes per km2. Based on transects through four sub-swarms, dikes become more aligned, more frequent, thinner, and more closely spaced from northwest to southeast across the southern Chief Joseph swarm. Fewer than 2% of dikes, and less than 0.5% of cumulative dike length, had caused extensive melting in their wallrock. In the Cornucopia sub-swarm, numerical modeling of cross-cutting and compound dikes suggests that magmatic activity occurred intermittently over 2-4 years. Compositional data collected from -250 southern Chief Joseph dikes indicate that most are Grande Ronde Basalt, although isolated Imnaha and Dodge (Eckler Mountain Member, Wanapum Basalt) dikes also occur. Imnaha dikes are compositionally primitive, whereas Grande Ronde and Dodge dikes are more evolved. Subtle compositional differences between sub-swarms of Grande Ronde dikes suggest that each sub-swarm represents a discrete episode of Grande Ronde volcanism. Title: Feeder dikes to the Columbia River flood basalts : underpinnings of a large igneous province Author: Petcovic, Heather L. Feeder dikes to the Columbia River Basalt Group (CRBG) large igneous province provide a rare opportunity to examine magma transport through the shallow crust during flood basalt eruptions. Over 70% of the CRBG erupted from the Chief Joseph dike swarm, which is exposed across southeastern Washington, eastern Oregon, and western Idaho. The four manuscripts of this dissertation examine physical, thermal, and compositional characteristics of dikes from the southern Chief Joseph swarm. The majority of CRBG dikes are chilled against their wallrock, however, rare dikes have induced partial melting in their wallrock. Melt zones in tonalite wallrock adjacent to the Maxwell Lake dike are up to 4 in thick and contain up to 47 volume percent quenched silicic melt produced from dehydration-melting reactions involvir biotite, hornblende, quartz, orthoclase, and plagioclase. Melt zones record the thermal history of basalt flow and cooling in the Maxwell Lake dike, a feeder to Wapshilla Ridge flows (Grande Ronde Basalt). Results of one- and two-dimensional numerical modeling suggest that basalt flowed in the Maxwell Lake dike for 3-4 years, yielding maximum eruption rates of 3.4-4.6 km3/day for typical Wapshilla Ridge flows. The Maxwell Lake dike likely represents an upper crustal exposure of a long-lived point source in the CRBG. Chief Joseph dikes are concentrated into sub-swarms of 7-12 dikes per km2. Based on transects through four sub-swarms, dikes become more aligned, more frequent, thinner, and more closely spaced from northwest to southeast across the southern Chief Joseph swarm. Fewer than 2% of dikes, and less than 0.5% of cumulative dike length, had caused extensive melting in their wallrock. In the Cornucopia sub-swarm, numerical modeling of cross-cutting and compound dikes suggests that magmatic activity occurred intermittently over 2-4 years. Compositional data collected from -250 southern Chief Joseph dikes indicate that most are Grande Ronde Basalt, although isolated Imnaha and Dodge (Eckler Mountain Member, Wanapum Basalt) dikes also occur. Imnaha dikes are compositionally primitive, whereas Grande Ronde and Dodge dikes are more evolved. Subtle compositional differences between sub-swarms of Grande Ronde dikes suggest that each sub-swarm represents a discrete episode of Grande Ronde volcanism. Close

• 14. [Article] Evaluating the restoration potential of black cottonwood (Populus trichocarpa) from multiple scales of observation, Grande Ronde River Basin, Oregon, USA

  As a key factor contributing to slope stability, in-stream habitat for aquatic species (e.g., salmonids), nutrient cycling, and corridors for upland species, riparian vegetation and its maintenance is ...

  Citation × Citation Citation Abstract Copy Title: Evaluating the restoration potential of black cottonwood (Populus trichocarpa) from multiple scales of observation, Grande Ronde River Basin, Oregon, USA Author: Hines, Cynthia A. As a key factor contributing to slope stability, in-stream habitat for aquatic species (e.g., salmonids), nutrient cycling, and corridors for upland species, riparian vegetation and its maintenance is of critical conservation importance. Subsequently, the chronic degradation of aquatic and riparian ecosystems in the semi-arid and arid landscapes of the western U.S. is the focus of many recent research efforts. A study was undertaken to investigate historic and current black cottonwood populations in the Grande Ronde River Basin, northeastern Oregon, U.S.A., and evaluate restoration potential given present-day fluvial-geomorphic conditions and reproductive strategies. Black cottonwood (Populus trichocarpa), a dominant tree species in these semi-arid systems, has been severely impacted by intensive grazing, irrigation, and land conversion activities over the past one and a half centuries. With the explicit incorporation of space and time, a simple conceptual framework was developed to examine the ecological restoration potential of black cottonwood from ecological and evolutionary perspectives. Restoration potential is defined in this study in terms of availability of suitable habitat and source (i.e., seedpool) for future generations. Digital analyses of aerial photographs reveal changes in the extent, numbers, and total area of cottonwood communities and habitat since 1937. Restoration potential is evaluated using historic stream flow records, stream cross-section analysis to predict current stream discharge, and DNA RAPD procedures to assess the effects of changing stream geomorphology and disturbance regimes on cottonwood reproductive strategies. Optimal spatial and temporal conditions for potential restoration locations of black cottonwood have been identified relative to channel morphology and flood events (e.g., frequency and magnitude). This multiple scale mechnistic approach is used to evaluate the feasibility of restoration efforts toward the re-establishment of viable black cottonwood riparian plant communities in two sites in the upper Grande Ronde River Basin. Title: Evaluating the restoration potential of black cottonwood (Populus trichocarpa) from multiple scales of observation, Grande Ronde River Basin, Oregon, USA Author: Hines, Cynthia A. As a key factor contributing to slope stability, in-stream habitat for aquatic species (e.g., salmonids), nutrient cycling, and corridors for upland species, riparian vegetation and its maintenance is of critical conservation importance. Subsequently, the chronic degradation of aquatic and riparian ecosystems in the semi-arid and arid landscapes of the western U.S. is the focus of many recent research efforts. A study was undertaken to investigate historic and current black cottonwood populations in the Grande Ronde River Basin, northeastern Oregon, U.S.A., and evaluate restoration potential given present-day fluvial-geomorphic conditions and reproductive strategies. Black cottonwood (Populus trichocarpa), a dominant tree species in these semi-arid systems, has been severely impacted by intensive grazing, irrigation, and land conversion activities over the past one and a half centuries. With the explicit incorporation of space and time, a simple conceptual framework was developed to examine the ecological restoration potential of black cottonwood from ecological and evolutionary perspectives. Restoration potential is defined in this study in terms of availability of suitable habitat and source (i.e., seedpool) for future generations. Digital analyses of aerial photographs reveal changes in the extent, numbers, and total area of cottonwood communities and habitat since 1937. Restoration potential is evaluated using historic stream flow records, stream cross-section analysis to predict current stream discharge, and DNA RAPD procedures to assess the effects of changing stream geomorphology and disturbance regimes on cottonwood reproductive strategies. Optimal spatial and temporal conditions for potential restoration locations of black cottonwood have been identified relative to channel morphology and flood events (e.g., frequency and magnitude). This multiple scale mechnistic approach is used to evaluate the feasibility of restoration efforts toward the re-establishment of viable black cottonwood riparian plant communities in two sites in the upper Grande Ronde River Basin. Close

• 15. [Article] The ecology of riparian ecosystems of Northeast Oregon : shrub recovery at Meadow Creek and the structure and biomass of headwater Upper Grande Ronde ecosystems

  Riparian ecosystems play numerous and essential roles related to the quality and flow of water, and food/habitat for fish, and varieties of wildlife. Due to lateral and linear linkages throughout the landscape, ...

  Citation × Citation Citation Abstract Copy Title: The ecology of riparian ecosystems of Northeast Oregon : shrub recovery at Meadow Creek and the structure and biomass of headwater Upper Grande Ronde ecosystems Author: Case, Richard L. Riparian ecosystems play numerous and essential roles related to the quality and flow of water, and food/habitat for fish, and varieties of wildlife. Due to lateral and linear linkages throughout the landscape, these zones influence the integrity of the terrestrial as well as the entire aquatic-riverine ecosystem. Since Euro-American settlement in the West, the structure and condition of many riparian ecosystems has been significantly altered. To provide tools and an ecological perspective related to riparian restoration and management, and to document late 20th century headwater riparian structure and biomass in the Upper Grande Ronde Basin, this research project was undertaken. At Meadow Creek, the response of riparian hardwood species to the termination of livestock grazing was quantified. Regression equations were developed to predict shrub biomass. Permanently marked hardwood plants were measured annually to quantify parameters of growth (height, crown area, mainstem diameter, number of stems, biomass). Permanent belt transects on gravel bars were utilized to quantify rates of shrub establishment. Elk/deer-proof exclosures allowed the quantification of the browsing influence of wild ungulates. In 1991, initial shrub heights and densities reflected decades of grazing pressure. Mean heights of515 woody plants (14 species) was 47 cm and densities on gravel bars averaged 10.7 plants/100m². After two seasons without livestock grazing, mean crown volumes of willows (Salix spp.) increased 550% inside of wild ungulate exclosures and 195% outside, black cottonwood (Populus trichocarpa) 773% inside and 808% outside, and thin-leaf alder (Almis incana) 1046% inside and 198% outside, respectively. Willows were significantly impeded (p<0.Ol) mule deer and Rocky Mountain elk, alder samples were too small to statistically test, and cottonwood was not significantly impeded. However, impacts by deer and elk may be exaggerated due to high densities and the ungulate density-dynamics unique within the 77 km² Starkey Experimental Forest big-game enclosure surrounding the study site. Establishment rates are low at this time, i.e., only 10% of previously suppressed willows produced catkins. Although in transects densities increased by 5 new woody plants/lOOm² (50m of streambank). Other non-anthropogenic factors influencing the recovery of shrubs, included beaver which removed mainstems from 20% of willows, 11% of thin-leaf alder, and 4% of black cottonwood, and active insect defoliation which was noted on 16% of willows, 7% of thin-leaf alder, and 0% of black cottonwood. Crude protein levels measured in willow and alder leaves was relatively high (16.1 to 16.3%) helping to explain their palatability and use by wild and domestic herbivores. Few studies have quantified biomass, structure and composition of headwater riparian ecosystems. Data such as this are important given their dominant roles in ecosystem biodiversity, and aquatic function. To document relatively intact forested headwater ripanan conditions in the Upper Grande Ronde Basin, the biomass, structure and composition along six headwater reaches was quantified. Sampling was done using a nested belt transect/plot arrangement along 500 meter reaches. Total aboveground biomass (TAGB) ranged from 203 to 261 Mg/ha, with overstory conifers contributing 101 to 177 Mg/ha. Living understory components (saplings, seedlings, shrubs, and herbs) comprised 5 to 18 Mg/ha (2 to 9% of TAGB), while forest floor detrital accumulations comprised 65 to 101 Mg/ha (29 to 42% of TAGB). Average shade per day for July, 1993 ranged between 53% and 75%, reducing the unshaded solar energy potential of 2390 Mj/day to between 680 and 1280 Mj/day striking each m² of stream surface. This baseline reference information can serve in multi-disciplined research, as well as, be a basis for long term studies of natural systems responding to changing climate and different resource management scenarios. Title: The ecology of riparian ecosystems of Northeast Oregon : shrub recovery at Meadow Creek and the structure and biomass of headwater Upper Grande Ronde ecosystems Author: Case, Richard L. Riparian ecosystems play numerous and essential roles related to the quality and flow of water, and food/habitat for fish, and varieties of wildlife. Due to lateral and linear linkages throughout the landscape, these zones influence the integrity of the terrestrial as well as the entire aquatic-riverine ecosystem. Since Euro-American settlement in the West, the structure and condition of many riparian ecosystems has been significantly altered. To provide tools and an ecological perspective related to riparian restoration and management, and to document late 20th century headwater riparian structure and biomass in the Upper Grande Ronde Basin, this research project was undertaken. At Meadow Creek, the response of riparian hardwood species to the termination of livestock grazing was quantified. Regression equations were developed to predict shrub biomass. Permanently marked hardwood plants were measured annually to quantify parameters of growth (height, crown area, mainstem diameter, number of stems, biomass). Permanent belt transects on gravel bars were utilized to quantify rates of shrub establishment. Elk/deer-proof exclosures allowed the quantification of the browsing influence of wild ungulates. In 1991, initial shrub heights and densities reflected decades of grazing pressure. Mean heights of515 woody plants (14 species) was 47 cm and densities on gravel bars averaged 10.7 plants/100m². After two seasons without livestock grazing, mean crown volumes of willows (Salix spp.) increased 550% inside of wild ungulate exclosures and 195% outside, black cottonwood (Populus trichocarpa) 773% inside and 808% outside, and thin-leaf alder (Almis incana) 1046% inside and 198% outside, respectively. Willows were significantly impeded (p<0.Ol) mule deer and Rocky Mountain elk, alder samples were too small to statistically test, and cottonwood was not significantly impeded. However, impacts by deer and elk may be exaggerated due to high densities and the ungulate density-dynamics unique within the 77 km² Starkey Experimental Forest big-game enclosure surrounding the study site. Establishment rates are low at this time, i.e., only 10% of previously suppressed willows produced catkins. Although in transects densities increased by 5 new woody plants/lOOm² (50m of streambank). Other non-anthropogenic factors influencing the recovery of shrubs, included beaver which removed mainstems from 20% of willows, 11% of thin-leaf alder, and 4% of black cottonwood, and active insect defoliation which was noted on 16% of willows, 7% of thin-leaf alder, and 0% of black cottonwood. Crude protein levels measured in willow and alder leaves was relatively high (16.1 to 16.3%) helping to explain their palatability and use by wild and domestic herbivores. Few studies have quantified biomass, structure and composition of headwater riparian ecosystems. Data such as this are important given their dominant roles in ecosystem biodiversity, and aquatic function. To document relatively intact forested headwater ripanan conditions in the Upper Grande Ronde Basin, the biomass, structure and composition along six headwater reaches was quantified. Sampling was done using a nested belt transect/plot arrangement along 500 meter reaches. Total aboveground biomass (TAGB) ranged from 203 to 261 Mg/ha, with overstory conifers contributing 101 to 177 Mg/ha. Living understory components (saplings, seedlings, shrubs, and herbs) comprised 5 to 18 Mg/ha (2 to 9% of TAGB), while forest floor detrital accumulations comprised 65 to 101 Mg/ha (29 to 42% of TAGB). Average shade per day for July, 1993 ranged between 53% and 75%, reducing the unshaded solar energy potential of 2390 Mj/day to between 680 and 1280 Mj/day striking each m² of stream surface. This baseline reference information can serve in multi-disciplined research, as well as, be a basis for long term studies of natural systems responding to changing climate and different resource management scenarios. Close

• 16. [Article] Oregon State Game Commission bulletin; Vol.22 No.6 (November-December 1967)

  Contents: Senate Bill 8 Becomes Law - p.2; Can You Tell Me? [Receiving inquiries about fishing and hunting regulations] - p.3, 7-8; Steelhead Fishing Grande Ronde River - p.4-5; Cougar [Photos] - p.6; ...

  Citation × Citation Citation Abstract Copy Title: Oregon State Game Commission bulletin; Vol.22 No.6 (November-December 1967) Author: Oregon. State Game Commission Contents: Senate Bill 8 Becomes Law - p.2; Can You Tell Me? [Receiving inquiries about fishing and hunting regulations] - p.3, 7-8; Steelhead Fishing Grande Ronde River - p.4-5; Cougar [Photos] - p.6; The California Murre - p.8 Title: Oregon State Game Commission bulletin; Vol.22 No.6 (November-December 1967) Author: Oregon. State Game Commission Contents: Senate Bill 8 Becomes Law - p.2; Can You Tell Me? [Receiving inquiries about fishing and hunting regulations] - p.3, 7-8; Steelhead Fishing Grande Ronde River - p.4-5; Cougar [Photos] - p.6; The California Murre - p.8 Close

• 17. [Article] Results of trip to Snake River : 28 September -- 4 October 1957

  The mail boat trip was taken from Lewiston to Hells Canyon and return. Bathythermograph observations were made in deep holes at Buffalo Eddy, Nez Perce Dam site, and near Mountain Sheep Dam site. Thermograph ...

  Citation × Citation Citation Abstract Copy Title: Results of trip to Snake River : 28 September -- 4 October 1957 Author: Oregon State College. School of Science, Burt, Wayne V., U.S. Fish and Wildlife Service The mail boat trip was taken from Lewiston to Hells Canyon and return. Bathythermograph observations were made in deep holes at Buffalo Eddy, Nez Perce Dam site, and near Mountain Sheep Dam site. Thermograph sites on the Grande Ronde River were evaluated. A number of lakes, reservoirs, and dams were visited enroute to Lewiston. Title: Results of trip to Snake River : 28 September -- 4 October 1957 Author: Oregon State College. School of Science, Burt, Wayne V., U.S. Fish and Wildlife Service The mail boat trip was taken from Lewiston to Hells Canyon and return. Bathythermograph observations were made in deep holes at Buffalo Eddy, Nez Perce Dam site, and near Mountain Sheep Dam site. Thermograph sites on the Grande Ronde River were evaluated. A number of lakes, reservoirs, and dams were visited enroute to Lewiston. Close

• 18. [Article] Ecology of woody riparian vegetation in tributaries of the Upper Grande Ronde River basin, Oregon

  Two studies on Catherine Creek and Meadow Creek of the Upper Grande Ronde River basin, quantified several physical and biotic influences on woody riparian community composition and structure. The Catherine ...

  Citation × Citation Citation Abstract Copy Title: Ecology of woody riparian vegetation in tributaries of the Upper Grande Ronde River basin, Oregon Author: Lytjen, Danna J. Two studies on Catherine Creek and Meadow Creek of the Upper Grande Ronde River basin, quantified several physical and biotic influences on woody riparian community composition and structure. The Catherine Creek study examined the association of woody riparian species with elevational and geomorphic gradients. The Meadow Creek study examined the influence of mammal herbivory on composition and abundance of woody riparian species. At Catherine Creek, twenty nine plots were established at 50 m intervals of elevation from near the stream origin at 2207 m in the Wallowa Mountains to the foothills of the Grande Ronde Valley at 988 m. Woody plant community composition was associated with the dominant environmental variable, elevation. Distribution of dominant riparian species was strongly associated with fluvial surfaces. Black cottonwood (Populus balsamifera) was associated with gravel and cobble bars proximal to the stream channel, and along with ponderosa pine (Pinus ponderosa) was also associated with elevated boulder bars. Alders (A. incana and A. viridis) and willows (Salix bebbiana, S. boothii, S. exigua, S. lucida, S. melanopsis, S. prolixa, and S. sitchensis) were associated with annual floodplains. At Meadow Creek, grazing by cattle was ended in 1991 on the entire study reach and three deer and elk exclosures were built within the reach adjacent to the creek. Inside deer/elk exclosures from 1991 to 1995, mean heights of tagged cottonwoods, willows, and alders increased by 86% to 180%. Outside exclosures, mean heights of cottonwoods and alders increased 109% and 99% respectively, but willows showed little change in height. Both inside and outside of exclosures mean crown volume of cottonwoods increased over 1000% and mean crown volume of alders increased over 600%. Willow volume inside exclosures increased 376% in root sprouting (clonal) species and 528% in crown sprouting (non-clonal) species, while outside of exclosures volume increased 79% and 144% respectively. On both sides of exclosure fences, beaver herbivory had a significant effect on cottonwood height growth in 1994 and 1995, and on height and crown volume growth of willows in 1995. Over 50% of stem density increase on transects was attributable to expansion within two large clones of Salix melanopsis inside exclosures. Excluding these two clones, overall woody plant density increased by 72% from 3.7 plants per 100 m² of transect in 1991 to 6.3 plants per 100 m² of transect in 1995. Title: Ecology of woody riparian vegetation in tributaries of the Upper Grande Ronde River basin, Oregon Author: Lytjen, Danna J. Two studies on Catherine Creek and Meadow Creek of the Upper Grande Ronde River basin, quantified several physical and biotic influences on woody riparian community composition and structure. The Catherine Creek study examined the association of woody riparian species with elevational and geomorphic gradients. The Meadow Creek study examined the influence of mammal herbivory on composition and abundance of woody riparian species. At Catherine Creek, twenty nine plots were established at 50 m intervals of elevation from near the stream origin at 2207 m in the Wallowa Mountains to the foothills of the Grande Ronde Valley at 988 m. Woody plant community composition was associated with the dominant environmental variable, elevation. Distribution of dominant riparian species was strongly associated with fluvial surfaces. Black cottonwood (Populus balsamifera) was associated with gravel and cobble bars proximal to the stream channel, and along with ponderosa pine (Pinus ponderosa) was also associated with elevated boulder bars. Alders (A. incana and A. viridis) and willows (Salix bebbiana, S. boothii, S. exigua, S. lucida, S. melanopsis, S. prolixa, and S. sitchensis) were associated with annual floodplains. At Meadow Creek, grazing by cattle was ended in 1991 on the entire study reach and three deer and elk exclosures were built within the reach adjacent to the creek. Inside deer/elk exclosures from 1991 to 1995, mean heights of tagged cottonwoods, willows, and alders increased by 86% to 180%. Outside exclosures, mean heights of cottonwoods and alders increased 109% and 99% respectively, but willows showed little change in height. Both inside and outside of exclosures mean crown volume of cottonwoods increased over 1000% and mean crown volume of alders increased over 600%. Willow volume inside exclosures increased 376% in root sprouting (clonal) species and 528% in crown sprouting (non-clonal) species, while outside of exclosures volume increased 79% and 144% respectively. On both sides of exclosure fences, beaver herbivory had a significant effect on cottonwood height growth in 1994 and 1995, and on height and crown volume growth of willows in 1995. Over 50% of stem density increase on transects was attributable to expansion within two large clones of Salix melanopsis inside exclosures. Excluding these two clones, overall woody plant density increased by 72% from 3.7 plants per 100 m² of transect in 1991 to 6.3 plants per 100 m² of transect in 1995. Close

• 19. [Article] Revegetation with Carex nebrascensis and Carex utriculata following reconstruction in a NE Oregon meadow stream

  Riparian vegetation is an essential component for the maintenance and/or repair of channel stability and function. Sedges within low-gradient riparian systems provide the structure necessary for sediment ...

  Citation × Citation Citation Abstract Copy Title: Revegetation with Carex nebrascensis and Carex utriculata following reconstruction in a NE Oregon meadow stream Author: Quistberg, Sarah E. Riparian vegetation is an essential component for the maintenance and/or repair of channel stability and function. Sedges within low-gradient riparian systems provide the structure necessary for sediment trapping leading to channel narrowing through bank building processes. Planting success in riparian restoration projects has often failed due to inappropriate species selection, planting locations and/or methodologies. Stream restoration efforts utilizing channel reconstruction methods are increasing in number across the West thus emphasizing the need for knowledge on revegetation methods. Planting success in a recently constructed channel is essential because the lack of vegetation makes the channel highly susceptible to erosion. Sedges play an important role in the stability of low gradient, fine-textured stream channels. Two native sedges, Carex nebrascensis (Nebraska sedge) and Carex utriculata (beaked sedge) are often used in riparian restoration within the West because they have extensive root systems that can provide bank stability in fine-sediment channels. Survival and vegetative reproduction were evaluated on greenhouse grown plugs of these two sedge species following transplanting within a reconstructed NE Oregon meadow stream. Sedge plugs were planted on two fluvial surfaces along the stream: depositional (point bars) and erosional surfaces (straight) at or below bankfull level. A second study was performed to evaluate the effect of Cirsium arvense (Canada thistle) presence on sedge transplant survival and vegetative reproduction. This was performed only on erosional planting locations. Depths to groundwater and soil moisture were also recorded at each planting location. Survival at the end of the first growing season in the first study was the same for both species, but shoot numbers were greater for Carex nebrascensis (98 shoots/m²) compared with Carex utriculata (84 shoots/m²). No differences were observed between shoot numbers by species at the end of the second growing season. Greater shoot numbers also occurred on depositional planting locations (117 and 165 shoots/m²) compared to erosional planting locations (65 and 59 shoots/m²) at the end of the first and second growing seasons. Transplant loss due to scour from high flows was greater at erosional planting locations (48%) than at depositional planting surfaces (19%). Sedge transplant loss from scour during high flows was greater for Carex utriculata transplants (44%) than for Carex nebrascensis transplants (23%). Presence of Cirsium arvense was observed to be associated with a reduction in vegetative reproduction during the first growing season but not at the end of the second growing season. Carex nebrascensis produced more shoots than Carex utriculata regardless of thistle presence for both growing seasons probably due to depth to groundwater. Transplant loss due to scour from high flows was greater for Carex utriculata (55%) compared to Carex nebrascensis (28%). These results suggested that revegetation success will be increased if sedges are planted on depositional geomorphic surfaces within reconstructed meadow channels. Cirsium arvense may be controlled following sedge transplanting during the first growing season to increase vegetative growth. These results also suggested that Carex nebrascensis is an appropriate species for transplanting at sites with water tables deeper than 30 cm. Title: Revegetation with Carex nebrascensis and Carex utriculata following reconstruction in a NE Oregon meadow stream Author: Quistberg, Sarah E. Riparian vegetation is an essential component for the maintenance and/or repair of channel stability and function. Sedges within low-gradient riparian systems provide the structure necessary for sediment trapping leading to channel narrowing through bank building processes. Planting success in riparian restoration projects has often failed due to inappropriate species selection, planting locations and/or methodologies. Stream restoration efforts utilizing channel reconstruction methods are increasing in number across the West thus emphasizing the need for knowledge on revegetation methods. Planting success in a recently constructed channel is essential because the lack of vegetation makes the channel highly susceptible to erosion. Sedges play an important role in the stability of low gradient, fine-textured stream channels. Two native sedges, Carex nebrascensis (Nebraska sedge) and Carex utriculata (beaked sedge) are often used in riparian restoration within the West because they have extensive root systems that can provide bank stability in fine-sediment channels. Survival and vegetative reproduction were evaluated on greenhouse grown plugs of these two sedge species following transplanting within a reconstructed NE Oregon meadow stream. Sedge plugs were planted on two fluvial surfaces along the stream: depositional (point bars) and erosional surfaces (straight) at or below bankfull level. A second study was performed to evaluate the effect of Cirsium arvense (Canada thistle) presence on sedge transplant survival and vegetative reproduction. This was performed only on erosional planting locations. Depths to groundwater and soil moisture were also recorded at each planting location. Survival at the end of the first growing season in the first study was the same for both species, but shoot numbers were greater for Carex nebrascensis (98 shoots/m²) compared with Carex utriculata (84 shoots/m²). No differences were observed between shoot numbers by species at the end of the second growing season. Greater shoot numbers also occurred on depositional planting locations (117 and 165 shoots/m²) compared to erosional planting locations (65 and 59 shoots/m²) at the end of the first and second growing seasons. Transplant loss due to scour from high flows was greater at erosional planting locations (48%) than at depositional planting surfaces (19%). Sedge transplant loss from scour during high flows was greater for Carex utriculata transplants (44%) than for Carex nebrascensis transplants (23%). Presence of Cirsium arvense was observed to be associated with a reduction in vegetative reproduction during the first growing season but not at the end of the second growing season. Carex nebrascensis produced more shoots than Carex utriculata regardless of thistle presence for both growing seasons probably due to depth to groundwater. Transplant loss due to scour from high flows was greater for Carex utriculata (55%) compared to Carex nebrascensis (28%). These results suggested that revegetation success will be increased if sedges are planted on depositional geomorphic surfaces within reconstructed meadow channels. Cirsium arvense may be controlled following sedge transplanting during the first growing season to increase vegetative growth. These results also suggested that Carex nebrascensis is an appropriate species for transplanting at sites with water tables deeper than 30 cm. Close

• 20. [Article] The geology of the Nicolai Mountain-Gnat Creek area, Clatsop County, northwestern Oregon

  Twelve rock units, from upper Eocene to middle Miocene are exposed in the Nicolai Mountain-Gnat Creek area. They are, from oldest to youngest: Pittsburg Bluff Formation; Oswald West mudstone; Big Creek ...

  Citation × Citation Citation Abstract Copy Title: The geology of the Nicolai Mountain-Gnat Creek area, Clatsop County, northwestern Oregon Author: Murphy, Thomas M. Twelve rock units, from upper Eocene to middle Miocene are exposed in the Nicolai Mountain-Gnat Creek area. They are, from oldest to youngest: Pittsburg Bluff Formation; Oswald West mudstone; Big Creek sandstone, upper Silver Point mudstone, and Pipeline mudstone members of the Astoria Formation; Depoe Bay Basalt; Grande Ronde Basalt; Cape Foulweather Basalt; and sandstone correlative to the Vantage Member of the Ellensburg Formation; Frenchman Springs Member of the Wanapum Basalt; Clifton, Formation (defined by author); and Pomona Member of the Saddle Mountains Basalt. Upper Eocene Pittsburg Bluff Formation is a fine-grained sandstone and laminated siltstone deposited in an inner to middle continental shelf environment. Concordant onlapping by the upper Oligocene, middle shelf to upper slope glauconitic Oswald West mudstone, establishes a tie between the northeastern and northwestern Oregon Coast Range stratigraphies. The lower to middle Miocene Astoria Formation represents another marine onlap sequence, beginning with the fine-grained cross-bedded inner shelf Big Creek sandstone member. The overlying laminted upper Silver Point and Pipeline mudstone members were deposited in a deepening middle shelf to upper slope environment. The middle Miocene tholeiitic basalts extruded from two sources. Grande Ronde, Frenchman Springs, and Pomona basalts of the Columbia River Group erupted from fissures east of the Cascades and flowed down an ancestral Columbia River valley entering the sea in the study area. Simultaneously, petrologically similar but less voluminous Depoe Bay and Cape Foulweather are correlative to the low MgO Grande Ronde and Frenchman Springs in the study area. Abundant dikes and sills and the bathyal mudstone interbeds suggest that the coastal pillow basalts extruded locally onto the sea floor. Subaerial plateau-derived flows are associated with cross-bedded, fluvial to shallow marine arkosic sandstone interbeds. Some of these subaerial lavas flowed into the sea, forming "lava deltas" of foreset pillow palagonite and possibly "invasive" sills. The basalt stratigraphy allows a nearly flow by flow correlation of Grande Ronde and Frenchman Springs units from the Clackamas River area (Western Cascades) into this study area. The presence of Pomona Member in this area is the first substantiated recognition of this petrologically and chemically distinctive subaerial flow in northwestern Oregon. The 200-meter thick Clifton formation (previously called the Pliocene (?) sandstone at Clifton) is now dated by diatom assemblages and stratigraphic position as middle Miocene in age. Three lithofacies are recognized. Facies 1, at the base and top of the unit, is an arkosic, fine- to coarse- grained sandstone with cross-bedding, vertical Rosselia burrows, lignitic coal beds, and rare molluscan shells. It represents a river mouth and shallow marine offshore bar deposit. Facies 2, in the middle of the formation, consitst of well-laminated diatom-bearing carbonaceous and micaceous shelf/slope siltstones with thin fine-grained turbidite sandstones. Facies consists of channelized siltstone breccias, chaotic debris flows, thick amalgamated arkosic grain flows, structureless sandstones, and minor volcanic pebble conglomerates. These lithologies suggest a canyon head and slump deposit formed as a submarine channel cut into the shelf/slope siltstones of Facies 2. Sandstone petrography and grain size analyses indicate that the detritus of the Clifton and other sandstones in the area was derived from acid igneous, metamorphic, and intermediate volcanic provenances similar to those drained by the Columbia River today. Despite high measured permeabilities, breaching limits the reservoir potential of the sandstone. Mudstone units are immature to mature hydrocarbon source rocks. A potential for gas exists in the Cowlitz or its equivalent in the subsurface and in the Clifton channel sandstones projected into the offshore area. Title: The geology of the Nicolai Mountain-Gnat Creek area, Clatsop County, northwestern Oregon Author: Murphy, Thomas M. Twelve rock units, from upper Eocene to middle Miocene are exposed in the Nicolai Mountain-Gnat Creek area. They are, from oldest to youngest: Pittsburg Bluff Formation; Oswald West mudstone; Big Creek sandstone, upper Silver Point mudstone, and Pipeline mudstone members of the Astoria Formation; Depoe Bay Basalt; Grande Ronde Basalt; Cape Foulweather Basalt; and sandstone correlative to the Vantage Member of the Ellensburg Formation; Frenchman Springs Member of the Wanapum Basalt; Clifton, Formation (defined by author); and Pomona Member of the Saddle Mountains Basalt. Upper Eocene Pittsburg Bluff Formation is a fine-grained sandstone and laminated siltstone deposited in an inner to middle continental shelf environment. Concordant onlapping by the upper Oligocene, middle shelf to upper slope glauconitic Oswald West mudstone, establishes a tie between the northeastern and northwestern Oregon Coast Range stratigraphies. The lower to middle Miocene Astoria Formation represents another marine onlap sequence, beginning with the fine-grained cross-bedded inner shelf Big Creek sandstone member. The overlying laminted upper Silver Point and Pipeline mudstone members were deposited in a deepening middle shelf to upper slope environment. The middle Miocene tholeiitic basalts extruded from two sources. Grande Ronde, Frenchman Springs, and Pomona basalts of the Columbia River Group erupted from fissures east of the Cascades and flowed down an ancestral Columbia River valley entering the sea in the study area. Simultaneously, petrologically similar but less voluminous Depoe Bay and Cape Foulweather are correlative to the low MgO Grande Ronde and Frenchman Springs in the study area. Abundant dikes and sills and the bathyal mudstone interbeds suggest that the coastal pillow basalts extruded locally onto the sea floor. Subaerial plateau-derived flows are associated with cross-bedded, fluvial to shallow marine arkosic sandstone interbeds. Some of these subaerial lavas flowed into the sea, forming "lava deltas" of foreset pillow palagonite and possibly "invasive" sills. The basalt stratigraphy allows a nearly flow by flow correlation of Grande Ronde and Frenchman Springs units from the Clackamas River area (Western Cascades) into this study area. The presence of Pomona Member in this area is the first substantiated recognition of this petrologically and chemically distinctive subaerial flow in northwestern Oregon. The 200-meter thick Clifton formation (previously called the Pliocene (?) sandstone at Clifton) is now dated by diatom assemblages and stratigraphic position as middle Miocene in age. Three lithofacies are recognized. Facies 1, at the base and top of the unit, is an arkosic, fine- to coarse- grained sandstone with cross-bedding, vertical Rosselia burrows, lignitic coal beds, and rare molluscan shells. It represents a river mouth and shallow marine offshore bar deposit. Facies 2, in the middle of the formation, consitst of well-laminated diatom-bearing carbonaceous and micaceous shelf/slope siltstones with thin fine-grained turbidite sandstones. Facies consists of channelized siltstone breccias, chaotic debris flows, thick amalgamated arkosic grain flows, structureless sandstones, and minor volcanic pebble conglomerates. These lithologies suggest a canyon head and slump deposit formed as a submarine channel cut into the shelf/slope siltstones of Facies 2. Sandstone petrography and grain size analyses indicate that the detritus of the Clifton and other sandstones in the area was derived from acid igneous, metamorphic, and intermediate volcanic provenances similar to those drained by the Columbia River today. Despite high measured permeabilities, breaching limits the reservoir potential of the sandstone. Mudstone units are immature to mature hydrocarbon source rocks. A potential for gas exists in the Cowlitz or its equivalent in the subsurface and in the Clifton channel sandstones projected into the offshore area. Close