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• 1. [Article] A preliminary investigation of the lithological characteristics of the Troutdale Formation in portions of the Camas, Sandy, Washougal, and Bridal Veil quadrangles

  The study area encompasses a region of about 80 square kilometers, centered about Corbett, Oregon. Sieve analyses suggest that the Troutdale Formation is composed of a conglomerate, a coarse-grained sandstone, ...

  Citation × Citation Citation Abstract Copy Title: A preliminary investigation of the lithological characteristics of the Troutdale Formation in portions of the Camas, Sandy, Washougal, and Bridal Veil quadrangles Author: Cole, David Lee Year: 1982 The study area encompasses a region of about 80 square kilometers, centered about Corbett, Oregon. Sieve analyses suggest that the Troutdale Formation is composed of a conglomerate, a coarse-grained sandstone, and a siltstone lithofacies. Measured sections data show that 56 to 60 percent of the Troutdale Formation's exposures are composed of the conglomerate lithofacies. The coarsegrained sandstone lithofacies makes up 34 to 38 percent, while the siltstone lithofacies makes up only 4 to 8 percent. Pebble count data show that the representation of basalt varies from 69 to 100 percent, with an average of 85 percent, while quartzite varies from 0 to 25 percent, with an average of 9 percent. Geochemical data show that at least one formal member and two informal members of the Columbia River Basalt Group (Frenchman Springs, Grande Ronde High Mg, and Grande Ronde Low Mg) compose part of the detritus. The geochemical data also show that rocks of the Boring Lavas or similar lavas are intercalated with the Troutdale Formation, high in the section. Grain mount petrographic data show that volcanic rock fragments are the dominant component in the coarse sand fraction of the Troutdale Formation. Many of the volcanic rock fragments contain brown glass with an index of refraction of 1.583 +/- 0.001, which indicates a mafic composition {silica content of 50 +/- 1 percent). The representation of volcanic rock fragments varies from 29 to 98 percent, with an average of 75 percent. Sedimentary rock fragments, such as chert, vary from 0 to 17 percent, with an average of 5 percent. Biotite ranges from 0 to 12 percent, with an average of 2 percent. Two-thirds of the samples which contain sedimentary rock fragments also contain biotite. Orthopyroxene varies from 0 to 18 percent, with an average of 5 percent. 2 The samples with the three greatest amounts of orthopyroxene do not contain sedimentary rock fragments or biotite. Title: A preliminary investigation of the lithological characteristics of the Troutdale Formation in portions of the Camas, Sandy, Washougal, and Bridal Veil quadrangles Author: Cole, David Lee Year: 1982 The study area encompasses a region of about 80 square kilometers, centered about Corbett, Oregon. Sieve analyses suggest that the Troutdale Formation is composed of a conglomerate, a coarse-grained sandstone, and a siltstone lithofacies. Measured sections data show that 56 to 60 percent of the Troutdale Formation's exposures are composed of the conglomerate lithofacies. The coarsegrained sandstone lithofacies makes up 34 to 38 percent, while the siltstone lithofacies makes up only 4 to 8 percent. Pebble count data show that the representation of basalt varies from 69 to 100 percent, with an average of 85 percent, while quartzite varies from 0 to 25 percent, with an average of 9 percent. Geochemical data show that at least one formal member and two informal members of the Columbia River Basalt Group (Frenchman Springs, Grande Ronde High Mg, and Grande Ronde Low Mg) compose part of the detritus. The geochemical data also show that rocks of the Boring Lavas or similar lavas are intercalated with the Troutdale Formation, high in the section. Grain mount petrographic data show that volcanic rock fragments are the dominant component in the coarse sand fraction of the Troutdale Formation. Many of the volcanic rock fragments contain brown glass with an index of refraction of 1.583 +/- 0.001, which indicates a mafic composition {silica content of 50 +/- 1 percent). The representation of volcanic rock fragments varies from 29 to 98 percent, with an average of 75 percent. Sedimentary rock fragments, such as chert, vary from 0 to 17 percent, with an average of 5 percent. Biotite ranges from 0 to 12 percent, with an average of 2 percent. Two-thirds of the samples which contain sedimentary rock fragments also contain biotite. Orthopyroxene varies from 0 to 18 percent, with an average of 5 percent. 2 The samples with the three greatest amounts of orthopyroxene do not contain sedimentary rock fragments or biotite. Close

• 2. [Article] Tribal constructs and kinship realities : individual and family organization on the Grand Ronde Reservation from 1856

  This project examines marriage and residence patterns on the Grand Ronde Reservation between 1856 and the early 1900s. It demonstrates that indigenous cultural patterns continued despite a colonial imagination ...

  Citation × Citation Citation Abstract Copy Title: Tribal constructs and kinship realities : individual and family organization on the Grand Ronde Reservation from 1856 Author: Teverbaugh, Aeron Year: 2000 This project examines marriage and residence patterns on the Grand Ronde Reservation between 1856 and the early 1900s. It demonstrates that indigenous cultural patterns continued despite a colonial imagination that refused to see them. Members of the Confederated Tribes of the Grand Ronde continued to live in family groups much as they had in the pre-reservation era. They continued to exhibit patterns of marriage and kinship that were described in the ethnographies and by the earliest explorers in the Oregon area. Title: Tribal constructs and kinship realities : individual and family organization on the Grand Ronde Reservation from 1856 Author: Teverbaugh, Aeron Year: 2000 This project examines marriage and residence patterns on the Grand Ronde Reservation between 1856 and the early 1900s. It demonstrates that indigenous cultural patterns continued despite a colonial imagination that refused to see them. Members of the Confederated Tribes of the Grand Ronde continued to live in family groups much as they had in the pre-reservation era. They continued to exhibit patterns of marriage and kinship that were described in the ethnographies and by the earliest explorers in the Oregon area. Close

• 3. [Article] Explosion structures in Grande Ronde basalt of the Columbia Riverbasalt group, near Troy, Oregon

  Explosion structures occur in flows of Grande Ronde Basalt in the study area near Troy, Oregon. Data from nineteen stratigraphic sites indicate that the maximum number of flows that contain explosion structures ...

  Citation × Citation Citation Abstract Copy Title: Explosion structures in Grande Ronde basalt of the Columbia Riverbasalt group, near Troy, Oregon Author: Orzol, Leonard Lee Year: 1987 Explosion structures occur in flows of Grande Ronde Basalt in the study area near Troy, Oregon. Data from nineteen stratigraphic sites indicate that the maximum number of flows that contain explosion structures at any one site is six. In the informally named Troy flow, explosion structures are widespread. Title: Explosion structures in Grande Ronde basalt of the Columbia Riverbasalt group, near Troy, Oregon Author: Orzol, Leonard Lee Year: 1987 Explosion structures occur in flows of Grande Ronde Basalt in the study area near Troy, Oregon. Data from nineteen stratigraphic sites indicate that the maximum number of flows that contain explosion structures at any one site is six. In the informally named Troy flow, explosion structures are widespread. Close

• 4. [Article] Textural and mineralogical characteristics of altered Grande Ronde basalt, northeastern Oregon : a natural analog for a nuclear waste repository in basalt

  Altered flows that are low-MgO chemical types of the Grande Ronde Basalt crop out in the steep walls of the Grande Ronde River canyon near Troy, Wallowa County, Oregon. The alteration effects in these ...

  Citation × Citation Citation Abstract Copy Title: Textural and mineralogical characteristics of altered Grande Ronde basalt, northeastern Oregon : a natural analog for a nuclear waste repository in basalt Author: Trone, Paul M. Year: 1987 Altered flows that are low-MgO chemical types of the Grande Ronde Basalt crop out in the steep walls of the Grande Ronde River canyon near Troy, Wallowa County, Oregon. The alteration effects in these flows are being investigated as a natural analog system to a high level nuclear waste repository in basalt. The flows within the study are referred to as the analog flow, in which the alteration effects are the strongest, and the superjacent flow. The analog flow crops out at Grande Ronde River level and a roadcut-outcrop is developed in the flow-top breccia of this flow. The two flows have been divided into flow zones based on intraflow structures observed in the field and primary igneous textures observed in thin section. These zones include, from the base upward, the flow interior, transition, and flow-top breccia zones of the analog flow, the interflow contact zone, and the flow interior and flow-top breccia zone of the superjacent flow. The intraflow structures and textures of the transition and interflow contact zones are atypical of Grande Ronde Basalt flows. The transition zone is transitional in textures between the flow interior zone and flow-top breccia zone, and includes holocrystalline spines mantled with fused in situ breccias. The interflow contact zone reflects the dynamic interaction during the emplacement of the superjacent flow manifested as invasive basalt tongues, clasts shed from tongues, pipe vesicles and tree molds, and pockets of breccia caught up in the base of the superjacent flow. Title: Textural and mineralogical characteristics of altered Grande Ronde basalt, northeastern Oregon : a natural analog for a nuclear waste repository in basalt Author: Trone, Paul M. Year: 1987 Altered flows that are low-MgO chemical types of the Grande Ronde Basalt crop out in the steep walls of the Grande Ronde River canyon near Troy, Wallowa County, Oregon. The alteration effects in these flows are being investigated as a natural analog system to a high level nuclear waste repository in basalt. The flows within the study are referred to as the analog flow, in which the alteration effects are the strongest, and the superjacent flow. The analog flow crops out at Grande Ronde River level and a roadcut-outcrop is developed in the flow-top breccia of this flow. The two flows have been divided into flow zones based on intraflow structures observed in the field and primary igneous textures observed in thin section. These zones include, from the base upward, the flow interior, transition, and flow-top breccia zones of the analog flow, the interflow contact zone, and the flow interior and flow-top breccia zone of the superjacent flow. The intraflow structures and textures of the transition and interflow contact zones are atypical of Grande Ronde Basalt flows. The transition zone is transitional in textures between the flow interior zone and flow-top breccia zone, and includes holocrystalline spines mantled with fused in situ breccias. The interflow contact zone reflects the dynamic interaction during the emplacement of the superjacent flow manifested as invasive basalt tongues, clasts shed from tongues, pipe vesicles and tree molds, and pockets of breccia caught up in the base of the superjacent flow. Close

• 5. [Article] Contributions to Tualatin Ethnography: Subsistence and Ethnobiology

  There is a considerable amount of unpublished source material on Kalapuyan ethnography. This consists primarily of manuscript field notes from three linguistically trained scholars: Albert S. Gatschet, ...

  Citation × Citation Citation Abstract Copy Title: Contributions to Tualatin Ethnography: Subsistence and Ethnobiology Author: Zenk, Henry B. Year: 1976 There is a considerable amount of unpublished source material on Kalapuyan ethnography. This consists primarily of manuscript field notes from three linguistically trained scholars: Albert S. Gatschet, who collected Kalapuyan linguistic and ethnographic data during a visit to Grand Ronde Reservation in 1877, Leo J. Frachtenberg, who worked with a number of Kalapuyan informants from 1913 to 1915, and Melville Jacobs, who worked with the last surviving speakers of Kalapuyan languages during a number of sessions between 1928 and 1936. Data from these three authorities, plus other available data, reveal many details about aboriginal Kalapuyan life (“aboriginal” here referring to the period from around first White contact until removal to the reservation). Any attempt to reconstruct ethnographic descriptions of the aboriginal Kalapuyans should fully utilize these available data. I intend this thesis as a beginning effort toward that end. It seemed to me that the ethnographic notes scattered through the Gatschet manuscripts, representing as they do the knowledge of informants who had reached adulthood under pre-reservation conditions, would prove particularly interesting in terms of ethnographic reconstruction. Thus, I selected the Tualatin Kalapuyans, the subject of Gatschet’s main effort, as my own focus. In view of the quantity of data involved, I further restricted my scope to much less than an overall ethnographic description of the aboriginal Tualatin. I have concentrated upon two related aspects of that larger picture -- subsistence and ethnobiology. Under the former, I consider aboriginal habitat, general subsistence economy, territorial and seasonal availability of subsistence resources, seasonal cycles involved in harvest of resources, subsistence-related aspects of regional interrelationships such as trade, and specific subsistence-related activities and practices. Under ethnobiology, I consider native knowledge and uses of plant and animal resources. In Chapter IV, some additional ethnographic information unrelated to these two main areas is also presented concerning the identification and localization of Tualatin winter-village groups. Title: Contributions to Tualatin Ethnography: Subsistence and Ethnobiology Author: Zenk, Henry B. Year: 1976 There is a considerable amount of unpublished source material on Kalapuyan ethnography. This consists primarily of manuscript field notes from three linguistically trained scholars: Albert S. Gatschet, who collected Kalapuyan linguistic and ethnographic data during a visit to Grand Ronde Reservation in 1877, Leo J. Frachtenberg, who worked with a number of Kalapuyan informants from 1913 to 1915, and Melville Jacobs, who worked with the last surviving speakers of Kalapuyan languages during a number of sessions between 1928 and 1936. Data from these three authorities, plus other available data, reveal many details about aboriginal Kalapuyan life (“aboriginal” here referring to the period from around first White contact until removal to the reservation). Any attempt to reconstruct ethnographic descriptions of the aboriginal Kalapuyans should fully utilize these available data. I intend this thesis as a beginning effort toward that end. It seemed to me that the ethnographic notes scattered through the Gatschet manuscripts, representing as they do the knowledge of informants who had reached adulthood under pre-reservation conditions, would prove particularly interesting in terms of ethnographic reconstruction. Thus, I selected the Tualatin Kalapuyans, the subject of Gatschet’s main effort, as my own focus. In view of the quantity of data involved, I further restricted my scope to much less than an overall ethnographic description of the aboriginal Tualatin. I have concentrated upon two related aspects of that larger picture -- subsistence and ethnobiology. Under the former, I consider aboriginal habitat, general subsistence economy, territorial and seasonal availability of subsistence resources, seasonal cycles involved in harvest of resources, subsistence-related aspects of regional interrelationships such as trade, and specific subsistence-related activities and practices. Under ethnobiology, I consider native knowledge and uses of plant and animal resources. In Chapter IV, some additional ethnographic information unrelated to these two main areas is also presented concerning the identification and localization of Tualatin winter-village groups. Close

• 6. [Article] The stratigraphy and structure of the Columbia River basalt group in the Bull Run watershed, Multnomah and Clackamas Counties, Oregon

  Approximately 150 meters (500 feet) of Grande Ronde Basalt and 140 meters (450 feet) of Wanapum Basalt of the Columbia River Basalt Group are exposed in the Bull Run Watershed. In Bull Run, the Grande ...

  Citation × Citation Citation Abstract Copy Title: The stratigraphy and structure of the Columbia River basalt group in the Bull Run watershed, Multnomah and Clackamas Counties, Oregon Author: Vogt, Beverly Frobenius Year: 1981 Approximately 150 meters (500 feet) of Grande Ronde Basalt and 140 meters (450 feet) of Wanapum Basalt of the Columbia River Basalt Group are exposed in the Bull Run Watershed. In Bull Run, the Grande Ronde Basalt is divided into three mappable units: "low Mg" R2 (at least one flow), "low Mg" N2 (approximately four flows), and "high Mg" N2 (two to three flows}. The Wanapum Basalt is represented by two members: Frenchman Springs Member (six flows) and Priest Rapids Member (one flow). These units are identified by instrumental neutron activation analysis, paleomagnetism based on measurements with a fluxgate magnetometer, petrography, lithology, jointing, and stratigraphic position. Title: The stratigraphy and structure of the Columbia River basalt group in the Bull Run watershed, Multnomah and Clackamas Counties, Oregon Author: Vogt, Beverly Frobenius Year: 1981 Approximately 150 meters (500 feet) of Grande Ronde Basalt and 140 meters (450 feet) of Wanapum Basalt of the Columbia River Basalt Group are exposed in the Bull Run Watershed. In Bull Run, the Grande Ronde Basalt is divided into three mappable units: "low Mg" R2 (at least one flow), "low Mg" N2 (approximately four flows), and "high Mg" N2 (two to three flows}. The Wanapum Basalt is represented by two members: Frenchman Springs Member (six flows) and Priest Rapids Member (one flow). These units are identified by instrumental neutron activation analysis, paleomagnetism based on measurements with a fluxgate magnetometer, petrography, lithology, jointing, and stratigraphic position. Close

• 7. [Article] The Siletz Indian Reservation, 1855-1900

  The aim of my study was to try to bring forth the basic aspects and characteristics of the Siletz Reservation as it was in the nineteenth century. Concentration was placed on the life activities and concerns ...

  Citation × Citation Citation Abstract Copy Title: The Siletz Indian Reservation, 1855-1900 Author: Kent, William Eugene Year: 1973 The aim of my study was to try to bring forth the basic aspects and characteristics of the Siletz Reservation as it was in the nineteenth century. Concentration was placed on the life activities and concerns of a typical resident, while at the same time extremes in behavior and actions were also noted. Thus an entire spectrum of human life was recreated. Government policies and events and changes of the time were noted as to how they affected the life at the reservation. I did not include all of the information available to me .and all information is not known by any single authority or source of information. I feel that I have presented a broad and, satisfactory picture of my topic. It is hoped that someday more information and insight will be presented that will add depth to my initial study. Also out of necessity I could only briefly cover many topics which could easily be worthwhile covering in more detail. Thus there is more ground to cover. Despite its importance, there is correspondingly not much written about the Siletz Reservation. This is largely probably due to the fact that the reservation fades fast from a center of attention. The population fell below five hundred by the turn of the century, thus making the place far from a population center. A second factor was that the people became a new people in a new world and so, instead of continuing to be a home to change Indians, it was merely a home for people who lived like other Americans but were Indian by heart and appearance. Aside from a few studies and sources of information, there are two main sources of information. The first is the annual reports sent to the Secretary of Interior. These can be found in any major library. The second source is the manuscripts. These are the records and correspondence of the agency. The Siletz Manuscripts are in six boxes at the Oregon Historical Society Library in Portland. The material is unorganized and much of it is damaged. There is also material not related to Siletz. Some of Joel Palmer's Indian Treaties are there as well as quite a lot of records of the Grand Ronde Reservation. Unfortunately, it is largely correspondence to the Agency rather than that sent out. The government archives may have some of the correspondence. As every student and author knows, writing poses many problems. There are any number of ways to put together a study of this kind. I divided mine into three basic parts. The first section is a year by year analysis. The second is topic by topic, and finally the third is again yearly. This helped me keep on the general topic of the reservation itself while still being able to diverge and enlarge on important issues. It was a challenging and rewarding task which I hope will be enjoyed by others and will add to their knowledge and understanding of the Siletz Indians and their life on the Reservation. Title: The Siletz Indian Reservation, 1855-1900 Author: Kent, William Eugene Year: 1973 The aim of my study was to try to bring forth the basic aspects and characteristics of the Siletz Reservation as it was in the nineteenth century. Concentration was placed on the life activities and concerns of a typical resident, while at the same time extremes in behavior and actions were also noted. Thus an entire spectrum of human life was recreated. Government policies and events and changes of the time were noted as to how they affected the life at the reservation. I did not include all of the information available to me .and all information is not known by any single authority or source of information. I feel that I have presented a broad and, satisfactory picture of my topic. It is hoped that someday more information and insight will be presented that will add depth to my initial study. Also out of necessity I could only briefly cover many topics which could easily be worthwhile covering in more detail. Thus there is more ground to cover. Despite its importance, there is correspondingly not much written about the Siletz Reservation. This is largely probably due to the fact that the reservation fades fast from a center of attention. The population fell below five hundred by the turn of the century, thus making the place far from a population center. A second factor was that the people became a new people in a new world and so, instead of continuing to be a home to change Indians, it was merely a home for people who lived like other Americans but were Indian by heart and appearance. Aside from a few studies and sources of information, there are two main sources of information. The first is the annual reports sent to the Secretary of Interior. These can be found in any major library. The second source is the manuscripts. These are the records and correspondence of the agency. The Siletz Manuscripts are in six boxes at the Oregon Historical Society Library in Portland. The material is unorganized and much of it is damaged. There is also material not related to Siletz. Some of Joel Palmer's Indian Treaties are there as well as quite a lot of records of the Grand Ronde Reservation. Unfortunately, it is largely correspondence to the Agency rather than that sent out. The government archives may have some of the correspondence. As every student and author knows, writing poses many problems. There are any number of ways to put together a study of this kind. I divided mine into three basic parts. The first section is a year by year analysis. The second is topic by topic, and finally the third is again yearly. This helped me keep on the general topic of the reservation itself while still being able to diverge and enlarge on important issues. It was a challenging and rewarding task which I hope will be enjoyed by others and will add to their knowledge and understanding of the Siletz Indians and their life on the Reservation. Close

• 8. [Article] Motivation in the Portland Chinuk Wawa language community

  Throughout the world, languages are becoming extinct at an alarming rate. Perhaps half of the 6,000-7,000 languages worldwide will go extinct in the next 50-100 years. One of these dying languages, Chinook ...

  Citation × Citation Citation Abstract Copy Title: Motivation in the Portland Chinuk Wawa language community Author: Pecore, Abigail Elaina Year: 2012 Throughout the world, languages are becoming extinct at an alarming rate. Perhaps half of the 6,000-7,000 languages worldwide will go extinct in the next 50-100 years. One of these dying languages, Chinook Jargon or Chinuk Wawa, a language found in the Pacific Northwest of the United States, is in the process of being revitalized through the concerted efforts of the Confederated Tribes of Grand Ronde (CTGR). Reasons to revitalize endangered languages often seem irrelevant to our modern daily lives, and revitalizing these languages is a difficult process requiring much dedication, commitment, and persistence. In light of this significant struggle, understanding people's motivations could contribute to a better understanding of how to involve more people in language revitalization. Ideally, such an understanding would contribute to strengthening a community's efforts to revitalize their language. This exploratory, ethnographic case study explores the motivations of eight participants in the Portland Chinuk Wawa language community involved in revitalizing Chinuk Wawa over a nine-month period in 2011. The results of the study showed that seven major themes of motivation were prevalent for the participants: connections made through Chinuk Wawa, preservation of Chinuk Wawa, relationships, instrumental motivation, affective motivation, identity motivation, and demotivation. Title: Motivation in the Portland Chinuk Wawa language community Author: Pecore, Abigail Elaina Year: 2012 Throughout the world, languages are becoming extinct at an alarming rate. Perhaps half of the 6,000-7,000 languages worldwide will go extinct in the next 50-100 years. One of these dying languages, Chinook Jargon or Chinuk Wawa, a language found in the Pacific Northwest of the United States, is in the process of being revitalized through the concerted efforts of the Confederated Tribes of Grand Ronde (CTGR). Reasons to revitalize endangered languages often seem irrelevant to our modern daily lives, and revitalizing these languages is a difficult process requiring much dedication, commitment, and persistence. In light of this significant struggle, understanding people's motivations could contribute to a better understanding of how to involve more people in language revitalization. Ideally, such an understanding would contribute to strengthening a community's efforts to revitalize their language. This exploratory, ethnographic case study explores the motivations of eight participants in the Portland Chinuk Wawa language community involved in revitalizing Chinuk Wawa over a nine-month period in 2011. The results of the study showed that seven major themes of motivation were prevalent for the participants: connections made through Chinuk Wawa, preservation of Chinuk Wawa, relationships, instrumental motivation, affective motivation, identity motivation, and demotivation. Close

• 9. [Article] Hydrogeologic Characterization of Dutch Canyon, Scappoose, Oregon

  Dutch Canyon is located directly west of the City of Scappoose in Columbia County Oregon. This area is proximate to Highway 30, a major access corridor to downtown Portland, and is experiencing a population ...

  Citation × Citation Citation Abstract Copy Title: Hydrogeologic Characterization of Dutch Canyon, Scappoose, Oregon Author: Wagner, Derrick Lee Year: 2013 Dutch Canyon is located directly west of the City of Scappoose in Columbia County Oregon. This area is proximate to Highway 30, a major access corridor to downtown Portland, and is experiencing a population increase, which is expected to continue and likely accelerate. As a result, there is growing pressure on water resources. Individual and community efforts to utilize groundwater resources have been hampered by generally poor groundwater yields and water quality concerns outside of the Columbia River corridor and a lack of published hydrogeologic information for the region. The intent of this study is to identify the water-bearing units present in Dutch Canyon and to characterize water quality within these units. The physical hydrogeology of Dutch Canyon was assessed mainly through the collation of 196 local well reports that contained lithologic information from which individual hydrostratigraphic units were identified and characterized. Hydraulic parameters for individual units were estimated using pump rates and drawdowns provided in select well reports. Water quality for the units identified was assessed through the collection of 48 samples of well, spring, and stream water from Dutch Canyon. Measurements of pH, specific conductivity, temperature, dissolved oxygen, reduction potential, and alkalinity were recorded in the field and samples were analyzed for major ions, arsenic, and stable isotopes. The major water-bearing units of Dutch Canyon were separated into five physically distinct hydrostratigrapic units: the lower, middle, and upper units of the sedimentary Lower Miocene Scappoose Formation, and the Wapshilla Ridge and Ortley members of the Lower to Middle Miocene Grande Ronde Basalt. Groundwater flow likely occurs in discrete, relatively thin (~2- to 10-m thick) zones within the Grand Ronde Basalt members. These units only occur along the slopes and ridges of Dutch Canyon west of the Portland Hills Fault, which parallels the eastern margin of the study area. The Scappoose Formation units contain clay- and silt-rich layers and lenses that limit the useable aquifer volume and vertical movement of groundwaters. In general, all hydrostratrigraphic units east of the Portland Hills Fault have low transmissivities and water wells completed in each of them are commonly low- yielding wells, though there are some exceptions. Geochemically, the lower and middle units of the Scappoose Formation were similar to one another with many wells yielding groundwater with high total dissolved solids (TDS) contents (mean TDS = 330 mg L-1; n = 27). Nearly 20% of the wells sampled that were screened in these units (5 of 27) yielded groundwater that exceeded the U.S. Environmental Protection Agency's National Secondary (non-enforceable) Drinking Water Regulation standard of 500 mg L-1 TDS. The upper unit of the Scappoose Formation and the overlying Grande Ronde Basalt members generally yield water with lower TDS contents (mean < 200 mg L-1; maximum = 342 mg L-1; n = 20). Groundwater resources in Dutch Canyon are limited and low well yields are common. The primary water quality concern is saline water, which is generally found in the lower and middle units of the Scappoose Formation near the valley floor. Low recharge rates determined from hydrograph analysis of stream discharge measurements are consistent with the geology and steep terrain of the area and further limit the available groundwater and the degree of flushing of what may be connate waters in the deeper units. Title: Hydrogeologic Characterization of Dutch Canyon, Scappoose, Oregon Author: Wagner, Derrick Lee Year: 2013 Dutch Canyon is located directly west of the City of Scappoose in Columbia County Oregon. This area is proximate to Highway 30, a major access corridor to downtown Portland, and is experiencing a population increase, which is expected to continue and likely accelerate. As a result, there is growing pressure on water resources. Individual and community efforts to utilize groundwater resources have been hampered by generally poor groundwater yields and water quality concerns outside of the Columbia River corridor and a lack of published hydrogeologic information for the region. The intent of this study is to identify the water-bearing units present in Dutch Canyon and to characterize water quality within these units. The physical hydrogeology of Dutch Canyon was assessed mainly through the collation of 196 local well reports that contained lithologic information from which individual hydrostratigraphic units were identified and characterized. Hydraulic parameters for individual units were estimated using pump rates and drawdowns provided in select well reports. Water quality for the units identified was assessed through the collection of 48 samples of well, spring, and stream water from Dutch Canyon. Measurements of pH, specific conductivity, temperature, dissolved oxygen, reduction potential, and alkalinity were recorded in the field and samples were analyzed for major ions, arsenic, and stable isotopes. The major water-bearing units of Dutch Canyon were separated into five physically distinct hydrostratigrapic units: the lower, middle, and upper units of the sedimentary Lower Miocene Scappoose Formation, and the Wapshilla Ridge and Ortley members of the Lower to Middle Miocene Grande Ronde Basalt. Groundwater flow likely occurs in discrete, relatively thin (~2- to 10-m thick) zones within the Grand Ronde Basalt members. These units only occur along the slopes and ridges of Dutch Canyon west of the Portland Hills Fault, which parallels the eastern margin of the study area. The Scappoose Formation units contain clay- and silt-rich layers and lenses that limit the useable aquifer volume and vertical movement of groundwaters. In general, all hydrostratrigraphic units east of the Portland Hills Fault have low transmissivities and water wells completed in each of them are commonly low- yielding wells, though there are some exceptions. Geochemically, the lower and middle units of the Scappoose Formation were similar to one another with many wells yielding groundwater with high total dissolved solids (TDS) contents (mean TDS = 330 mg L-1; n = 27). Nearly 20% of the wells sampled that were screened in these units (5 of 27) yielded groundwater that exceeded the U.S. Environmental Protection Agency's National Secondary (non-enforceable) Drinking Water Regulation standard of 500 mg L-1 TDS. The upper unit of the Scappoose Formation and the overlying Grande Ronde Basalt members generally yield water with lower TDS contents (mean < 200 mg L-1; maximum = 342 mg L-1; n = 20). Groundwater resources in Dutch Canyon are limited and low well yields are common. The primary water quality concern is saline water, which is generally found in the lower and middle units of the Scappoose Formation near the valley floor. Low recharge rates determined from hydrograph analysis of stream discharge measurements are consistent with the geology and steep terrain of the area and further limit the available groundwater and the degree of flushing of what may be connate waters in the deeper units. Close

• 10. [Article] The Littlefield Rhyolite, Eastern Oregon: Distinct Flow Units and Their Constraints on Age and Storage Sites of Grande Ronde Basalt Magmas

  The Littlefield Rhyolite consists of widespread, high-temperature, hotspot-related rhyolitic lavas that erupted in eastern Oregon contemporaneous to late-stage Grande Ronde Basalt lavas. The estimated ...

  Citation × Citation Citation Abstract Copy Title: The Littlefield Rhyolite, Eastern Oregon: Distinct Flow Units and Their Constraints on Age and Storage Sites of Grande Ronde Basalt Magmas Author: Webb, Brian McCulloch Year: 2017 The Littlefield Rhyolite consists of widespread, high-temperature, hotspot-related rhyolitic lavas that erupted in eastern Oregon contemporaneous to late-stage Grande Ronde Basalt lavas. The estimated total volume of erupted rhyolites is ~100 km3 covering ~850 km2. The focus of this study has been to investigate the stratigraphy and petrology of the Littlefield Rhyolite and whether field and geochemical relationships exist to help constrain the timing and storage sites of Grande Ronde Basalt magmas. Although often indistinguishable in the field, our data reveal that the Littlefield Rhyolite consists of two geochemically distinct rhyolite flow packages that are designated here as lower and upper Littlefield Rhyolite, according to stratigraphic relationships in the Malheur River Gorge. Rarely viewed in sequence, these rhyolites are distinguished by Zr, Ba, Nb, TiO2 and FeO contents and 40Ar/39Ar ages (16.12±0.04 and 16.16±0.10 Ma versus 16.01±0.06 and 16.05±0.04 Ma). Rhyolites known either as ‘rhyolite of Cottonwood Mountain’ or ‘rhyolite of Bully Creek Canyon’, and which are exposed around Cottonwood Mountain, northwest of Vale, have compositions similar to samples of lower Littlefield Rhyolite. Additionally, single crystal 40Ar/39Ar ages of two samples (16.12±0.07, 16.20±0.08) are statistically indistinguishable. Among units sandwiched between the lower and upper Littlefield Rhyolite are several lava flows and a one-meter thick agglutinated spatter deposit of Hunter Creek Basalt. The spatter deposit thickens to 10s of meters over a distance of 800 m where the deposit is strongly welded. We recognize this as a venting site of Hunter Creek Basalt, and that Hunter Creek Basalt is geochemically and petrographically similar to, and contemporaneous with, late-stage Grande Ronde Basalt. Ages of Littlefield Rhyolite flow units constrain the timing of eruption of Hunter Creek Basalt to an age span of ~100k years, between 16.05 – 16.12 Ma. One local variant of late-stage Grand Ronde Basalt is icelanditic (~62 wt. % SiO2) and is found at a number of places including a location near the southern extent of the upper Littlefield Rhyolite. Geochemical modeling strongly suggests that icelandite lavas resulted from mixing of Grande Ronde and upper Littlefield Rhyolite magmas, thereby tying a Grande Ronde magma storage site to within the greater Malheur River Gorge area, and indicating contemporaneity of rhyolitic and Grande Ronde magma reservoirs. Title: The Littlefield Rhyolite, Eastern Oregon: Distinct Flow Units and Their Constraints on Age and Storage Sites of Grande Ronde Basalt Magmas Author: Webb, Brian McCulloch Year: 2017 The Littlefield Rhyolite consists of widespread, high-temperature, hotspot-related rhyolitic lavas that erupted in eastern Oregon contemporaneous to late-stage Grande Ronde Basalt lavas. The estimated total volume of erupted rhyolites is ~100 km3 covering ~850 km2. The focus of this study has been to investigate the stratigraphy and petrology of the Littlefield Rhyolite and whether field and geochemical relationships exist to help constrain the timing and storage sites of Grande Ronde Basalt magmas. Although often indistinguishable in the field, our data reveal that the Littlefield Rhyolite consists of two geochemically distinct rhyolite flow packages that are designated here as lower and upper Littlefield Rhyolite, according to stratigraphic relationships in the Malheur River Gorge. Rarely viewed in sequence, these rhyolites are distinguished by Zr, Ba, Nb, TiO2 and FeO contents and 40Ar/39Ar ages (16.12±0.04 and 16.16±0.10 Ma versus 16.01±0.06 and 16.05±0.04 Ma). Rhyolites known either as ‘rhyolite of Cottonwood Mountain’ or ‘rhyolite of Bully Creek Canyon’, and which are exposed around Cottonwood Mountain, northwest of Vale, have compositions similar to samples of lower Littlefield Rhyolite. Additionally, single crystal 40Ar/39Ar ages of two samples (16.12±0.07, 16.20±0.08) are statistically indistinguishable. Among units sandwiched between the lower and upper Littlefield Rhyolite are several lava flows and a one-meter thick agglutinated spatter deposit of Hunter Creek Basalt. The spatter deposit thickens to 10s of meters over a distance of 800 m where the deposit is strongly welded. We recognize this as a venting site of Hunter Creek Basalt, and that Hunter Creek Basalt is geochemically and petrographically similar to, and contemporaneous with, late-stage Grande Ronde Basalt. Ages of Littlefield Rhyolite flow units constrain the timing of eruption of Hunter Creek Basalt to an age span of ~100k years, between 16.05 – 16.12 Ma. One local variant of late-stage Grand Ronde Basalt is icelanditic (~62 wt. % SiO2) and is found at a number of places including a location near the southern extent of the upper Littlefield Rhyolite. Geochemical modeling strongly suggests that icelandite lavas resulted from mixing of Grande Ronde and upper Littlefield Rhyolite magmas, thereby tying a Grande Ronde magma storage site to within the greater Malheur River Gorge area, and indicating contemporaneity of rhyolitic and Grande Ronde magma reservoirs. Close