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• 81. [Article] Benthic foraminifer stable isotope record from Site 849 (0 - 5 Ma) : local and global climate changes

  Benthic foraminifer and δ¹³C data from Site 849, on the west flank of the East Pacific Rise (0°11'N, 110°3l'W; 3851 m), give relatively continuous records of deep Pacific Ocean stable isotope variations ...

  Citation × Citation Citation Abstract Copy Title: Benthic foraminifer stable isotope record from Site 849 (0 - 5 Ma) : local and global climate changes Author: Rugh, W., Morey, A., Hagelberg, T. K., Mix, Alan C., Wilson, J., Pisias, Nicklas G. Benthic foraminifer and δ¹³C data from Site 849, on the west flank of the East Pacific Rise (0°11'N, 110°3l'W; 3851 m), give relatively continuous records of deep Pacific Ocean stable isotope variations between 0 and 5 Ma. The mean sample spacing is 4 k.y. Most analyses are from Cibicides wuellerstorfi> but isotopic offsets relative to Uvigerina peregrina appear roughly constant. Because of its location west of the East Pacific Rise, Site 849 yields a suitable record of mean Pacific Ocean δ¹³C, which approximates a global oceanic signal. The ~lOO-k.y.-period climate cycle, which is prevalent in δ¹⁸O does not dominate the long-term δ¹³C record. For δ¹³C, variations in the -400- and 41-k.y. periods are more important. Phase lags of δ¹³C relative to ice volume in the 41- and 23-k.y. bands are consistent with δ¹³C as a measure of organic biomass. A model-calculated exponential response time of 1-2 k.y. is appropriate for carbon stored in soils and shallow sediments responding to glacial-interglacial climate change. Oceanic δ¹³C leads ice volume slightly in the 100-k.y. band, and this suggests another process such as changes in continental weathering to modulate mean river δ¹³C at long periods. The δ¹³C record from Site 849 diverges from that of Site 677 in the Panama Basin mostly because of decay of ¹³C-depleted organic carbon in the relatively isolated Panama Basin. North Atlantic to Pacific δ¹³C differences calculated using published data from Sites 607 and 849 reveal variations in Pliocene deep water within the range of those of the late Quaternary. Maximum δ¹³C contrast between these sites, which presumably reflects maximum influx of high-δ¹³C northern source water into the deep North Atlantic Ocean, occurred between 1.3 and 2.1 Ma, well after the initiation of Northern Hemisphere glaciation. Export of high-δ¹³C North Atlantic Deep Water from the Atlantic to the circumpolar Antarctic, as recorded by published δ'3C data from Subantarctic Site 704, appears unrelated to the North Atlantic-Pacific δ¹³C contrast. To account for this observation, we suggest that deep-water formation in the North Atlantic reflects northern source characteristics, whereas export of this water into the circumpolar Antarctic reflects Southern Hemisphere wind forcing. Neither process appears directly linked to ice-volume variations. Title: Benthic foraminifer stable isotope record from Site 849 (0 - 5 Ma) : local and global climate changes Author: Rugh, W., Morey, A., Hagelberg, T. K., Mix, Alan C., Wilson, J., Pisias, Nicklas G. Benthic foraminifer and δ¹³C data from Site 849, on the west flank of the East Pacific Rise (0°11'N, 110°3l'W; 3851 m), give relatively continuous records of deep Pacific Ocean stable isotope variations between 0 and 5 Ma. The mean sample spacing is 4 k.y. Most analyses are from Cibicides wuellerstorfi> but isotopic offsets relative to Uvigerina peregrina appear roughly constant. Because of its location west of the East Pacific Rise, Site 849 yields a suitable record of mean Pacific Ocean δ¹³C, which approximates a global oceanic signal. The ~lOO-k.y.-period climate cycle, which is prevalent in δ¹⁸O does not dominate the long-term δ¹³C record. For δ¹³C, variations in the -400- and 41-k.y. periods are more important. Phase lags of δ¹³C relative to ice volume in the 41- and 23-k.y. bands are consistent with δ¹³C as a measure of organic biomass. A model-calculated exponential response time of 1-2 k.y. is appropriate for carbon stored in soils and shallow sediments responding to glacial-interglacial climate change. Oceanic δ¹³C leads ice volume slightly in the 100-k.y. band, and this suggests another process such as changes in continental weathering to modulate mean river δ¹³C at long periods. The δ¹³C record from Site 849 diverges from that of Site 677 in the Panama Basin mostly because of decay of ¹³C-depleted organic carbon in the relatively isolated Panama Basin. North Atlantic to Pacific δ¹³C differences calculated using published data from Sites 607 and 849 reveal variations in Pliocene deep water within the range of those of the late Quaternary. Maximum δ¹³C contrast between these sites, which presumably reflects maximum influx of high-δ¹³C northern source water into the deep North Atlantic Ocean, occurred between 1.3 and 2.1 Ma, well after the initiation of Northern Hemisphere glaciation. Export of high-δ¹³C North Atlantic Deep Water from the Atlantic to the circumpolar Antarctic, as recorded by published δ'3C data from Subantarctic Site 704, appears unrelated to the North Atlantic-Pacific δ¹³C contrast. To account for this observation, we suggest that deep-water formation in the North Atlantic reflects northern source characteristics, whereas export of this water into the circumpolar Antarctic reflects Southern Hemisphere wind forcing. Neither process appears directly linked to ice-volume variations. Close

• 82. [Article] Systematics of the salamander genus Dicamptodon strauch (Amphibia:Caudata:Ambystomatidae)

  Dicamptodon is the single, extant genus of the ambystomatid subfamily Dicamptodontinae. Two species, D. ensatus (Eschscholtz) and D. copei Nussbaum are recognized. D. ensatus is found in the forested, ...

  Citation × Citation Citation Abstract Copy Title: Systematics of the salamander genus Dicamptodon strauch (Amphibia:Caudata:Ambystomatidae) Author: Nussbaum, Ronald A. Dicamptodon is the single, extant genus of the ambystomatid subfamily Dicamptodontinae. Two species, D. ensatus (Eschscholtz) and D. copei Nussbaum are recognized. D. ensatus is found in the forested, mountain regions of northwestern California and western Oregon, in the Willapa Hills and Cascade Mountains of Washington, in extreme southwestern British Columbia, and in the northern and central Rocky Mountains of Idaho. D. copei is found in the Olympic Mountains, Willapa Hills and southwestern Cascades of Washington; and in the vicinity of the Columbia River Gorge in extreme northwestern Oregon. The two species are sympatric in the Columbia River Gorge, southern Willapa Hills, and southwestern Cascades of Washington. The two species differ, among other characters, in blood serum proteins, sensitivity to thyroxine, mode of life history, body size, relative head size, limb length, tail height, tooth number, gill raker number, color, and degree of ossification of skeletal elements. Geographic variation is prominent in D. ensatus. Multivariate analysis of morphometric characters of larval populations discriminates three groups: a Rocky Mountain Group, a Cascade and Oregon Coast Range Group, and a Californian Group. The first two groups seem to be more similar to each other than either is to the Californian Group. The Californian Group can be divided into a southern subgroup and a northern subgroup; and the northern subgroup can be further separated into a coastal subgroup and an interior highlands subgroup. These groups are all more-or-less verified by analysis of color of larvae and adults, and morphometric characters of adults. These groups correspond geographically with major features of topography in the Pacific Northwest. The California Group is confined south of the geologically old and complex Klamath-Siskiyou Mountains. The southern Californian subgroup is found south of the "North Coast Divide", and the northern subgroup is found north of this Divide in an area of northwestern drainage. The interior highlands subgroup of the northern Californian subgroup is found in the higher, summer-dry mountains of northern California where the substrate is complex and of a different origin than the coastal substrate. Strong morphoclines occur across the Klamath-Siskiyou Region into southwestern Oregon. The Rocky Mountain Group is separated from the Cascade and Oregon Coast Range Group by the broad, arid Columbia Plateau. Variation is slight over the relatively small range of D. copei, and what variation exists seems to be a function of geographic distance. The dicamptodontines have been an evolutionarily conservative group confined to the humid temperate, Arcto-Tertiary environments of western North America throughout their Cretaceous and Tertiary history. A remnant of the once wide-spread, ancestral habitat occurs today in the humid fog belt of northwestern California and southwestern Oregon. D. ensatus living in this area today exhibit the most primitive features of all living Dicamptodon. These include: large heads, long limbs and tails, many teeth and gill rakers, propensity to transform, and perhaps the habit of vocalizing as a terrestrial, defensive adaptation. D. copei is viewed as a relatively recent derivitive of an ensatus-like ancestor. This ancestor is believed to have had a propensity for neoteny and body attenuation associated with life in the extreme climatic, physical, and biotic environments imposed by Pleistocene glaciation. Isolation in western Washington during a glacial maximum allowed these tendencies, along with small body size, to be selected for, unhampered by gene flow from outside populations. It is thought that the ensatus-like ancestor of D. copei was more similar to recent northern populations of D. ensatus than to recent Californian populations of D. ensatus. Californian populations were relatively unaffected by Pleistocene climatic extremes, as they passed this period in the milder, ancestral environment of southern, coastal latitudes. During the last glacial maximum, the Rocky Mountain populations were probably continuous with populations on the lower eastern slopes of the Washington Cascades, via a connecting, wet, forested parkland, which existed south of the Cordilleran ice sheet in north-central Washington. This parkland was broken up after the ice retreated, during the Altithermal interval, about 7-4,000 years ago, and it was at this time that the Rocky Mountain Group became isolated. Postglacial readjustments in the ranges of D. copei and D. ensatus account for their current narrow zone of sympatry. Subspecies of D. ensatus and D. copei are not recognized. Title: Systematics of the salamander genus Dicamptodon strauch (Amphibia:Caudata:Ambystomatidae) Author: Nussbaum, Ronald A. Dicamptodon is the single, extant genus of the ambystomatid subfamily Dicamptodontinae. Two species, D. ensatus (Eschscholtz) and D. copei Nussbaum are recognized. D. ensatus is found in the forested, mountain regions of northwestern California and western Oregon, in the Willapa Hills and Cascade Mountains of Washington, in extreme southwestern British Columbia, and in the northern and central Rocky Mountains of Idaho. D. copei is found in the Olympic Mountains, Willapa Hills and southwestern Cascades of Washington; and in the vicinity of the Columbia River Gorge in extreme northwestern Oregon. The two species are sympatric in the Columbia River Gorge, southern Willapa Hills, and southwestern Cascades of Washington. The two species differ, among other characters, in blood serum proteins, sensitivity to thyroxine, mode of life history, body size, relative head size, limb length, tail height, tooth number, gill raker number, color, and degree of ossification of skeletal elements. Geographic variation is prominent in D. ensatus. Multivariate analysis of morphometric characters of larval populations discriminates three groups: a Rocky Mountain Group, a Cascade and Oregon Coast Range Group, and a Californian Group. The first two groups seem to be more similar to each other than either is to the Californian Group. The Californian Group can be divided into a southern subgroup and a northern subgroup; and the northern subgroup can be further separated into a coastal subgroup and an interior highlands subgroup. These groups are all more-or-less verified by analysis of color of larvae and adults, and morphometric characters of adults. These groups correspond geographically with major features of topography in the Pacific Northwest. The California Group is confined south of the geologically old and complex Klamath-Siskiyou Mountains. The southern Californian subgroup is found south of the "North Coast Divide", and the northern subgroup is found north of this Divide in an area of northwestern drainage. The interior highlands subgroup of the northern Californian subgroup is found in the higher, summer-dry mountains of northern California where the substrate is complex and of a different origin than the coastal substrate. Strong morphoclines occur across the Klamath-Siskiyou Region into southwestern Oregon. The Rocky Mountain Group is separated from the Cascade and Oregon Coast Range Group by the broad, arid Columbia Plateau. Variation is slight over the relatively small range of D. copei, and what variation exists seems to be a function of geographic distance. The dicamptodontines have been an evolutionarily conservative group confined to the humid temperate, Arcto-Tertiary environments of western North America throughout their Cretaceous and Tertiary history. A remnant of the once wide-spread, ancestral habitat occurs today in the humid fog belt of northwestern California and southwestern Oregon. D. ensatus living in this area today exhibit the most primitive features of all living Dicamptodon. These include: large heads, long limbs and tails, many teeth and gill rakers, propensity to transform, and perhaps the habit of vocalizing as a terrestrial, defensive adaptation. D. copei is viewed as a relatively recent derivitive of an ensatus-like ancestor. This ancestor is believed to have had a propensity for neoteny and body attenuation associated with life in the extreme climatic, physical, and biotic environments imposed by Pleistocene glaciation. Isolation in western Washington during a glacial maximum allowed these tendencies, along with small body size, to be selected for, unhampered by gene flow from outside populations. It is thought that the ensatus-like ancestor of D. copei was more similar to recent northern populations of D. ensatus than to recent Californian populations of D. ensatus. Californian populations were relatively unaffected by Pleistocene climatic extremes, as they passed this period in the milder, ancestral environment of southern, coastal latitudes. During the last glacial maximum, the Rocky Mountain populations were probably continuous with populations on the lower eastern slopes of the Washington Cascades, via a connecting, wet, forested parkland, which existed south of the Cordilleran ice sheet in north-central Washington. This parkland was broken up after the ice retreated, during the Altithermal interval, about 7-4,000 years ago, and it was at this time that the Rocky Mountain Group became isolated. Postglacial readjustments in the ranges of D. copei and D. ensatus account for their current narrow zone of sympatry. Subspecies of D. ensatus and D. copei are not recognized. Close

• 83. [Article] Patterns of tree establishment and vegetation composition in relation to climate and topography of a subalpine meadow landscape, Jefferson Park, Oregon, USA

  The forest alpine tundra ecotone (FTE, also known as alpine treeline or subalpine parkland), is a conspicuous feature of mountain landscapes throughout the world. Climate change-driven increases in temperature ...

  Citation × Citation Citation Abstract Copy Title: Patterns of tree establishment and vegetation composition in relation to climate and topography of a subalpine meadow landscape, Jefferson Park, Oregon, USA Author: Zald, Harold Samuel James The forest alpine tundra ecotone (FTE, also known as alpine treeline or subalpine parkland), is a conspicuous feature of mountain landscapes throughout the world. Climate change-driven increases in temperature are believed to result in FTE movement and tree invasion of subalpine meadows, which have been documented throughout the Northern Hemisphere across a wide range of geographic locations, climatic regimes, forest types, land use histories, and disturbance regimes. Climate-driven FTE movement may have numerous ecological effects such as: positive temperature feedbacks, increased net primary productivity and carbon storage, and declines of plant populations and species. The magnitude of these ecological effects is highly uncertain, but will be largely determined by the rates and spatial extent of FTE movement and meadow invasion. FTE movement and meadow invasion are often considered at global or regional spatial scales in relation to climate, yet they are fundamentally driven by tree regeneration processes that are influenced by a variety of climatic and biophysical factors at micro site, landscape, and regional scales. Much of the research on the FTE has not taken a landscape approach incorporating multi-scale processes. For example, species distribution models used to project climate change effects on future species distributions and plant biodiversity in mountainous landscapes rely on species distribution data that is often sparse and incomplete across FTE landscapes. This dissertation attempts to overcome many of the limitations in FTE research by taking a landscape approach to develop a greater understanding of past spatiotemporal patterns of tree invasion, current spatial patterns of vegetation composition and structure, and potential future patterns of climate-driven tree invasion in the FTE. The setting for this research is Jefferson Park, a 260 ha subalpine parkland landscape in the Oregon High Cascades, USA. This study uses field plots, remotely sensed imagery, airborne Light Detection and Ranging (LiDAR), and simulation modeling to: 1) predictively map current fine-scale species distributions, vegetation structure, and tree ages; 2) reconstruct patterns of tree invasion over the last fifty years in subalpine meadows in relation to climatic conditions, landforms, microtopography, and seed dispersal limitations; and 3) develop a statistical model that projects future patterns of tree invasion into subalpine meadows under different climate scenarios in Jefferson Park. In chapter two, I generated fine-scale spatially-explicit predictions of current vegetation composition, structure, and tree ages in the Jefferson Park study area. Objectives of this chapter were threefold: 1) to characterize spatial patterns of tree ages, vegetation composition, and vegetation structure in a FTE landscape in the Oregon Cascades using predictive mapping; 2) determine how vegetation composition and structure were associated with gradients of environmental factors derived from multispectral satellite imagery and Light Detection and Ranging (LiDAR) data; and 3) determine if predictive mapping characterizations of tree age, vegetation composition, and vegetation structure were improved by the inclusion of LiDAR data. Predictive mapping of vegetation attributes was accomplished using gradient analysis with nearest neighbor imputation; integrating field plots, multispectral SPOT 5 satellite imagery, and LiDAR data. Vegetation composition was best described by SPOT 5 imagery and LiDAR-derived topography, while vegetation structure was best described by LiDAR-derived vegetation heights. Predictions of species occurrence were most accurate for tree species, moderate for shrub species and vegetation groups, and highly variable for graminoid species. Tree age, which was the most accurately predicted vegetation structure variable, indicates the study area was largely un-forested in 1600, gradually invaded by trees from 1600 to the 1920's, and rapidly invaded from the 1920's to 1980. Predictive mapping of vegetation structure variables such as basal area and stand density were subject to large amounts of error, possibly resulting from scale incompatibilities between vegetation patterns and plot size, and/or heterogeneous FTE landscapes where forest structure does not develop along consistent trajectories with stand age. This study suggests integrating multispectral satellite imagery, LiDAR data, and field plots can accurately predict fine-scale spatial characterizations of species distributions and tree invasion in the FTE. This study also indicates that sample design can influence spatial patterns of model uncertainty, which needs to be considered if predictive mapping of vegetation and sensitive ecosystems is a component of inventory and monitoring programs. In chapter three, I focused on quantifying spatiotemporal patterns of subalpine parkland tree invasion in Jefferson Park over the past five decades in relation multi-scale climatic and biophysical controls. LiDAR data provided previously unavailable fine-scale spatial characterizations of microtopography and vegetation structure. I utilized LiDAR, georeferenced field plots, and tree establishment reconstructions to quantify spatiotemporal patterns of tree invasion in relation to late season snow persistence, landform types, fine-scale topographic variability, distances from potential seed sources, and climate variation within 130 ha of the subalpine parkland landscape of Jefferson Park. Tree occurrence (i.e. tree presence in 2 m plots and grid cells) occurred in 7.75% of study area meadows in 1950 and increased to 34.7% in 2007. Landform types and finer-scale patterns of topography and vegetation structure influenced summer snow depth, which influenced temporal and spatial patterns of tree establishment. Tree invasion rates were higher on debris flow landforms, which had lower summer snow depth than glacial landforms, suggesting potentially rapid treeline responses to disturbance events. Tree invasion rates were strongly associated with reduced annual snow fall on glacial landforms, but not on debris flows. Tree establishment was spatially constrained to micro sites with high topographic positions and close proximity to overstory canopy, site conditions associated with low summer snow depth. Seed source limitations placed an additional species-specific spatial constraint on where trees invaded meadows. Climate and topography had an interactive effect, with trees establishing on higher topographic positions during both high snow/low temperature and low snow/high temperature periods, but had greater than expected establishment on lower topographic positions during low snow/high temperature periods. Within the context of larger landform types, topography and proximity to overstory trees constrained where trees established in the meadows, even during climate periods with higher temperatures and lower snowfall. Results of this study suggest large scale climate-driven models of vegetation change may overestimate treeline movement and meadow invasion, because they do not account for biophysical controls limiting tree establishment at multiple spatial scales. In chapter four, I used field data and analyses from chapter 3 to parameterize a spatially and temporally explicit statistical model of fine-scale tree invasion within 130 ha of the Jefferson Park study area. The model incorporated both the climatic and biophysical controls found in chapter 3 to influence tree invasion. The model was used in two ways: (1) to spatially project patterns of tree invasion from 1950 to 2007 in response to historical climate; and (2) to project future tree invasion of the study area from 2007 to 2064 under six different annual snowfall scenarios. Modeling addressed the following questions: (1) Can fine-scale (2 m pixel size) patterns of historical tree invasion be accurately predicted? (2) How sensitive is future tree invasion (and therefore meadow persistence) to different future snowfall scenarios? (3) Are non-climatic factors such as landforms and biotic interactions associated with different spatial patterns of tree invasion? From 1950 to 2007, simulated historical meadow area declined from 82% to 65% of the study area. Model outputs of historical area, spatial distributions, and spatial clustering of tree invasion generally agreed with independent validation, and suggest biotic interactions due to young tree establishment facilitation are important on glacial landforms but not debris flows. Simulations of future scenarios indicated meadow declined to 36 to 43% of the study area by 2064. Projected meadow area declined with reduced annual snow fall, but not under prolonged high and low snow fall periods. Meadows persisted under all future scenarios in 2064. This model suggests subalpine meadows may significantly decline under climate warming, but will still persist in 2064. Micro sites and recruitment limitation may be equally or more important factors than climate change in influencing subalpine landscape change, suggesting local high-elevation persistence of subalpine meadows under future climate warming. Title: Patterns of tree establishment and vegetation composition in relation to climate and topography of a subalpine meadow landscape, Jefferson Park, Oregon, USA Author: Zald, Harold Samuel James The forest alpine tundra ecotone (FTE, also known as alpine treeline or subalpine parkland), is a conspicuous feature of mountain landscapes throughout the world. Climate change-driven increases in temperature are believed to result in FTE movement and tree invasion of subalpine meadows, which have been documented throughout the Northern Hemisphere across a wide range of geographic locations, climatic regimes, forest types, land use histories, and disturbance regimes. Climate-driven FTE movement may have numerous ecological effects such as: positive temperature feedbacks, increased net primary productivity and carbon storage, and declines of plant populations and species. The magnitude of these ecological effects is highly uncertain, but will be largely determined by the rates and spatial extent of FTE movement and meadow invasion. FTE movement and meadow invasion are often considered at global or regional spatial scales in relation to climate, yet they are fundamentally driven by tree regeneration processes that are influenced by a variety of climatic and biophysical factors at micro site, landscape, and regional scales. Much of the research on the FTE has not taken a landscape approach incorporating multi-scale processes. For example, species distribution models used to project climate change effects on future species distributions and plant biodiversity in mountainous landscapes rely on species distribution data that is often sparse and incomplete across FTE landscapes. This dissertation attempts to overcome many of the limitations in FTE research by taking a landscape approach to develop a greater understanding of past spatiotemporal patterns of tree invasion, current spatial patterns of vegetation composition and structure, and potential future patterns of climate-driven tree invasion in the FTE. The setting for this research is Jefferson Park, a 260 ha subalpine parkland landscape in the Oregon High Cascades, USA. This study uses field plots, remotely sensed imagery, airborne Light Detection and Ranging (LiDAR), and simulation modeling to: 1) predictively map current fine-scale species distributions, vegetation structure, and tree ages; 2) reconstruct patterns of tree invasion over the last fifty years in subalpine meadows in relation to climatic conditions, landforms, microtopography, and seed dispersal limitations; and 3) develop a statistical model that projects future patterns of tree invasion into subalpine meadows under different climate scenarios in Jefferson Park. In chapter two, I generated fine-scale spatially-explicit predictions of current vegetation composition, structure, and tree ages in the Jefferson Park study area. Objectives of this chapter were threefold: 1) to characterize spatial patterns of tree ages, vegetation composition, and vegetation structure in a FTE landscape in the Oregon Cascades using predictive mapping; 2) determine how vegetation composition and structure were associated with gradients of environmental factors derived from multispectral satellite imagery and Light Detection and Ranging (LiDAR) data; and 3) determine if predictive mapping characterizations of tree age, vegetation composition, and vegetation structure were improved by the inclusion of LiDAR data. Predictive mapping of vegetation attributes was accomplished using gradient analysis with nearest neighbor imputation; integrating field plots, multispectral SPOT 5 satellite imagery, and LiDAR data. Vegetation composition was best described by SPOT 5 imagery and LiDAR-derived topography, while vegetation structure was best described by LiDAR-derived vegetation heights. Predictions of species occurrence were most accurate for tree species, moderate for shrub species and vegetation groups, and highly variable for graminoid species. Tree age, which was the most accurately predicted vegetation structure variable, indicates the study area was largely un-forested in 1600, gradually invaded by trees from 1600 to the 1920's, and rapidly invaded from the 1920's to 1980. Predictive mapping of vegetation structure variables such as basal area and stand density were subject to large amounts of error, possibly resulting from scale incompatibilities between vegetation patterns and plot size, and/or heterogeneous FTE landscapes where forest structure does not develop along consistent trajectories with stand age. This study suggests integrating multispectral satellite imagery, LiDAR data, and field plots can accurately predict fine-scale spatial characterizations of species distributions and tree invasion in the FTE. This study also indicates that sample design can influence spatial patterns of model uncertainty, which needs to be considered if predictive mapping of vegetation and sensitive ecosystems is a component of inventory and monitoring programs. In chapter three, I focused on quantifying spatiotemporal patterns of subalpine parkland tree invasion in Jefferson Park over the past five decades in relation multi-scale climatic and biophysical controls. LiDAR data provided previously unavailable fine-scale spatial characterizations of microtopography and vegetation structure. I utilized LiDAR, georeferenced field plots, and tree establishment reconstructions to quantify spatiotemporal patterns of tree invasion in relation to late season snow persistence, landform types, fine-scale topographic variability, distances from potential seed sources, and climate variation within 130 ha of the subalpine parkland landscape of Jefferson Park. Tree occurrence (i.e. tree presence in 2 m plots and grid cells) occurred in 7.75% of study area meadows in 1950 and increased to 34.7% in 2007. Landform types and finer-scale patterns of topography and vegetation structure influenced summer snow depth, which influenced temporal and spatial patterns of tree establishment. Tree invasion rates were higher on debris flow landforms, which had lower summer snow depth than glacial landforms, suggesting potentially rapid treeline responses to disturbance events. Tree invasion rates were strongly associated with reduced annual snow fall on glacial landforms, but not on debris flows. Tree establishment was spatially constrained to micro sites with high topographic positions and close proximity to overstory canopy, site conditions associated with low summer snow depth. Seed source limitations placed an additional species-specific spatial constraint on where trees invaded meadows. Climate and topography had an interactive effect, with trees establishing on higher topographic positions during both high snow/low temperature and low snow/high temperature periods, but had greater than expected establishment on lower topographic positions during low snow/high temperature periods. Within the context of larger landform types, topography and proximity to overstory trees constrained where trees established in the meadows, even during climate periods with higher temperatures and lower snowfall. Results of this study suggest large scale climate-driven models of vegetation change may overestimate treeline movement and meadow invasion, because they do not account for biophysical controls limiting tree establishment at multiple spatial scales. In chapter four, I used field data and analyses from chapter 3 to parameterize a spatially and temporally explicit statistical model of fine-scale tree invasion within 130 ha of the Jefferson Park study area. The model incorporated both the climatic and biophysical controls found in chapter 3 to influence tree invasion. The model was used in two ways: (1) to spatially project patterns of tree invasion from 1950 to 2007 in response to historical climate; and (2) to project future tree invasion of the study area from 2007 to 2064 under six different annual snowfall scenarios. Modeling addressed the following questions: (1) Can fine-scale (2 m pixel size) patterns of historical tree invasion be accurately predicted? (2) How sensitive is future tree invasion (and therefore meadow persistence) to different future snowfall scenarios? (3) Are non-climatic factors such as landforms and biotic interactions associated with different spatial patterns of tree invasion? From 1950 to 2007, simulated historical meadow area declined from 82% to 65% of the study area. Model outputs of historical area, spatial distributions, and spatial clustering of tree invasion generally agreed with independent validation, and suggest biotic interactions due to young tree establishment facilitation are important on glacial landforms but not debris flows. Simulations of future scenarios indicated meadow declined to 36 to 43% of the study area by 2064. Projected meadow area declined with reduced annual snow fall, but not under prolonged high and low snow fall periods. Meadows persisted under all future scenarios in 2064. This model suggests subalpine meadows may significantly decline under climate warming, but will still persist in 2064. Micro sites and recruitment limitation may be equally or more important factors than climate change in influencing subalpine landscape change, suggesting local high-elevation persistence of subalpine meadows under future climate warming. Close

• 84. [Article] Man and the land : an ecological history of fire and grazing on eastern Oregon rangelands

  Ecological and historical information are combined in examining the environmental influence of fire and grazing on rangelands in eastern Oregon through time. Competitive relationships between herbaceous ...

  Citation × Citation Citation Abstract Copy Title: Man and the land : an ecological history of fire and grazing on eastern Oregon rangelands Author: Shinn, Dean Allison Ecological and historical information are combined in examining the environmental influence of fire and grazing on rangelands in eastern Oregon through time. Competitive relationships between herbaceous and woody flora in the northern Great Basin are discussed, focusing broadly on the shrubsteppe regions 'of Franklin and Dyrness (1973) but with special reference to the Artemisia/Agropyron association. Impacts of native and domestic grazing animals and of cultural burning are traced from the distant past into recent history. During the Pleistocene Epoch North America supported a wide diversity of large mammals. Toward the end of the Pleistocene, many of these fauna became extinct, perhaps as a result of post-glacial climatic change, perhaps also under the influence of incoming primitive hunting cultures and their broadcast burning practices. Some question exists about the intensity of native grazing in the northern Great Basin during the last few thousand years. Actual levels of bison populations and the duration of their residence in the study area have not been determined. The character of indigenous vegetations, however, indicates that native grazing was relatively light for an extended period primevally. Twenty-four references to native cultural burning at the time of European contact were found in historical journals. Though the antiquity of these customs is uncertain, an analysis of Native American fire myths demonstrates the depth of native cultural perceptions of the relationship between man and fire, and supports the likelihood that fire was used primevally in the northern Great Basin as it was used by aboriginal peoples elsewhere in North America. With the influx of European culture during the 19th century, misapprehensions about fire among whites distorted the influence of native cultural burning. Exotic flora and fauna were introduced, and ecosystems began to change. Large herds of livestock depleted native herbaceous populations. Early irresponsible burning by whites became associated with declining rangeland resources, and efforts toward total fire suppression became incorporated in developing conservation policies. Native woody flora and exotics began to invade open rangeland communities. Climatic flux during the period of European settlement in the northern Great Basin may have exacerbated the impacts of intensified grazing and elimination of burning. Early photographs of rangelands in east-central Oregon were gathered; their dates range from 1880 to the early 1930's. Sites represented in these pictures were re-photographed in 1976. Photo-set comparisons show expansion of western juniper (Juniperus occidentalis) populations into rangeland ecosystems, demonstrating the consequences of cultural disturbances during the last 150 to 200 years. Title: Man and the land : an ecological history of fire and grazing on eastern Oregon rangelands Author: Shinn, Dean Allison Ecological and historical information are combined in examining the environmental influence of fire and grazing on rangelands in eastern Oregon through time. Competitive relationships between herbaceous and woody flora in the northern Great Basin are discussed, focusing broadly on the shrubsteppe regions 'of Franklin and Dyrness (1973) but with special reference to the Artemisia/Agropyron association. Impacts of native and domestic grazing animals and of cultural burning are traced from the distant past into recent history. During the Pleistocene Epoch North America supported a wide diversity of large mammals. Toward the end of the Pleistocene, many of these fauna became extinct, perhaps as a result of post-glacial climatic change, perhaps also under the influence of incoming primitive hunting cultures and their broadcast burning practices. Some question exists about the intensity of native grazing in the northern Great Basin during the last few thousand years. Actual levels of bison populations and the duration of their residence in the study area have not been determined. The character of indigenous vegetations, however, indicates that native grazing was relatively light for an extended period primevally. Twenty-four references to native cultural burning at the time of European contact were found in historical journals. Though the antiquity of these customs is uncertain, an analysis of Native American fire myths demonstrates the depth of native cultural perceptions of the relationship between man and fire, and supports the likelihood that fire was used primevally in the northern Great Basin as it was used by aboriginal peoples elsewhere in North America. With the influx of European culture during the 19th century, misapprehensions about fire among whites distorted the influence of native cultural burning. Exotic flora and fauna were introduced, and ecosystems began to change. Large herds of livestock depleted native herbaceous populations. Early irresponsible burning by whites became associated with declining rangeland resources, and efforts toward total fire suppression became incorporated in developing conservation policies. Native woody flora and exotics began to invade open rangeland communities. Climatic flux during the period of European settlement in the northern Great Basin may have exacerbated the impacts of intensified grazing and elimination of burning. Early photographs of rangelands in east-central Oregon were gathered; their dates range from 1880 to the early 1930's. Sites represented in these pictures were re-photographed in 1976. Photo-set comparisons show expansion of western juniper (Juniperus occidentalis) populations into rangeland ecosystems, demonstrating the consequences of cultural disturbances during the last 150 to 200 years. Close

• 85. [Article] Ecology of harlequin ducks in Prince William Sound, Alaska, during summer

  Harlequin ducks (Histrionicus histrionicus) were observed during the summers of 1979 and 1980 in Sawmill Bay, northeast Prince William Sound, Alaska. Harlequins were associated with a short, medium gradient, non-glacial ...

  Citation × Citation Citation Abstract Copy Title: Ecology of harlequin ducks in Prince William Sound, Alaska, during summer Author: Dzinbal, Kenneth A. Harlequin ducks (Histrionicus histrionicus) were observed during the summers of 1979 and 1980 in Sawmill Bay, northeast Prince William Sound, Alaska. Harlequins were associated with a short, medium gradient, non-glacial stream (Stellar Creek) also used by salmon. Although harlequins nested along Stellar Creek, they apparently did not establish home ranges there during the prenesting period, and both courtship and copulation occurred in the bay. Pairs were most numerous.in the bay in mid-late May; 15 pairs were recorded in 1979, and 14 pairs were observed in 1980. Laying occurred from about 26 May - 17 June, and hatching took place from 3-15 July. Females lost weight during the incubation period, but gained weight the remainder of the. summer. The non-breeding frequency among females was estimated as 47% in 1979 and 50% in 1980. The application of patagial tags, however, appeared to reduce production. Following nesting, males generally deserted Sawmill Bay for comparatively exposed moulting areas, Females mostly remained in the bay until midlate August. Use of habitats by harlequins varied with time of day, and activity budgets varied with habitat. Paired harlequins during prenesting and laying (10 May - 21 June) spent about 47% of their time near rocks and headlands, and about 26% of their time each in Stellar Creek and in lee (i.e. protected) waters. Unpaired harlequins (22 June - 15 August) were rare in lee waters (<3%); unpaired males spent about 77% of their time on rocks and about 20% of their time in Stellar Creek, while unpaired females spent about 43% and 55% of their time on rocks and in Stellar'Creek, respectively. Harlequins primarily rested on rocks and headlands, while lee waters seemed important mostly for social spacing among pairs. Stellar Creek was the focus of nearly half to practically all of the feeding activity of harlequins. Early in the summer they fed primarily on marine invertebrates in the intertidal delta of the creek, but in July they moved upstream into the spawning beds of the arriving salmon, where they fed predominately on loose, drifting roe. Paired females spent more time feeding (21% vs 13%), but less time resting (41% vs 46%) and interacting (1% vs 3%) than did their mates. Unpaired females spent slightly more time feeding (15% vs 13%) and in locomotion (13% vs 10%), but less time preening (6% vs 3%) than did unpaired males. The large proportion of time harlequins spent resting was tentatively attributed to a strategy of minimizing energy expenditure, versus one of maximizing energy intake. Title: Ecology of harlequin ducks in Prince William Sound, Alaska, during summer Author: Dzinbal, Kenneth A. Harlequin ducks (Histrionicus histrionicus) were observed during the summers of 1979 and 1980 in Sawmill Bay, northeast Prince William Sound, Alaska. Harlequins were associated with a short, medium gradient, non-glacial stream (Stellar Creek) also used by salmon. Although harlequins nested along Stellar Creek, they apparently did not establish home ranges there during the prenesting period, and both courtship and copulation occurred in the bay. Pairs were most numerous.in the bay in mid-late May; 15 pairs were recorded in 1979, and 14 pairs were observed in 1980. Laying occurred from about 26 May - 17 June, and hatching took place from 3-15 July. Females lost weight during the incubation period, but gained weight the remainder of the. summer. The non-breeding frequency among females was estimated as 47% in 1979 and 50% in 1980. The application of patagial tags, however, appeared to reduce production. Following nesting, males generally deserted Sawmill Bay for comparatively exposed moulting areas, Females mostly remained in the bay until midlate August. Use of habitats by harlequins varied with time of day, and activity budgets varied with habitat. Paired harlequins during prenesting and laying (10 May - 21 June) spent about 47% of their time near rocks and headlands, and about 26% of their time each in Stellar Creek and in lee (i.e. protected) waters. Unpaired harlequins (22 June - 15 August) were rare in lee waters (<3%); unpaired males spent about 77% of their time on rocks and about 20% of their time in Stellar Creek, while unpaired females spent about 43% and 55% of their time on rocks and in Stellar'Creek, respectively. Harlequins primarily rested on rocks and headlands, while lee waters seemed important mostly for social spacing among pairs. Stellar Creek was the focus of nearly half to practically all of the feeding activity of harlequins. Early in the summer they fed primarily on marine invertebrates in the intertidal delta of the creek, but in July they moved upstream into the spawning beds of the arriving salmon, where they fed predominately on loose, drifting roe. Paired females spent more time feeding (21% vs 13%), but less time resting (41% vs 46%) and interacting (1% vs 3%) than did their mates. Unpaired females spent slightly more time feeding (15% vs 13%) and in locomotion (13% vs 10%), but less time preening (6% vs 3%) than did unpaired males. The large proportion of time harlequins spent resting was tentatively attributed to a strategy of minimizing energy expenditure, versus one of maximizing energy intake. Close

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

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

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

• 87. [Article] Spatial and Temporal Variability of Glacier Melt in the McMurdo Dry Valleys, Antarctica

  In the McMurdo Dry Valleys, Victoria Land, East Antarctica, melting of glacial ice is the primary source of water to streams, lakes, and associated ecosystems. To better understand meltwater production, ...

  Citation × Citation Citation Abstract Copy Title: Spatial and Temporal Variability of Glacier Melt in the McMurdo Dry Valleys, Antarctica Author: Hoffman, Matthew James Year: 2011 In the McMurdo Dry Valleys, Victoria Land, East Antarctica, melting of glacial ice is the primary source of water to streams, lakes, and associated ecosystems. To better understand meltwater production, three hypotheses are tested: 1) that small changes in the surface energy balance on these glaciers will result in large changes in melt, 2) that subsurface melt does not contribute significantly to runoff, and 3) that melt from 25-m high terminal cliffs is the dominant source of baseflow during cold periods. These hypotheses were investigated using a surface energy balance model applied to the glaciers of Taylor Valley using 14 years of meteorological data and calibrated to ablation measurements. Inclusion of transmission of solar radiation into the ice through a source term in a one-dimensional heat transfer equation was necessary to accurately model summer ablation and ice temperatures. Results showed good correspondence between calculated and measured ablation and ice temperatures over the 14 years using both daily and hourly time steps, but an hourly time step allowed resolution of short duration melt events and melt within the upper 15 cm of the ice. Resolution of short duration melt events was not important for properly resolving seasonal ablation totals. Across the smooth surfaces of the glaciers, ablation was dominated by sublimation and melting was rare. Above freezing air temperatures did not necessarily result in melt, and low wind speed was important for melt initiation. According to the model, subsurface melt between 5 and 15 cm depth was extensive and lasted for up to six weeks in some summers. The model was better able to predict ablation if some subsurface melt was assumed to drain, lowering ice density, consistent with observations of a low density weathering crust that forms over the course of the summer on Dry Valley glaciers. In extreme summers, drainage of subsurface melt may have contributed up to half of the observed surface lowering through reduction of ice density and possibly through collapse of highly weathered ice. When applied spatially, the model successfully predicted proglacial streamflow at seasonal and daily time scales. This was despite omitting a routing scheme, and instead assuming that all melt generated exits the glacier on the same day, suggesting refreezing is not substantial. Including subsurface melt as runoff improved predictions of runoff volume and timing, particularly for the recession of large flood peaks. Because overland flow was rarely observed over much of these glaciers, these model results suggest that runoff may be predominantly transported beneath the surface in a partially melted permeable layer of weathered ice. According to the model, topographic basins, particularly the low albedo basin floors, played a prominent role in runoff production. Smooth glacier surfaces exhibited low melt rates, but were important during high melt conditions due to their large surface area. Estimated runoff contributions from cliffs and cryoconite holes was somewhat smaller than suggested in previous studies. Spatial and temporal variability in albedo due to snow and debris played a dominant role in flow variations between streams and seasons. In general, the model supported the existing assumption that snowmelt is insignificant, but in extreme melt years snowmelt in the accumulation area may contribute significantly to runoff in some locations. Title: Spatial and Temporal Variability of Glacier Melt in the McMurdo Dry Valleys, Antarctica Author: Hoffman, Matthew James Year: 2011 In the McMurdo Dry Valleys, Victoria Land, East Antarctica, melting of glacial ice is the primary source of water to streams, lakes, and associated ecosystems. To better understand meltwater production, three hypotheses are tested: 1) that small changes in the surface energy balance on these glaciers will result in large changes in melt, 2) that subsurface melt does not contribute significantly to runoff, and 3) that melt from 25-m high terminal cliffs is the dominant source of baseflow during cold periods. These hypotheses were investigated using a surface energy balance model applied to the glaciers of Taylor Valley using 14 years of meteorological data and calibrated to ablation measurements. Inclusion of transmission of solar radiation into the ice through a source term in a one-dimensional heat transfer equation was necessary to accurately model summer ablation and ice temperatures. Results showed good correspondence between calculated and measured ablation and ice temperatures over the 14 years using both daily and hourly time steps, but an hourly time step allowed resolution of short duration melt events and melt within the upper 15 cm of the ice. Resolution of short duration melt events was not important for properly resolving seasonal ablation totals. Across the smooth surfaces of the glaciers, ablation was dominated by sublimation and melting was rare. Above freezing air temperatures did not necessarily result in melt, and low wind speed was important for melt initiation. According to the model, subsurface melt between 5 and 15 cm depth was extensive and lasted for up to six weeks in some summers. The model was better able to predict ablation if some subsurface melt was assumed to drain, lowering ice density, consistent with observations of a low density weathering crust that forms over the course of the summer on Dry Valley glaciers. In extreme summers, drainage of subsurface melt may have contributed up to half of the observed surface lowering through reduction of ice density and possibly through collapse of highly weathered ice. When applied spatially, the model successfully predicted proglacial streamflow at seasonal and daily time scales. This was despite omitting a routing scheme, and instead assuming that all melt generated exits the glacier on the same day, suggesting refreezing is not substantial. Including subsurface melt as runoff improved predictions of runoff volume and timing, particularly for the recession of large flood peaks. Because overland flow was rarely observed over much of these glaciers, these model results suggest that runoff may be predominantly transported beneath the surface in a partially melted permeable layer of weathered ice. According to the model, topographic basins, particularly the low albedo basin floors, played a prominent role in runoff production. Smooth glacier surfaces exhibited low melt rates, but were important during high melt conditions due to their large surface area. Estimated runoff contributions from cliffs and cryoconite holes was somewhat smaller than suggested in previous studies. Spatial and temporal variability in albedo due to snow and debris played a dominant role in flow variations between streams and seasons. In general, the model supported the existing assumption that snowmelt is insignificant, but in extreme melt years snowmelt in the accumulation area may contribute significantly to runoff in some locations. Close

• 88. [Article] The geology of part of the Snake River Canyon and adjacent areas in Northeastern Oregon and Western Idaho

  The mapped area lies between the Wallowa Mountains of northeastern Oregon and the Seven Devils Mountains of western Idaho. Part of the Snake River canyon is included. A composite stratigraphic section ...

  Citation × Citation Citation Abstract Copy Title: The geology of part of the Snake River Canyon and adjacent areas in Northeastern Oregon and Western Idaho Author: Vallier, Tracy L. (Tracy Lowell), 1936- The mapped area lies between the Wallowa Mountains of northeastern Oregon and the Seven Devils Mountains of western Idaho. Part of the Snake River canyon is included. A composite stratigraphic section includes at least 30,000 feet of strata. Pre- Tertiary and Tertiary strata are separated by a profound unconformity. Pre -Tertiary layered rocks are mostly Permian and Triassic volcaniclastic and volcanic flow rocks. At least four pre -Tertiary intrusive suites occur. Tertiary rocks are Miocene and Pliocene plateau basalts. Quaternary glacial materials and stream deposits locally mantle the older rocks. Permian ( ?) rocks of the Windy Ridge Formation are the oldest rocks and consist of 2,000 to 3,000 feet of keratophyre, quartz keratophyre, and keratophric pyroclastic rocks. Unconformably ( ?) overlying the Windy Ridge Formation are 8,000 to 10,000 feet of volcaniclastic rocks and minor volcanic flow rocks of the Hunsaker Creek Formation of Middle Permian (Leonardian and Wordian) age. Spilitic flow rocks of the Kleinschmidt Volcanics are interlayered with and in part overlie the Hunsaker Creek Formation and comprise a sequence about 2,000 to 3,000 feet thick. The Paleozoic layered rocks were intruded by the Holbrook - Irondyke intrusives, composed of keratophyre porphyry, quartz keratophyre porphyry, diabase, and gabbro. The Paleozoic rocks were deformed by an orogeny between Middle Permian and Middle Triassic time. Plutonic rocks (Oxbow Complex) of gabbro, quartz diorite, diorite, and albite granite were intruded during Early Triassic (7) time. Movements along the Oxbow -Cuprum shear zone occurred during and after the intrusions. Middle Triassic (Ladinian) spilitic flow rocks and volcaniclastic rocks of the Grassy Ridge Formation overlie the older rocks with angular unconformity. Thicknesses are 3,000 to 4,000 feet in the northeast part of the map area; no rocks of the Grassy Ridge Formation are exposed in the southwest part. The Imnaha Formation of Late Triassic (Karnian) age overlies the Permian strata unconformably near Fish Lake in the western part of the area. The Doyle Creek Formation of Late Triassic (Karnian) age conformably overlies the Grassy Ridge Formation in the Snake River and Imnaha River canyons and may interfinger with the Imnaha Formation east of Fish Lake. The Doyle Creek Formation ranges in thickness from 3,000 to 5,000 feet and includes two members - the Ashby Creek Conglomerate and the Piedmont Point Member. The Martin Bridge Formation, represented by 1,750 feet of Late Triassic (Norian) limestone, conformably overlies the Doyle Creek Formation. At least two intrusive events apparently occurred during the Jurassic Period. The Jurassic ( ?) intrusives, were emplaced before regional metamorphism and consist of hypabyssal dikes and sills of diorite, quartz diorite, and dacite and andesite porphyries. Subsequently, the Upper ( ?) Jurassic intrusives were emplaced during a late stage of regional metamorphism and are represented by small stocks of gabbro, norite, quartz diorite, and gran - odiorite porphyry. A major orogeny during Middle and Late ( ?) Jurassic time deformed the rocks. Regional metamorphism produced mineral assemblages characteristic of the greenschist facies. Columbia River Basalt, 2,000 to 3,000 feet thick, erupted from fissures during late Miocene and early Pliocene time and covered an old erosion surface. Pliocene - Pleistocene uplift, alpine glaciation, and extensive stream erosion are responsible for the present topography. Title: The geology of part of the Snake River Canyon and adjacent areas in Northeastern Oregon and Western Idaho Author: Vallier, Tracy L. (Tracy Lowell), 1936- The mapped area lies between the Wallowa Mountains of northeastern Oregon and the Seven Devils Mountains of western Idaho. Part of the Snake River canyon is included. A composite stratigraphic section includes at least 30,000 feet of strata. Pre- Tertiary and Tertiary strata are separated by a profound unconformity. Pre -Tertiary layered rocks are mostly Permian and Triassic volcaniclastic and volcanic flow rocks. At least four pre -Tertiary intrusive suites occur. Tertiary rocks are Miocene and Pliocene plateau basalts. Quaternary glacial materials and stream deposits locally mantle the older rocks. Permian ( ?) rocks of the Windy Ridge Formation are the oldest rocks and consist of 2,000 to 3,000 feet of keratophyre, quartz keratophyre, and keratophric pyroclastic rocks. Unconformably ( ?) overlying the Windy Ridge Formation are 8,000 to 10,000 feet of volcaniclastic rocks and minor volcanic flow rocks of the Hunsaker Creek Formation of Middle Permian (Leonardian and Wordian) age. Spilitic flow rocks of the Kleinschmidt Volcanics are interlayered with and in part overlie the Hunsaker Creek Formation and comprise a sequence about 2,000 to 3,000 feet thick. The Paleozoic layered rocks were intruded by the Holbrook - Irondyke intrusives, composed of keratophyre porphyry, quartz keratophyre porphyry, diabase, and gabbro. The Paleozoic rocks were deformed by an orogeny between Middle Permian and Middle Triassic time. Plutonic rocks (Oxbow Complex) of gabbro, quartz diorite, diorite, and albite granite were intruded during Early Triassic (7) time. Movements along the Oxbow -Cuprum shear zone occurred during and after the intrusions. Middle Triassic (Ladinian) spilitic flow rocks and volcaniclastic rocks of the Grassy Ridge Formation overlie the older rocks with angular unconformity. Thicknesses are 3,000 to 4,000 feet in the northeast part of the map area; no rocks of the Grassy Ridge Formation are exposed in the southwest part. The Imnaha Formation of Late Triassic (Karnian) age overlies the Permian strata unconformably near Fish Lake in the western part of the area. The Doyle Creek Formation of Late Triassic (Karnian) age conformably overlies the Grassy Ridge Formation in the Snake River and Imnaha River canyons and may interfinger with the Imnaha Formation east of Fish Lake. The Doyle Creek Formation ranges in thickness from 3,000 to 5,000 feet and includes two members - the Ashby Creek Conglomerate and the Piedmont Point Member. The Martin Bridge Formation, represented by 1,750 feet of Late Triassic (Norian) limestone, conformably overlies the Doyle Creek Formation. At least two intrusive events apparently occurred during the Jurassic Period. The Jurassic ( ?) intrusives, were emplaced before regional metamorphism and consist of hypabyssal dikes and sills of diorite, quartz diorite, and dacite and andesite porphyries. Subsequently, the Upper ( ?) Jurassic intrusives were emplaced during a late stage of regional metamorphism and are represented by small stocks of gabbro, norite, quartz diorite, and gran - odiorite porphyry. A major orogeny during Middle and Late ( ?) Jurassic time deformed the rocks. Regional metamorphism produced mineral assemblages characteristic of the greenschist facies. Columbia River Basalt, 2,000 to 3,000 feet thick, erupted from fissures during late Miocene and early Pliocene time and covered an old erosion surface. Pliocene - Pleistocene uplift, alpine glaciation, and extensive stream erosion are responsible for the present topography. Close

• 89. [Article] Application of Paleoenvironmental Data for Testing Climate Models and Understanding Past and Future Climate Variations

  Paleo data-model comparison is the process of comparing output from model simulations of past periods with paleoenvironmental data. It enables us to understand both the paleoclimate mechanism and responses ...

  Citation × Citation Citation Abstract Copy Title: Application of Paleoenvironmental Data for Testing Climate Models and Understanding Past and Future Climate Variations Author: Izumi, Kenji Year: 2014 Paleo data-model comparison is the process of comparing output from model simulations of past periods with paleoenvironmental data. It enables us to understand both the paleoclimate mechanism and responses of the earth environment to the climate and to evaluate how models work. This dissertation has two parts that each involve the development and application of approaches for data-model comparisons. In part 1, which is focused on the understanding of both past and future climatic changes/variations, I compare paleoclimate and historical simulations with future climate projections exploiting the fact that climate-model configurations are exactly the same in the paleo and future simulations in the Coupled Model Intercomparison Project Phase 5. In practice, I investigated large-scale temperature responses (land-ocean contrast, high-latitude amplification, and change in temperature seasonality) in paleo and future simulations, found broadly consistent relationships across the climate states, and validated the responses using modern observations and paleoclimate reconstructions. Furthermore, I examined the possibility that a small set of common mechanisms controls the large-scale temperature responses using a simple energy-balance model to decompose the temperature changes shown in warm and cold climate simulations and found that the clear-sky longwave downward radiation is a key control of the robust responses. In part 2, I applied the equilibrium terrestrial biosphere models, BIOME4 and BIOME5 (developed from BIOME4 herein), for reconstructing paleoclimate. I applied inverse modeling through the iterative forward-modeling (IMIFM) approach that uses the North American vegetation data to infer the mid-Holocene (MH, 6000 years ago) and the Last Glacial Maximum (LGM, 21,000 years ago) climates that control vegetation distributions. The IMIFM approach has the potential to provide more accurate quantitative climate estimates from pollen records than statistical approaches. Reconstructed North American MH and LGM climate anomaly patterns are coherent and consistent between variables and between BIOME4 and BIOME5, and these patterns are also consistent with previous data synthesis. This dissertation includes previously published and unpublished coauthored material. Title: Application of Paleoenvironmental Data for Testing Climate Models and Understanding Past and Future Climate Variations Author: Izumi, Kenji Year: 2014 Paleo data-model comparison is the process of comparing output from model simulations of past periods with paleoenvironmental data. It enables us to understand both the paleoclimate mechanism and responses of the earth environment to the climate and to evaluate how models work. This dissertation has two parts that each involve the development and application of approaches for data-model comparisons. In part 1, which is focused on the understanding of both past and future climatic changes/variations, I compare paleoclimate and historical simulations with future climate projections exploiting the fact that climate-model configurations are exactly the same in the paleo and future simulations in the Coupled Model Intercomparison Project Phase 5. In practice, I investigated large-scale temperature responses (land-ocean contrast, high-latitude amplification, and change in temperature seasonality) in paleo and future simulations, found broadly consistent relationships across the climate states, and validated the responses using modern observations and paleoclimate reconstructions. Furthermore, I examined the possibility that a small set of common mechanisms controls the large-scale temperature responses using a simple energy-balance model to decompose the temperature changes shown in warm and cold climate simulations and found that the clear-sky longwave downward radiation is a key control of the robust responses. In part 2, I applied the equilibrium terrestrial biosphere models, BIOME4 and BIOME5 (developed from BIOME4 herein), for reconstructing paleoclimate. I applied inverse modeling through the iterative forward-modeling (IMIFM) approach that uses the North American vegetation data to infer the mid-Holocene (MH, 6000 years ago) and the Last Glacial Maximum (LGM, 21,000 years ago) climates that control vegetation distributions. The IMIFM approach has the potential to provide more accurate quantitative climate estimates from pollen records than statistical approaches. Reconstructed North American MH and LGM climate anomaly patterns are coherent and consistent between variables and between BIOME4 and BIOME5, and these patterns are also consistent with previous data synthesis. This dissertation includes previously published and unpublished coauthored material. Close

• 90. [Article] The fluvial response to glacial-interglacial climate change in the Pacific Northwest, USA

  This research focuses on the development of new techniques to explore terrestrial-ocean climate linkages along the Pacific Northwest-northeast Pacific Ocean margin. This is done by investigating river ...

  Citation × Citation Citation Abstract Copy Title: The fluvial response to glacial-interglacial climate change in the Pacific Northwest, USA Author: VanLaningham, Sam J. This research focuses on the development of new techniques to explore terrestrial-ocean climate linkages along the Pacific Northwest-northeast Pacific Ocean margin. This is done by investigating river response to climate change and by unraveling this history preserved in continental margin sediments. A significant component of this work centers on developing a 40Ar-39Ar incremental heating method to fingerprint bulk fluvial sediment entering this region. Results show reproducible ages from individual rivers accounting for the majority of sediment delivered offshore. A 40Ar-39Ar detrital mixture model is developed to examine the fidelity of these results and shows that the bulk ages measured from river mouth sediments can be accurate indicators of the average age of feldspars eroded from a given catchment area. The bulk sediment ages are combined with Nd isotopic analyses into a ternary mixing model to better understand the sources of terrigenous material delivered to offshore continental margin sites. Downcore Ar-Nd isotopic compositions can be described by three general river sediment sources proximal to the core site, the Umpqua, Rogue+Klamath, and Eel Rivers, from ~14 ka to Present. Results from the ternary model also suggest that differential contributions of eroded material plays the primary role in provenance changes seen at the core site, rather than sediment transport changes due to ocean circulation. This research culminates in a modeling effort to examine downcore provenance changes. We develop a model that balances basin-averaged 40Ar-39Ar ages (detrital mixtures) of the contributing fluvial basins and predicts the bulk sediment value at the core site. We find that the Upper Klamath Basin (which contained pluvial Lake Modoc during Marine Isotope Stage 2) is the most influential source area that can contribute to younger bulk sediment 40Ar-39Ar ages at the core site, relative to present day values. The Eel River is also shown to have a considerable influence on changes in margin sedimentation. Combinations of increases in the sediment fluxes out of these two basins can describe the 40Ar-39Ar provenance evolution observed at the core site over the 22-14 ka time period. Overall, this new 40Ar-39Ar isotopic technique, together with the Nd isotopic system and the use of detrital mixture modeling show tremendous promise as a multi-faceted strategy to assess erosion and provenance change through the continuous history preserved in fine-grained marine sedimentary records. Title: The fluvial response to glacial-interglacial climate change in the Pacific Northwest, USA Author: VanLaningham, Sam J. This research focuses on the development of new techniques to explore terrestrial-ocean climate linkages along the Pacific Northwest-northeast Pacific Ocean margin. This is done by investigating river response to climate change and by unraveling this history preserved in continental margin sediments. A significant component of this work centers on developing a 40Ar-39Ar incremental heating method to fingerprint bulk fluvial sediment entering this region. Results show reproducible ages from individual rivers accounting for the majority of sediment delivered offshore. A 40Ar-39Ar detrital mixture model is developed to examine the fidelity of these results and shows that the bulk ages measured from river mouth sediments can be accurate indicators of the average age of feldspars eroded from a given catchment area. The bulk sediment ages are combined with Nd isotopic analyses into a ternary mixing model to better understand the sources of terrigenous material delivered to offshore continental margin sites. Downcore Ar-Nd isotopic compositions can be described by three general river sediment sources proximal to the core site, the Umpqua, Rogue+Klamath, and Eel Rivers, from ~14 ka to Present. Results from the ternary model also suggest that differential contributions of eroded material plays the primary role in provenance changes seen at the core site, rather than sediment transport changes due to ocean circulation. This research culminates in a modeling effort to examine downcore provenance changes. We develop a model that balances basin-averaged 40Ar-39Ar ages (detrital mixtures) of the contributing fluvial basins and predicts the bulk sediment value at the core site. We find that the Upper Klamath Basin (which contained pluvial Lake Modoc during Marine Isotope Stage 2) is the most influential source area that can contribute to younger bulk sediment 40Ar-39Ar ages at the core site, relative to present day values. The Eel River is also shown to have a considerable influence on changes in margin sedimentation. Combinations of increases in the sediment fluxes out of these two basins can describe the 40Ar-39Ar provenance evolution observed at the core site over the 22-14 ka time period. Overall, this new 40Ar-39Ar isotopic technique, together with the Nd isotopic system and the use of detrital mixture modeling show tremendous promise as a multi-faceted strategy to assess erosion and provenance change through the continuous history preserved in fine-grained marine sedimentary records. Close

• 91. [Article] Igneous petrology, structural geology, and mineralization of the central part of the Bayhorse Mining District, Custer County, Idaho

  The central part of the Bayhorse Mining District is located in the Salmon River Mountains in north-central Idaho between the towns of Challis and Clayton. The area is underlain by metasedimentary rocks ...

  Citation × Citation Citation Abstract Copy Title: Igneous petrology, structural geology, and mineralization of the central part of the Bayhorse Mining District, Custer County, Idaho Author: Hodges, Wade Allan The central part of the Bayhorse Mining District is located in the Salmon River Mountains in north-central Idaho between the towns of Challis and Clayton. The area is underlain by metasedimentary rocks of Early to Middle Paleozoic age that were profoundly affected by the emplacement of a plutonic complex in Middle Cretaceous time, both of which were later intruded and covered by volcanic rocks of Early Tertiary age. Both intrusive events were accompanied by significant mineralization. These basement rocks and the associated mineral deposits have been partly exposed by post-Miocene uplift and subsequent glacial and deep stream erosion. The stratigraphic succession within the Bayhorse area consists of a series of alternating pelitic, carbonate and quartzite units that range from Latest Cambrian to Middle Ordovician in age. Five sedimentary rock units have been described within the area of study and consist, from oldest to youngest, of the Garden Creek Phyllite, Bayhorse Dolomite, Ramshorn Slate, mixed lithology sequence and Clayton Mine Quartzite. The lithologic and textural varieties of the Lower Paleozoic rocks, combined with regional considerations, collectively indicate that the Bayhorse area was transitional between marine shelf areas to the west, north and east and deeper miogeosynclinal areas to the south for most of Paleozoic time. Central Idaho was affected by magmatic activity continually from Late Jurassic to Middle Cretaceous time. Synchronous with the onset of batholithic scale magmatism was folding and thrust faulting of the Paleozoic sedimentary rocks. The magmatic activity culminated in the formation of the Idaho Batholith and related outlying plutons, one of which is locally represented by the Juliette Creek intrusive complex. Geologic evidence indicates that the Juliette Creek intrusive complex represents the upper parts of a much larger and somewhat deeper plutonic mass that was forcefully emplaced into the surrounding sedimentary rocks at depths ranging from 4 to 5 miles along anticlinal axes that paralleled the north-south structural grain of the region. In approximate order of emplacement the exposed part of the intrusive complex consists of quartz diorite, granodiorite grading to granite, and quartz-feldspar porphyry. The effects of thermal metamorphism were variably imposed upon the adjacent sedimentary rocks and the resulting changes in the lithologic characteristics of the country rocks aided in the modification of the pre-existing local structure by the forceful emplacement of the intrusive complex. Hydrothermal alteration and sulfide metallization are predominantly structurally controlled and spatially, temporally and probably genetically related to the Juliette Creek intrusive complex. Fluorite mineralization is related to the later igneous activity of Early Tertiary age. The emplacement of the intrusive complex was of major importance in preparing the ground for the two later episodes of mineralization by significantly altering the pre-existing local structure and lithologic characteristics of the sedimentary rocks The predominant structural feature of the district consists of two parallel elongate folds that formed in the Paleozoic sedimentary rocks by eastwardly directed compressional movement. Subsequent ethplacement of the Juliette Creek intrusive complex has locally modified the pre-existing structure and caused the sedimentary rocks to break along predictable zones of weakness. The sulfide metallization is related to the upper parts of a large hydrothermal system that may be associated with stock-work molybdenum or porphyry-copper type mineralization at depth. After this major period of magmatic, tectonic and hydrothermal activity the rocks of the district were again affected by a later, but similar sequence of events that culminated in the eruption of the rhyodacitic, andesitic and basaltic flows and pyroclastic deposits of the Challis Volcanics and the deposition of significant fluorspar in Early Tertiary time. Title: Igneous petrology, structural geology, and mineralization of the central part of the Bayhorse Mining District, Custer County, Idaho Author: Hodges, Wade Allan The central part of the Bayhorse Mining District is located in the Salmon River Mountains in north-central Idaho between the towns of Challis and Clayton. The area is underlain by metasedimentary rocks of Early to Middle Paleozoic age that were profoundly affected by the emplacement of a plutonic complex in Middle Cretaceous time, both of which were later intruded and covered by volcanic rocks of Early Tertiary age. Both intrusive events were accompanied by significant mineralization. These basement rocks and the associated mineral deposits have been partly exposed by post-Miocene uplift and subsequent glacial and deep stream erosion. The stratigraphic succession within the Bayhorse area consists of a series of alternating pelitic, carbonate and quartzite units that range from Latest Cambrian to Middle Ordovician in age. Five sedimentary rock units have been described within the area of study and consist, from oldest to youngest, of the Garden Creek Phyllite, Bayhorse Dolomite, Ramshorn Slate, mixed lithology sequence and Clayton Mine Quartzite. The lithologic and textural varieties of the Lower Paleozoic rocks, combined with regional considerations, collectively indicate that the Bayhorse area was transitional between marine shelf areas to the west, north and east and deeper miogeosynclinal areas to the south for most of Paleozoic time. Central Idaho was affected by magmatic activity continually from Late Jurassic to Middle Cretaceous time. Synchronous with the onset of batholithic scale magmatism was folding and thrust faulting of the Paleozoic sedimentary rocks. The magmatic activity culminated in the formation of the Idaho Batholith and related outlying plutons, one of which is locally represented by the Juliette Creek intrusive complex. Geologic evidence indicates that the Juliette Creek intrusive complex represents the upper parts of a much larger and somewhat deeper plutonic mass that was forcefully emplaced into the surrounding sedimentary rocks at depths ranging from 4 to 5 miles along anticlinal axes that paralleled the north-south structural grain of the region. In approximate order of emplacement the exposed part of the intrusive complex consists of quartz diorite, granodiorite grading to granite, and quartz-feldspar porphyry. The effects of thermal metamorphism were variably imposed upon the adjacent sedimentary rocks and the resulting changes in the lithologic characteristics of the country rocks aided in the modification of the pre-existing local structure by the forceful emplacement of the intrusive complex. Hydrothermal alteration and sulfide metallization are predominantly structurally controlled and spatially, temporally and probably genetically related to the Juliette Creek intrusive complex. Fluorite mineralization is related to the later igneous activity of Early Tertiary age. The emplacement of the intrusive complex was of major importance in preparing the ground for the two later episodes of mineralization by significantly altering the pre-existing local structure and lithologic characteristics of the sedimentary rocks The predominant structural feature of the district consists of two parallel elongate folds that formed in the Paleozoic sedimentary rocks by eastwardly directed compressional movement. Subsequent ethplacement of the Juliette Creek intrusive complex has locally modified the pre-existing structure and caused the sedimentary rocks to break along predictable zones of weakness. The sulfide metallization is related to the upper parts of a large hydrothermal system that may be associated with stock-work molybdenum or porphyry-copper type mineralization at depth. After this major period of magmatic, tectonic and hydrothermal activity the rocks of the district were again affected by a later, but similar sequence of events that culminated in the eruption of the rhyodacitic, andesitic and basaltic flows and pyroclastic deposits of the Challis Volcanics and the deposition of significant fluorspar in Early Tertiary time. Close

• 92. [Article] The Deschutes Formation-- High Cascade transition in the Whitewater River area, Jefferson County, Oregon

  The Whitewater River area is located directly east of Mt. Jefferson in the Cascades of central Oregon. Approximately 90 mi2 (230 km2) were mapped (scale 1/24,000) and four new K-Ar ages and 151 major element ...

  Citation × Citation Citation Abstract Copy Title: The Deschutes Formation-- High Cascade transition in the Whitewater River area, Jefferson County, Oregon Author: Yogodzinski, Gene M. The Whitewater River area is located directly east of Mt. Jefferson in the Cascades of central Oregon. Approximately 90 mi2 (230 km2) were mapped (scale 1/24,000) and four new K-Ar ages and 151 major element analyses were obtained in a study of the stratigraphic and magmatic transition from the Miocene - Pliocene Deschutes Formation on the east to the Pliocene - Pleistocene High Cascades on the west. Deschutes strata in the Whitewater River area overlie late Miocene (8-11+ m.y.) andesites, dacites, and rhyodacites along an erosional unconformity. The oldest Deschutes rocks exposed in the Whitewater River area are approximately 6 m.y. old, and the youngest are probably between 4.5 and 5 m.y. old. The oldest High Cascade rocks exposed in the Whitewater River area are approximately 4.3 m.y. old. There is no evidence for a hiatus in volcanic activity between Deschutes and High Cascade time in the Whitewater River area. Late Pleistocene explosive volcanism, probably free Mt. Jefferson, is evidenced in a hornblende rhyodacite pyroclastic-flow deposit which occurs within the glacial stratigraphy and is tentatively thought to be between approximately 60,000 and 20,000 years old. Deschutes strata are dominated by pyroclastic lithologies (mostly ash-flow tuffs) with some lava flows and minor epiclastic sediment. Compositions range mostly between basaltic andesite and dacite. Many Deschutes-age rocks are aphyric, high in Fed, TiO2, and alkalies, and low in MgO, CaO, and A12O3. They define a tholeiitic trend extending at least from basaltic andesite to dacite that can largely be derived through fractional crystallization of plagioclase, olivine, magnetite, and clinopyroxene from a parent magma, probably of basaltic composition. These rocks are compositionally similar to "tholeiitic anorogenic andesites" that are most commonly associated with areas of crustal extension. Rocks of High Cascade age in the Whitewater River area are mostly lava flaws that range in composition from basalt (high-alumina, olivine tholeiite) to rhyodacite. The High Cascade suite forms a calc-alkalic association that is typical of subduction-related magmatic arcs. Fractional crystallization of the basalts leads to iron-enrichment. Fractional crystallization of the basaltic andesites might lead to calc-alkalic compositions, but the mineral phases necessary to deplete the magmas in FeO, TiO2, and CaO (magnetite and clinopyroxene) are not common phenocryst phases in the basaltic andesites or andesites. Two northwest-trending, down-to-the-west normal faults with sane possible strike-slip motion have been mapped in the upper Whitewater River area, directly west of Lion's Head. Motion on these faults occurred after approximately 4 m.y. ago, but probably began prior to that time. There is between 200 and 400 ft (60-120 m) of apparent vertical separation on the western side of these faults. There may be a large, northwest-trending fault running from the south end of Green Ridge, through Bald Peter and the Whitewater River area, but this structure is largely buried by younger volcanic rocks. There is no evidence for a northern extension of the north-trending Green Ridge faults, and there is no evidence for large structural displacement in the lower Whitewater River along north- or northwest-trending structures. The Deschutes Formation - High Cascade transition in the Whitewater River area is marked by a switch in the eruptive style and in the dominant magmatic compositions during Deschutes and High Cascade times. Volcanism in the Whitewater River area does not appear to have been episodic with respect to volume and/or intensity; rather, the character of magmatism has varied with time and with the tectonic style through the period immediately prior to and following the formation of the High cascade graben. Title: The Deschutes Formation-- High Cascade transition in the Whitewater River area, Jefferson County, Oregon Author: Yogodzinski, Gene M. The Whitewater River area is located directly east of Mt. Jefferson in the Cascades of central Oregon. Approximately 90 mi2 (230 km2) were mapped (scale 1/24,000) and four new K-Ar ages and 151 major element analyses were obtained in a study of the stratigraphic and magmatic transition from the Miocene - Pliocene Deschutes Formation on the east to the Pliocene - Pleistocene High Cascades on the west. Deschutes strata in the Whitewater River area overlie late Miocene (8-11+ m.y.) andesites, dacites, and rhyodacites along an erosional unconformity. The oldest Deschutes rocks exposed in the Whitewater River area are approximately 6 m.y. old, and the youngest are probably between 4.5 and 5 m.y. old. The oldest High Cascade rocks exposed in the Whitewater River area are approximately 4.3 m.y. old. There is no evidence for a hiatus in volcanic activity between Deschutes and High Cascade time in the Whitewater River area. Late Pleistocene explosive volcanism, probably free Mt. Jefferson, is evidenced in a hornblende rhyodacite pyroclastic-flow deposit which occurs within the glacial stratigraphy and is tentatively thought to be between approximately 60,000 and 20,000 years old. Deschutes strata are dominated by pyroclastic lithologies (mostly ash-flow tuffs) with some lava flows and minor epiclastic sediment. Compositions range mostly between basaltic andesite and dacite. Many Deschutes-age rocks are aphyric, high in Fed, TiO2, and alkalies, and low in MgO, CaO, and A12O3. They define a tholeiitic trend extending at least from basaltic andesite to dacite that can largely be derived through fractional crystallization of plagioclase, olivine, magnetite, and clinopyroxene from a parent magma, probably of basaltic composition. These rocks are compositionally similar to "tholeiitic anorogenic andesites" that are most commonly associated with areas of crustal extension. Rocks of High Cascade age in the Whitewater River area are mostly lava flaws that range in composition from basalt (high-alumina, olivine tholeiite) to rhyodacite. The High Cascade suite forms a calc-alkalic association that is typical of subduction-related magmatic arcs. Fractional crystallization of the basalts leads to iron-enrichment. Fractional crystallization of the basaltic andesites might lead to calc-alkalic compositions, but the mineral phases necessary to deplete the magmas in FeO, TiO2, and CaO (magnetite and clinopyroxene) are not common phenocryst phases in the basaltic andesites or andesites. Two northwest-trending, down-to-the-west normal faults with sane possible strike-slip motion have been mapped in the upper Whitewater River area, directly west of Lion's Head. Motion on these faults occurred after approximately 4 m.y. ago, but probably began prior to that time. There is between 200 and 400 ft (60-120 m) of apparent vertical separation on the western side of these faults. There may be a large, northwest-trending fault running from the south end of Green Ridge, through Bald Peter and the Whitewater River area, but this structure is largely buried by younger volcanic rocks. There is no evidence for a northern extension of the north-trending Green Ridge faults, and there is no evidence for large structural displacement in the lower Whitewater River along north- or northwest-trending structures. The Deschutes Formation - High Cascade transition in the Whitewater River area is marked by a switch in the eruptive style and in the dominant magmatic compositions during Deschutes and High Cascade times. Volcanism in the Whitewater River area does not appear to have been episodic with respect to volume and/or intensity; rather, the character of magmatism has varied with time and with the tectonic style through the period immediately prior to and following the formation of the High cascade graben. Close

• 93. [Image] The geology and petrography of Crater lake national park

  	167, iii p.; xix pl. (incl. 2 maps); Geology by J.S. Diller; Petrography by H.B. Patton; 35.00S
  	Citation × Citation Citation Abstract Copy Title: The geology and petrography of Crater lake national park Author: Diller, Joseph Silas; Patton, Horace Bushnell Year: 1902, 2006 167, iii p.; xix pl. (incl. 2 maps); Geology by J.S. Diller; Petrography by H.B. Patton; 35.00S Title: The geology and petrography of Crater lake national park Author: Diller, Joseph Silas; Patton, Horace Bushnell Year: 1902, 2006 167, iii p.; xix pl. (incl. 2 maps); Geology by J.S. Diller; Petrography by H.B. Patton; 35.00S Close

• 94. [Article] Deep-sea sediment paleomagnetism : a case study from the North Atlantic

  Sedimentary records from the North Atlantic, instrumental in the development of modern paleo-geomagnetic concepts, show a highly variable field even during times of constant polarity. Yet, our understanding ...

  Citation × Citation Citation Abstract Copy Title: Deep-sea sediment paleomagnetism : a case study from the North Atlantic Author: Strano, Sarah Elianna Sedimentary records from the North Atlantic, instrumental in the development of modern paleo-geomagnetic concepts, show a highly variable field even during times of constant polarity. Yet, our understanding of how the magnetization is acquired in the sediments is poorly understood. Primary magnetizations preserved in deep-sea sediments are known to be acquired through a depositional or possibly, a post-depositional remanent magnetization (DRM or pDRM). A pDRM process implies that the magnetization is locked-in at depth creating an offset between the age of the magnetization and the age of sediment. The process is not currently accounted for in paleomagnetic records despite the wide use of magnetic records to elucidate the timing and rate of change of many paleomagnetic and environmental processes. This dissertation uses seven Northern North Atlantic (NNA) deep-sea sediment cores that were studied by alternating field demagnetization of natural and laboratory imposed remanence on uchannel samples, providing for detailed paleomagnetic and environmental magnetic records. These high-quality Holocene and deglacial magnetic data are combined with independent radiocarbon chronologies to better understand the: (1) magnetic acquisition process, (2) the NNA paleo-geomagnetic signal and (3) the influence of rock magnetic parameters on the sedimentary paleomagnetic record. Under the traditional paradigm of magnetostratigraphy, sediment deposition and magnetization are assumed to occur synchronously and with little to no signal attenuation. In Chapter 2, we compare independently dated Holocene paleomagnetic records from the seven deep-sea sediments cores across the North Atlantic with regional paleo-geomagnetic reconstructions derived from ultra-high resolution sediment records. We find variable delays between the timing of these records, consistent with a magnetization “locked-in” at depth and over an interval that results in smoothing of the geomagnetic signal. Optimization modeling of the post-depositional remanent magnetization (pDRM) accounts for both offset and some of this smoothing. It also demonstrates that the preserved magnetization is acquired ~20 cm below the sediment-water interface. Consistent with previous observations, this potentially ubiquitous process results in age offsets of 350-2000 years even in deep-sea sediment accumulation rates in excess of 10 cm/kyr that is rarely if ever accounted for in magnetostratigraphy or paleomagnetic records. In Chapter 3, we assume that the new pDRM-corrected chronologies developed for Chapter 2 more accurately represent each paleomagnetic record and create a NNA stack of both direction and intensity from ~15,000 years ago to present (NAPstack15). Uncertainty analyses and comparison to data derived from global field models at the same locations suggest that both, our directional and intensity stacks robustly capture the evolution of the mean geomagnetic field variations of the NNA. Broader regional comparisons with data from North America and Europe begin to define the evolution of the geomagnetic field during this time interval. Geomagnetic morphology and spatial/temporal variability can be roughly broken into three time intervals consistent with the evolution of global intensity and implicate the dynamics of the high-latitude Holocene flux patches as a source of this variability. We evaluate the effect of rock magnetic properties on the fidelity of the NNA paleomagnetic record from the Holocene through the last deglaciation. NNA records have been argued to consistently record high-quality paleomagnetic records over millennial to orbital time scales with little concern for lithologic variability resulting from glacial-interglacial environmental changes. We find that rock magnetic variability has little effect on the fidelity of the NNA's directional record, but has a variable and sometimes large influence on normalized remanence records, which are commonly used as a relative paleomagnetic intensity proxy. We find that the eastern NNA records are most affected by the use of different normalizers during the Holocene. The western NNA cores are more affected by the use of different normalizers during the deglacial period but to a lesser extent. The Iceland Basin cores are an exception, providing consistent normalized remanence records regardless of the normalizer during both the Holocene and deglacial interval. This likely reflects their proximity to Icelandic basaltic sources and the consistent magnetite grain-size regardless of physical grain-size that these sources provide. Title: Deep-sea sediment paleomagnetism : a case study from the North Atlantic Author: Strano, Sarah Elianna Sedimentary records from the North Atlantic, instrumental in the development of modern paleo-geomagnetic concepts, show a highly variable field even during times of constant polarity. Yet, our understanding of how the magnetization is acquired in the sediments is poorly understood. Primary magnetizations preserved in deep-sea sediments are known to be acquired through a depositional or possibly, a post-depositional remanent magnetization (DRM or pDRM). A pDRM process implies that the magnetization is locked-in at depth creating an offset between the age of the magnetization and the age of sediment. The process is not currently accounted for in paleomagnetic records despite the wide use of magnetic records to elucidate the timing and rate of change of many paleomagnetic and environmental processes. This dissertation uses seven Northern North Atlantic (NNA) deep-sea sediment cores that were studied by alternating field demagnetization of natural and laboratory imposed remanence on uchannel samples, providing for detailed paleomagnetic and environmental magnetic records. These high-quality Holocene and deglacial magnetic data are combined with independent radiocarbon chronologies to better understand the: (1) magnetic acquisition process, (2) the NNA paleo-geomagnetic signal and (3) the influence of rock magnetic parameters on the sedimentary paleomagnetic record. Under the traditional paradigm of magnetostratigraphy, sediment deposition and magnetization are assumed to occur synchronously and with little to no signal attenuation. In Chapter 2, we compare independently dated Holocene paleomagnetic records from the seven deep-sea sediments cores across the North Atlantic with regional paleo-geomagnetic reconstructions derived from ultra-high resolution sediment records. We find variable delays between the timing of these records, consistent with a magnetization “locked-in” at depth and over an interval that results in smoothing of the geomagnetic signal. Optimization modeling of the post-depositional remanent magnetization (pDRM) accounts for both offset and some of this smoothing. It also demonstrates that the preserved magnetization is acquired ~20 cm below the sediment-water interface. Consistent with previous observations, this potentially ubiquitous process results in age offsets of 350-2000 years even in deep-sea sediment accumulation rates in excess of 10 cm/kyr that is rarely if ever accounted for in magnetostratigraphy or paleomagnetic records. In Chapter 3, we assume that the new pDRM-corrected chronologies developed for Chapter 2 more accurately represent each paleomagnetic record and create a NNA stack of both direction and intensity from ~15,000 years ago to present (NAPstack15). Uncertainty analyses and comparison to data derived from global field models at the same locations suggest that both, our directional and intensity stacks robustly capture the evolution of the mean geomagnetic field variations of the NNA. Broader regional comparisons with data from North America and Europe begin to define the evolution of the geomagnetic field during this time interval. Geomagnetic morphology and spatial/temporal variability can be roughly broken into three time intervals consistent with the evolution of global intensity and implicate the dynamics of the high-latitude Holocene flux patches as a source of this variability. We evaluate the effect of rock magnetic properties on the fidelity of the NNA paleomagnetic record from the Holocene through the last deglaciation. NNA records have been argued to consistently record high-quality paleomagnetic records over millennial to orbital time scales with little concern for lithologic variability resulting from glacial-interglacial environmental changes. We find that rock magnetic variability has little effect on the fidelity of the NNA's directional record, but has a variable and sometimes large influence on normalized remanence records, which are commonly used as a relative paleomagnetic intensity proxy. We find that the eastern NNA records are most affected by the use of different normalizers during the Holocene. The western NNA cores are more affected by the use of different normalizers during the deglacial period but to a lesser extent. The Iceland Basin cores are an exception, providing consistent normalized remanence records regardless of the normalizer during both the Holocene and deglacial interval. This likely reflects their proximity to Icelandic basaltic sources and the consistent magnetite grain-size regardless of physical grain-size that these sources provide. Close

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

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

• 96. [Image] The trout and salmon of the Pacific coast

  	This article is an overview of the variety of trout and salmon that are found in Oregon and Washington states.
  	Citation × Citation Citation Abstract Copy Title: The trout and salmon of the Pacific coast Author: Jordan, David Starr Year: 1906, 2005, 2004 This article is an overview of the variety of trout and salmon that are found in Oregon and Washington states. Title: The trout and salmon of the Pacific coast Author: Jordan, David Starr Year: 1906, 2005, 2004 This article is an overview of the variety of trout and salmon that are found in Oregon and Washington states. Close

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

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

• 98. [Image] Defining and evaluating recovery of OCN coho salmon stocks : implications for rebuilding stocks under the Oregon Plan : summary of a workshop organized by the Independent Multidisciplinary Science Team, August 4-5, 1999

  	"December 10, 1999."
  	Citation × Citation Citation Abstract Copy Title: Defining and evaluating recovery of OCN coho salmon stocks : implications for rebuilding stocks under the Oregon Plan : summary of a workshop organized by the Independent Multidisciplinary Science Team, August 4-5, 1999 Author: Independent Multidisciplinary Science Team (Or.) Year: 1999, 2005 "December 10, 1999." Title: Defining and evaluating recovery of OCN coho salmon stocks : implications for rebuilding stocks under the Oregon Plan : summary of a workshop organized by the Independent Multidisciplinary Science Team, August 4-5, 1999 Author: Independent Multidisciplinary Science Team (Or.) Year: 1999, 2005 "December 10, 1999." Close

• 99. [Image] The Water Report - The role of science in the ESA

  	Only portions of issues of The Water Report are available in the Klamath Waters Digital Library. See the full report at http://www.thewaterreport.com/
  	Citation × Citation Citation Abstract Copy Title: The Water Report - The role of science in the ESA Author: Envirotech Publications Year: 2004, 2008, 2006 Only portions of issues of The Water Report are available in the Klamath Waters Digital Library. See the full report at http://www.thewaterreport.com/ Title: The Water Report - The role of science in the ESA Author: Envirotech Publications Year: 2004, 2008, 2006 Only portions of issues of The Water Report are available in the Klamath Waters Digital Library. See the full report at http://www.thewaterreport.com/ Close

• 100. [Image] EPA 314 clean lakes program: phase I diagnostic/feasibility project: Upper Klamath Lake, Oregon

  	SUMMARY PROBLEM DEFINITION Upper Klamath Lake, a 90,000 acre body of water located in south-central Oregon, is eutrophic and has reached a stage where summer algal and macrophyte productivity causes ...
  	Citation × Citation Citation Abstract Copy Title: EPA 314 clean lakes program: phase I diagnostic/feasibility project: Upper Klamath Lake, Oregon Author: Klamath Consulting Service, Inc Year: 1983, 2006, 2005 SUMMARY PROBLEM DEFINITION Upper Klamath Lake, a 90,000 acre body of water located in south-central Oregon, is eutrophic and has reached a stage where summer algal and macrophyte productivity causes severe aesthetic problems and often renders the lake unusable as a recreational site. The problem is a natural one; it has not been caused by man's carelessness and cannot be turned around by regulation. Upper Klamath Lake is quite shallow, warming rapidly in the summer, and the waters carry a naturally occurring high nutrient load. Algal growth is extensive, predominently APHANEZOMENON FLOS-AQUAE, a blue-green algae prevalent in eutrophic waters. These organisms form dense mats that become very odorous as they decay. Numerous macrophytes (aquatic weeds) are indigenous to the lake, but the major problem is with P0TAM06ET0N CRISPUS, which forms long floating fonds that tangle boat motors and prevent passage. The Pelican Bay channel has an extensive growth of this weed. Title: EPA 314 clean lakes program: phase I diagnostic/feasibility project: Upper Klamath Lake, Oregon Author: Klamath Consulting Service, Inc Year: 1983, 2006, 2005 SUMMARY PROBLEM DEFINITION Upper Klamath Lake, a 90,000 acre body of water located in south-central Oregon, is eutrophic and has reached a stage where summer algal and macrophyte productivity causes severe aesthetic problems and often renders the lake unusable as a recreational site. The problem is a natural one; it has not been caused by man's carelessness and cannot be turned around by regulation. Upper Klamath Lake is quite shallow, warming rapidly in the summer, and the waters carry a naturally occurring high nutrient load. Algal growth is extensive, predominently APHANEZOMENON FLOS-AQUAE, a blue-green algae prevalent in eutrophic waters. These organisms form dense mats that become very odorous as they decay. Numerous macrophytes (aquatic weeds) are indigenous to the lake, but the major problem is with P0TAM06ET0N CRISPUS, which forms long floating fonds that tangle boat motors and prevent passage. The Pelican Bay channel has an extensive growth of this weed. Close