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At least 1,099 records · Page 61Linked to original sources
USGS1970

A re-evaluation of basalt-obsidian relations at East Lake Fissure, Newberry Caldera, Oregon

Andesite scoria, agglutinate, and small flows formed by thin lava gushes that erupted from East Lake Fissure on the north wall of Newberry Caldera carry numerous inclusions of platy rhyolite, partly melted platy rhyolite, and frothy obsidian. This association of obsidian and “basalt” has been interpreted as the result of intermingling of mafic and siliceous magmas. The locality has been repeatedly cited as an example of a mixed intrusion of the “basalt-rhyolite association.” Field, petrographic, chemical, and experimental evidence suggest, however, that the inclusions of frothy and massive obsidian are melted fragments of platy rhyolite which were ripped from a rhyolite unit forming part of the caldera wall by uncontaminated andesite magma which rose and fountained from the fissure.

Oregon↗
USGS2014

Gravity, magnetic, and radiometric data for Newberry Volcano, Oregon, and vicinity

Newberry Volcano in central Oregon is a 3,100-square-kilometer (1,200-square-mile) shield-shaped composite volcano, occupying a location east of the main north-south trend of the High Cascades volcanoes and forming a transition between the High Lava Plains subprovince of the Basin and Range Province to the east and the Cascade Range to the west. Magnetic, gravity, and radiometric data have been gathered and assessed for the region around the volcano. These data have widely varying quality and resolution, even within a given dataset, and these limitations are evaluated and described in this release. Publicly available gravity data in general are too sparse to permit detailed modeling except along a few roads with high-density coverage. Likewise, magnetic data are also unsuitable for all but very local modeling, primarily because available data consist of a patchwork of datasets with widely varying line-spacing. Gravity data show only the broadest correlation with mapped geology, whereas magnetic data show moderate correlation with features only in the vicinity of Newberry Caldera. At large scales, magnetic data correlate poorly with both geologic mapping and gravity data. These poor correlations are largely due to the different sensing depths of the two potential fields methods, which respond to physical properties deeper than the surficial geology. Magnetic data derive from rocks no deeper than the Curie-point isotherm depth (10 to 15 kilometers, km, maximum), whereas gravity data reflect density-contrasts to 100 to 150 km depths. Radiometric data from the National Uranium Resource Evaluation (NURE) surveys of the 1980s have perhaps the coarsest line-spacing of all (as much as 10 km between lines) and are extremely “noisy” for several reasons inherent to this kind of data. Despite its shallow-sensing character, only a few larger anomalies in the NURE data correlate well with geologic mapping. The purpose of this data series release is to collect and place the available geophysical data in the hands of other investigators in a readily comprehensible form. All data-compilation, splicing, filtering, and overlay-map displays were accomplished with the commercial Geosoft™ system, Advanced Option. Images are provided in both JPG and PDF formats.

Oregon↗
USGS1980

Depositional environments of some Pleistocene coastal terrace deposits, southwestern Oregon - case history of progradational beach and dune sequence.

These deposits comprise a basal gravelly unit and 3 overlying sandy units, each with mud beds, a paleosol, or the modern soil in its uppermost part. The gravelly unit is interpreted as a progradational deposit. The main parts of the sandy units are made up of 1) a crossbedded sand facies, the dominant structure in which is medium-scale crossbedding (interpreted as the product of small eolian dunes), and 2) an irregularly bedded sand facies, which is locally pebbly and is dominated by scour-and-fill structures, interpreted as deposits of interdune ephemeral streams, ephemeral ponds, and wet to dry subaerial flats. The mud beds and paleosols represent times of temporary stabilization of the dune field.- from Author

Sedimentary Geology↗
USGS2020

Juvenile Lost River and shortnose sucker year-class formation, survival, and growth in Upper Klamath Lake, Oregon and Clear Lake Reservoir, California—2017 Monitoring Report

Executive Summary Populations of federally endangered Lost River ( Deltistes luxatus ) and shortnose suckers ( Chasmistes brevirostris ) in Upper Klamath Lake, Oregon, and Clear Lake Reservoir (hereinafter referred to as Clear Lake; fig. 1), California, are experiencing long-term declines in abundance. Upper Klamath Lake populations are decreasing because juvenile suckers are not surviving and recruiting into the adult population. Most juvenile sucker mortality occurs within the first year of life in Upper Klamath Lake. Annual production of juvenile suckers in Clear Lake appear to be highly variable and may not occur at all in very dry years. However, juvenile sucker survival is much higher in Clear Lake, with some suckers surviving to join spawning aggregations. Long-term monitoring of juvenile sucker populations is needed to 1) determine if there are annual and species-specific differences in production, survival, and growth; 2) better understand when juvenile sucker mortality is greatest; 3) help identify potential causes of high juvenile sucker mortality particularly in Upper Klamath Lake; and 4) monitor for successful juvenile survival in Upper Klamath Lake. The U.S. Geological Survey (USGS) began a summer juvenile sucker monitoring program in 2015 to track cohorts over time in Upper Klamath and Clear Lakes. The juvenile sucker monitoring program involved using trap net data at fixed sites to determine the status of juvenile suckers. Annual variability in apparent age-0 sucker production, juvenile sucker survival, and growth were tracked. Using genetic markers, suckers were classified as one of three taxa; shortnose (combinations of shortnose and Klamath largescale suckers), Lost River, or suckers with genetic markers of both species (Intermediate [Prob]). By using catch data, we generated taxa-specific indices of year-class strength, August–September apparent survival, and overwinter apparent survival. We also examined the prevalence and severity of afflictions such as parasites, wounds, and deformities. The Upper Klamath Lake year-class strength indices for both Lost River and shortnose suckers were slightly lower in 2015 and 2017 than in 2016. The ratios of age-0 Lost River suckers to age-0 shortnose suckers captured in August in Upper Klamath Lake were low in 2015 and 2017, given that adult Lost River suckers are more abundant and more fecund than adult shortnose suckers. This may indicate lower egg, larval, or juvenile survival or poorer spawning success for Lost River suckers than shortnose suckers in these two years. Apparent relative age-0 survival indices for Lost River suckers from August to September in Upper Klamath Lake were greater in 2015 (0.29) than in 2016 (0.16) or 2017 (0.14). Age-0 shortnose sucker catch rates increased between August and September in 2015, possibly indicating new individuals of this species were still recruiting to the lake between the two sampling periods. August to September relative survival indices for Upper Klamath Lake shortnose suckers were 0.35 in 2016 and 0.00 in 2017. We predicted year-class strength would be greater in Clear Lake in years when high spring-time lake elevations and instream flow allowed adult suckers access to spawning habitat in the Willow Creek drainage. Instream flows and lake elevations were sufficient to allow adult suckers to access Willow Creek during the 2016 and 2017 spawning seasons, and age-0 suckers were detected in Clear Lake both years. Higher lake surface elevations and instream flows in 2017 than in 2016 were not associated with higher year-class strength indices in 2017 than in 2016. Low lake surface elevations appeared to limit access by adults to Willow Creek during the 2014 and 2015 spawning seasons and age-0 suckers were not detected in Clear Lake during these years. Nineteen shortnose suckers from the 2014 cohort were captured in Clear Lake in 2017. A 2015 cohort of shortnose suckers was captured as age-1 in 2016 and as age-2 in 2017. The most likely explanation for increasing catch rates of the 2015 cohort is that the higher Willow Creek flows in 2016 and 2017 facilitated the movement of stream-resident suckers, spawned in 2014 and 2015 downstream into Clear Lake. Due to uncertainty in the genetic identification of non-Lost River suckers, these fish are equally likely to be Klamath largescale or shortnose suckers (Hoy and Ostberg, 2015).

California, Oregon↗
USGS1994

The northern Nevada rift: Regional tectono-magmatic relations and Middle Miocene stress direction

As defined by the most recent aeromagnetic surveys, the north-northwest-trending northern Nevada rift zone extends for at least 500 km from southern Nevada to the Oregon Nevada border. At several places along the rift, the magnetic anomaly is clearly related to north-northwest-trending dikes and flows that, based on new radiometric dating, erupted between 17 and 14 Ma and probably during an even shorter time interval. The tectonic significance of the rift is dramatized by its length, its coincidence in time and space (at its northern terminus) with the oldest silicic caldera complex along the Yellowstone hot-spot trend, and its parallelism with the subduction zone along the North American coast prior to the establishment of the San Andreas fault.

Geological Society of America Bulletin↗
USGS1998

Fore-arc migration in Cascadia and its neotectonic significance

Neogene deformation, paleomagnetic rotations, and sparse geodetic data suggest the Cascadia fore arc is migrating northward along the coast and breaking up into large rotating blocks. Deformation occurs mostly around the margins of a large, relatively aseismic Oregon coastal block composed of thick, accreted seamount crust. This 400-km-long block is moving slowly clockwise with respect to North America about a Euler pole in eastern Washington, thus increasing convergence rates along its leading edge near Cape Blanco, and creating an extensional volcanic arc on its trailing edge. Northward movement of the block breaks western Washington into smaller, seismically active blocks and compresses them against the Canadian Coast Mountains restraining bend. Arc-parallel transport of fore-arc blocks is calculated to be up to 9 mm/yr, sufficient to produce damaging earthquakes in a broad deformation zone along block margins.

Geology↗
USGS2008

Digital data for volcano hazards at Newberry Volcano, Oregon

Newberry volcano is a broad shield volcano located in central Oregon, the product of thousands of eruptions, beginning about 600,000 years ago. At least 25 vents on the flanks and summit have been active during the past 10,000 years. The most recent eruption 1,300 years ago produced the Big Obsidian Flow. Thus, the volcano's long history and recent activity indicate that Newberry will erupt in the future. Newberry Crater, a volcanic depression or caldera has been the focus of Newberry's volcanic activity for at least the past 10,000 years. Newberry National Volcanic Monument, which is managed by the U.S. Forest Service, includes the caldera and extends to the Deschutes River. Newberry volcano is quiet. Local earthquake activity (seismicity) has been trifling throughout historic time. Subterranean heat is still present, as indicated by hot springs in the caldera and high temperatures encountered during exploratory drilling for geothermal energy. The report USGS Open-File Report 97-513 (Sherrod and others, 1997) describes the kinds of hazardous geologic events that might occur in the future at Newberry volcano. A hazard-zonation map is included to show the areas that will most likely be affected by renewed eruptions. When Newberry volcano becomes restless, the eruptive scenarios described herein can inform planners, emergency response personnel, and citizens about the kinds and sizes of events to expect. The geographic information system (GIS) volcano hazard data layers used to produce the Newberry volcano hazard map in USGS Open-File Report 97-513 are included in this data set. Scientists at the USGS Cascades Volcano Observatory created a GIS data layer to depict zones subject to the effects of an explosive pyroclastic eruption (tephra fallout, pyroclastic flows, and ballistics), lava flows, volcanic gasses, and lahars/floods in Paulina Creek. A separate GIS data layer depicts drill holes on the flanks of Newberry Volcano that were used to estimate the probability of coverage by future lava flows.

Open-File Report↗
USGS1985

Gas hydrates on the northern California continental margin

The inner continental margin of northern California is underlain by a well-defined and extensive acoustic reflector that crosses other reflectors and mimics the surface of the sea floor. This bottom-simulating reflector (BSR) lies at a typical subsurface depth of about 250 m and has been mapped continuously beneath the Klamath Plateau and upper slope (water depths of 800 to 1200 m) for a distance of more than 130 km; it covers an area of at least 3000 km 2 . Limited data show that the BSR extends northward into Oregon and seaward at least to the base of the slope (3000 m). The water depths, subsurface depths, and pervasive nature of the BSR all suggest that it represents the base of a natural-gas hydrate. Using standard phase boundary diagrams for hydrate stability, we estimate the local geothermal gradient within the gas hydrate to be about 55 °C/km. This value is higher than that of most subduction margins and may be a result of the youthfulness of the subducting oceanic crust. This acoustically inferred gas hydrate is the first to be mapped on the western conterminous United States continental margin.

California↗
USGS2004

Magmatic intrusion west of Three Sisters, central Oregon, USA: The perspective from spring geochemistry

A geochemical investigation of springs near Three Sisters volcanoes was conducted in response to the detection of crustal uplift west of the peaks. Dilute, low-temperature springs near the center of uplift show 3 He/ 4 He ratios ≥7 R A ( R A is the ratio in air), and transport in total ∼16 MW of heat and ∼180 g/s of magmatic carbon (as CO 2 ). These anomalous conditions clearly reflect the influence of magma, but they seemingly predate the onset of the present uplift and derive from a previous event. Episodes of intrusion may thus be more common in this area than the age of eruptive vents would imply.

Geology↗
USGS1993

Damages from the 20 September earthquakes near Klamath Falls, Oregon

The Klamath Falls earthquakes of 8:28PM PDT (magnitude 5.9) and 10:45 PM PDT (magnitude 6.0) on September 20, 1993, were felt over an area of about 130,000 sq km in southwestern Oregon and northern California. Losses due to property damage are preliminary estimated to be about 7.5 million. A motorist died when the car he was driving was crushed by a boulder in an earthquake-induced rockfall, and an elderly woman died of a heart attack that was apparently triggered by one of the earthquakes. Most of the damage resulting from the earthquakes was reported from Klamath Falls, approximately 20 km from the source region of earthquakes. As has commonly been the case with earthquakes in other parts of the United States, the degree of damage was highly uneven in Klamath Falls. Most of the town escaped with little damage to buildings or building contents. Losses were concentrated in the downtown area, but even there most of the buildings were not damaged. The unevenness of damage in earthquakes results primarily from large differences in the seismic resistance of individual buildings and differences in the seismic response due to different soil conditions and geology beneath buildings.

Oregon↗
USGS2010

Attributes for NHDPlus Catchments (Version 1.1) for the Conterminous United States: Mean Annual R-factor, 1971-2000

This data set represents the average annual R-factor, rainfall-runoff erosivity measure, compiled for every catchment of NHDPlus for the conterminous United States. The source data are from Christopher Daly of the Spatial Climate Analysis Service, Oregon State University, and George Taylor of the Oregon Climate Service, Oregon State University (2002), who developed spatially distributed estimates of R-factor for the period 1971-2000 for the conterminous United States. The NHDPlus Version 1.1 is an integrated suite of application-ready geospatial datasets that incorporates many of the best features of the National Hydrography Dataset (NHD) and the National Elevation Dataset (NED). The NHDPlus includes a stream network (based on the 1:100,00-scale NHD), improved networking, naming, and value-added attributes (VAAs). NHDPlus also includes elevation-derived catchments (drainage areas) produced using a drainage enforcement technique first widely used in New England, and thus referred to as "the New England Method." This technique involves "burning in" the 1:100,000-scale NHD and when available building "walls" using the National Watershed Boundary Dataset (WBD). The resulting modified digital elevation model (HydroDEM) is used to produce hydrologic derivatives that agree with the NHD and WBD. Over the past two years, an interdisciplinary team from the U.S. Geological Survey (USGS), and the U.S. Environmental Protection Agency (USEPA), and contractors, found that this method produces the best quality NHD catchments using an automated process (USEPA, 2007). The NHDPlus dataset is organized by 18 Production Units that cover the conterminous United States. The NHDPlus version 1.1 data are grouped by the U.S. Geologic Survey's Major River Basins (MRBs, Crawford and others, 2006). MRB1, covering the New England and Mid-Atlantic River basins, contains NHDPlus Production Units 1 and 2. MRB2, covering the South Atlantic-Gulf and Tennessee River basins, contains NHDPlus Production Units 3 and 6. MRB3, covering the Great Lakes, Ohio, Upper Mississippi, and Souris-Red-Rainy River basins, contains NHDPlus Production Units 4, 5, 7 and 9. MRB4, covering the Missouri River basins, contains NHDPlus Production Units 10-lower and 10-upper. MRB5, covering the Lower Mississippi, Arkansas-White-Red, and Texas-Gulf River basins, contains NHDPlus Production Units 8, 11 and 12. MRB6, covering the Rio Grande, Colorado and Great Basin River basins, contains NHDPlus Production Units 13, 14, 15 and 16. MRB7, covering the Pacific Northwest River basins, contains NHDPlus Production Unit 17. MRB8, covering California River basins, contains NHDPlus Production Unit 18.

Data Series↗
USGS2020

Procedures for developing multi-period response spectra at non-conterminous United States sites

This study complements proposals to the Provisions Update Committee of the Building Seismic Safety Council that would incorporate multi-period response spectra (MPRS) in the 2020 edition of the NEHRP Recommended Seismic Provisions for New Buildings and Other Structures (2020 NEHRP Provisions) and related proposals to the ASCE 7-22 Seismic Subcommittee of the American Society of Civil Engineers for incorporation of MPRS in ASCE Standard, ASCE/SEI 7-22, Minimum Design Loads and Associated Criteria for Buildings and Other Structures (ASCE 7-22). Ultimately, the intent is that the proposed MPRS and related design requirements of ASCE 7-22 would be adopted, by reference, as part of the 2024 International Building Code. The technical basis and associated methods herein enable the U.S. Geological Survey (USGS) to develop MPRS for sites in non-conterminous U.S. regions for which seismic hazard analyses have not yet been updated by the USGS to fully define all 22 periods and eight site classes of interest in the MPRS related proposals for the 2020 NEHRP Provisions and ASCE 7-22. These regions include Alaska, Hawaii, Guam and the Northern Mariana Islands, Puerto Rico and the U.S. Virgin Islands, and American Samoa. The methods developed can be used to derive MPRS using only the three currently available ground motion parameters S S , S 1 , and T L for all nonconterminous United States regions of interest. The methods include models that characterize generic shapes of Risk-Targeted Maximum Considered Earthquake (MCE R ) ground motions as a function of these three parameters. For deriving MPRS that represent probabilistic MCE R ground motions, models are based on statistical analyses of large sample sets of probabilistic MCE R response spectra for Western United States (WUS) and Cascadia sites in California, Oregon, Washington (including Puget Sound), Idaho, and Nevada. For deriving MPRS that represent deterministic MCE R ground motions, models are based on sets of deterministic MCE R response spectra calculated using WUS shallow crustal ground motion models for earthquake magnitudes and shaking levels typical of sites governed by deterministic MCE R ground motions.

Alaska, American Samoa, Hawaii, Guam and the North↗
USGS2001

The variability of root cohesion as an influence on shallow landslide susceptibility in the Oregon Coast Range

Decades of quantitative measurement indicate that roots can mechanically reinforce shallow soils in forested landscapes. Forests, however, have variations in vegetation species and age which can dominate the local stability of landslide-initiation sites. To assess the influence of this variability on root cohesion we examined scarps of landslides triggered during large storms in February and November of 1996 in the Oregon Coast Range and hand-dug soil pits on stable ground. At 41 sites we estimated the cohesive reinforcement to soil due to roots by determining the tensile strength, species, depth, orientation, relative health, and the density of roots 1 mm in diameter within a measured soil area. We found that median lateral root cohesion ranges from 6.8–23.2 kPa in industrial forests with significant understory and deciduous vegetation to 25.6–94.3 kPa in natural forests dominated by coniferous vegetation. Lateral root cohesion in clearcuts is uniformly 10 kPa. Some 100-year-old industrial forests have species compositions, lateral root cohesion, and root diameters that more closely resemble 10-year-old clearcuts than natural forests. As such, the influence of root cohesion variability on landslide susceptibility cannot be determined solely from broad age classifications or extrapolated from the presence of one species of vegetation. Furthermore, the anthropogenic disturbance legacy modifies root cohesion for at least a century and should be considered when comparing contemporary landslide rates from industrial forests with geologic background rates.

Oregon↗
USGS1991

Neogene rotations and quasicontinuous deformation of the Pacific Northwest continental margin

Paleomagnetically determined rotations about vertical axes of 15 to 12 Ma flows of the Miocene Columbia River Basalt Group of Oregon and Washington decrease smoothly with distance from the plate margin, consistent with a simple physical model for continental deformation that assumes the lithosphere behaves as a thin layer of fluid. The average rate of northward translation of the continental margin since 15 Ma calculated from the rotations, using this model, is about 15 mm/yr, which suggests that much of the tangential motion between the Juan de Fuca and North American plates since middle Miocene time has been taken up by deformation of North America. The fluid-like character of the large-scale deformation implies that the brittle upper crust follows the motions of the deeper parts of the lithosphere.

Geology↗
USGS2010

Comparison of watershed disturbance predictive models for stream benthic macroinvertebrates for three distinct ecoregions in western US

The successful use of macroinvertebrates as indicators of stream condition in bioassessments has led to heightened interest throughout the scientific community in the prediction of stream condition. For example, predictive models are increasingly being developed that use measures of watershed disturbance, including urban and agricultural land-use, as explanatory variables to predict various metrics of biological condition such as richness, tolerance, percent predators, index of biotic integrity, functional species traits, or even ordination axes scores. Our primary intent was to determine if effective models could be developed using watershed characteristics of disturbance to predict macroinvertebrate metrics among disparate and widely separated ecoregions. We aggregated macroinvertebrate data from universities and state and federal agencies in order to assemble stream data sets of high enough density appropriate for modeling in three distinct ecoregions in Oregon and California. Extensive review and quality assurance of macroinvertebrate sampling protocols, laboratory subsample counts and taxonomic resolution was completed to assure data comparability. We used widely available digital coverages of land-use and land-cover data summarized at the watershed and riparian scale as explanatory variables to predict macroinvertebrate metrics commonly used by state resource managers to assess stream condition. The “best” multiple linear regression models from each region required only two or three explanatory variables to model macroinvertebrate metrics and explained 41–74% of the variation. In each region the best model contained some measure of urban and/or agricultural land-use, yet often the model was improved by including a natural explanatory variable such as mean annual precipitation or mean watershed slope. Two macroinvertebrate metrics were common among all three regions, the metric that summarizes the richness of tolerant macroinvertebrates (RICHTOL) and some form of EPT (Ephemeroptera, Plecoptera, and Trichoptera) richness. Best models were developed for the same two invertebrate metrics even though the geographic regions reflect distinct differences in precipitation, geology, elevation, slope, population density, and land-use. With further development, models like these can be used to elicit better causal linkages to stream biological attributes or condition and can be used by researchers or managers to predict biological indicators of stream condition at unsampled sites.

Ecological Indicators↗
USGS2012

User’s guide and metada for the PICES Nonindigenous Species Information System

Introduction Welcome to the PICES Nonindigenous Species Information System, a Microsoft Access database that displays the biogeographic distributions, invasion status, vectors, and key life history attributes of the approximately 740 reported nonindigenous species (NIS) in the estuarine and near-coastal habitats of the North Pacific and Hawaii. This database was developed by the U.S. Environmental Protection Agency and the U.S. Geological Survey under the auspices of Working Group 21 (Invasive Species) of the North Pacific Marine Science Organization (PCIES). The PICES database contains the data used to generate the “Atlas of Nonindigenous Marine and Estuarine Species in the North Pacific” (Lee and Reusser, 2012; herein referred to as the “Atlas”). The User’s Guide provides instructions on how to use the PICES database as well as metadata for the database and the Atlas. We note that for most users, the Atlas provides a simpler approach to accessing key information on NIS in the PICES countries than the database, though the database does provide additional information on species and sources as well as allowing users to extract information on specific taxa and/or locations (see Section 4). The PICES database also includes species reported from the PICES Rapid Assessment Surveys (RAS). PICES sponsored four rapid assessment surveys with the objective of quickly characterizing the native, non-native, and cryptogenic species present in different locations. Surveys were sponsored in Dalian, China in 2008, Jeju, Korea in 2009, Newport, Oregon, USA in 2010, and Peter the Great Bay, near Vladivostok and Nakhodka, Russia in 2011 ( http://www.pices.int/publications/pices_press/volume19/v19_n1/pp_30-31_Kobe-WS_f.pdf , http://www.pices.int/publications/pices_press/volume20/v20_n1/pp_26-29_RAS-2011.pdf ). The PICES database contains the RAS species that were made available in time for inclusion. Thus, the database does not capture all the species found in these surveys. In addition, much of the information on the RAS species was provided by the experts conducting the survey, and their distributions, environmental requirements, and life history attributes were not evaluated to the same level of detail by the PICES authors as the North Pacific NIS. In lieu of the more extensive review as conduced with the Atlas species, the information on the RAS species needs to be considered preliminary. Additionally, it is important to use the “Map All Distributions” option (see Section 3.6.6) when mapping their distribution or conducting a query. The general reference for the RAS surveys in the PICES database is “PICES Working Group 21, YEAR SURVEY”. The overall goal of both the database and Atlas was to simplify and standardize the dissemination of distributional, habitat, and life history characteristics of near-coastal and estuarine nonindigenous species. This database provides a means of querying these data and displaying the information in a consistent format. The specific classes of information the database captures include: Regional and global ranges of native and nonindigenous near-coastal and estuarine species at different hierarchical spatial scales. Habitat and physiological requirements of near-coastal and estuarine species. Life history characteristics of near-coastal and estuarine species. Invasion history and vectors for nonindigenous species. This standardized and synthesized data in the database and the Atlas provide the basic information needed to address a number of managerial and scientific needs. Thus, users will be able to: Create a baseline on the extent of invasion by region in order to assess new invasions. Use existing geographical patterns of invasion to gain some insights into potential new invaders. Use existing geographical patters of invasion to gain some insights into mechanisms affecting relative invasibility of different areas. Use life history attributes and environmental requirements of the reported nonindigenous species to evaluate traits of invaders. Understand the potential spread of invaders based on their habitat and environmental requirements. Understand importance of different vectors of introduction of nonindigenous species by region. The data in the Atlas of Nonindigenous Marine and Estuarine Species in the North Pacific (Lee and Reusser, 2012) are up-to-date as of June 2012. Updates to the PICES database were made in September 2012.

Report↗
USGS2006

Late Pleistocene outburst flooding from pluvial Lake Alvord into the Owyhee River, Oregon

At least one large, late Pleistocene flood traveled into the Owyhee River as a result of a rise and subsequent outburst from pluvial Lake Alvord in southeastern Oregon. Lake Alvord breached Big Sand Gap in its eastern rim after reaching an elevation of 1292 m, releasing 11.3 km3 of water into the adjacent Coyote Basin as it eroded the Big Sand Gap outlet channel to an elevation of about 1280 m. The outflow filled and then spilled out of Coyote Basin through two outlets at 1278 m and into Crooked Creek drainage, ultimately flowing into the Owyhee and Snake Rivers. Along Crooked Creek, the resulting flood eroded canyons, stripped bedrock surfaces, and deposited numerous boulder bars containing imbricated clasts up to 4.1 m in diameter, some of which are located over 30 m above the present-day channel. Critical depth calculations at Big Sand Gap show that maximum outflow from a 1292- to 1280-m drop in Lake Alvord was ??? 10,000 m3 s- 1. Flooding became confined to a single channel approximately 40 km downstream of Big Sand Gap, where step-backwater calculations show that a much larger peak discharge of 40,000 m3 s- 1 is required to match the highest geologic evidence of the flood in this channel. This inconsistency can be explained by (1) a single 10,000 m3 s- 1 flood that caused at least 13 m of vertical incision in the channel (hence enlarging the channel cross-section); (2) multiple floods of 10,000 m3 s- 1 or less, each producing some incision of the channel; or (3) an earlier flood of 40,000 m3 s- 1 creating the highest flood deposits and crossed drainage divides observed along Crooked Creek drainage, followed by a later 10,000 m3 s- 1 flood associated with the most recent shorelines in Alvord and Coyote Basins. Well-developed shorelines of Lake Alvord at 1280 m and in Coyote Basin at 1278 m suggest that after the initial flood, postflood overflow persisted for an extended period, connecting Alvord and Coyote Basins with the Owyhee River of the Columbia River drainage. Surficial weathering characteristics and planktonic freshwater diatoms in Lake Alvord sediment stratigraphically below Mt. St. Helens set Sg tephra, suggest deep open-basin conditions at ??? 13-14 ka (14C yr) and that the flood and prominent shorelines date to about this time. But geomorphic and sedimentological evidence also show that Alvord and Coyote Basins held older, higher-elevation lakes that may have released earlier floods down Crooked Creek. ?? 2006 Elsevier B.V. All rights reserved.

Geomorphology↗
USGS2021

Late Cenozoic tephrochronology of the Mount Diablo area within the evolving plate-tectonic boundary zone of northern California

We present a tephrochronologic/chronostratigraphic database for the Mount Diablo area and greater San Francisco Bay region that provides a spatial and temporal framework for geologic studies in the region, including stratigraphy, paleogeography, tectonics, quantification of earth surface processes, recurrence of natural hazards, and climate change. We identified and correlated 34 tephra layers within this region using the chemical composition of their volcanic glasses, stratigraphic sequence, and isotopic and other dating techniques. Tephra layers range in age from ca. 65 ka to ca. 29 Ma, as determined by direct radiometric techniques or by correlation to sites where they have been dated. The tephra layers are of Quaternary or Neogene age except for two that are of Oligocene age. We correlated the tephra layers among numerous sites throughout northern California. Source areas of the tephra layers are the Snake River–Yellowstone hotspot trend of northern Nevada, southern Idaho, and western Wyoming; the Nevadaplano caldera complex of central Nevada; the Jemez Mountains–Valles Caldera in northwestern New Mexico; the Southern Nevada volcanic field and related source areas in eastern California and west-central Nevada; the Quien Sabe–Sonoma volcanic centers of the California Coast Ranges; and the young Cascade Range volcanic centers of northeastern California and Oregon.

GSA Memoirs↗