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At least 109 records · Page 6Linked to original sources
USGS2006

Report of the USGS Coastal and Marine Geology Modeling Workshop, Pacific Marine Science Center, Santa Cruz, CA, March 22-23, 2005

A U.S. Geological Survey (USGS) Coastal and Marine Geology (CMG) Modeling Workshop was held to discuss the general topic of coastal modeling, defined broadly to include circulation, waves, sediment transport, water quality, ecology, sediment diagenesis, morphology change, and coastal evolution, on scales ranging from seconds and a few centimeters (individual ripples) to centuries (coastal evolution) and thousands of kilometers (tsunami propagation). The workshop was convened at the suggestion of CMG Program Management to improve communication among modelers and model users, assess modeling-related activities being conducted at the three centers (Florida Integrated Science Center, FISC; Pacific Marine Science Center; PMSC; and Woods Hole Science Center; WHSC), and develop goals, strategies, and plans for future modeling activities. The workshop represents a step toward developing a five-year strategic plan, and was timed to provide input for the FY06 prospectus. The workshop was held at the USGS Pacific Marine Science Center in Santa Cruz on March 22-23, 2005.

Open-File Report↗
USGS2014

Thresholds for protecting Pacific Northwest ecosystems from atmospheric deposition of nitrogen: state of knowledge report

The National Park Service and U.S. Forest Service manage areas in the states of Idaho, Oregon, and Washington – collectively referred to in this report as the Pacific Northwest - that contain significant natural resources and provide many recreational opportunities. The agencies are mandated to protect the air quality and air pollution-sensitive resources on these federal lands. Human activity has greatly increased the amount of nitrogen emitted to the atmosphere, resulting in elevated amounts of nitrogen being deposited in park and forest ecosystems. There is limited information in the Pacific Northwest about the levels of nitrogen that negatively affect natural systems, i.e., the critical loads. The National Park Service and U.S. Forest Service, with scientific input from the U.S. Geological Survey, have developed an approach for accumulating additional nitrogen critical loads information in the Pacific Northwest and using the data in planning and regulatory arenas. As a first step in that process, this report summarizes the current state of knowledge about nitrogen deposition, effects, and critical loads in the region. It also describes ongoing research efforts and identifies and prioritizes additional data needs.

Idaho;Oregon;Washington↗
USGS2020

Rapid geodetic observations of spatiotemporally varying postseismic deformation following the Ridgecrest earthquake sequence: The U.S. Geological Survey response

The U.S. Geological Survey’s geodetic response to the 4–5 July 2019 (Pacific time) Ridgecrest earthquake sequence comprised primarily the installation and/or reoccupation of Global Navigation Satellite System (GNSS) monumentation. Our response focused primarily on the United States’ Navy’s China Lake Naval Air Weapons Station base (NAWSCL). This focus was because much of the surface rupture occurred on the NAWSCL and because of NAWSCL access restrictions only permitting Federal and State of California personnel. In total, we measured or are still measuring at 24 sites, 14 of which were on the NAWSCL and, as of this writing, operational. The majority of sites were set up as continuous stations logging at either 1 sample per second or 1 sample per 15 s. Two stations were recording a 200 m cross‐rupture aperture starting ∼10 hr after the M 6.4 event, and they recorded the coseismic displacements of the M 7.1. Approximately, 1 hr after the M 7.1 event, two new stations were recording a ∼200 m cross‐rupture aperture of the surface rupture. In the days following, we established the rest of the stations ranging to a distance of ∼15 km from the M 7.1 principal rupture trace. The lack of differential displacement across the M 6.4 rupture during the M 7.1 event suggests that it did not reactivate the M 6.4 plane. The lack of differential cross‐fault displacement for both events suggests that rapid shallow afterslip did not occur at those two locations. The postseismic time series from these stations shows centimeters of horizontal displacement over periods of a few months. They record a mixture of fault‐parallel and fault‐normal displacements that, in conjunction with analysis of more spatially complete Interferometric Synthetic Aperture Radar displacement fields, suggest that both poroelastic and afterslip phenomena occur along the M 6.4 and 7.1 rupture planes. Using preliminary data from these and other regional stations, we also explore the Ridgecrest sequence’s effect on regional GNSS time series and the differentiation of long‐term postseismic motions and secular deformation rates. We find that redefining a common‐mode noise filter using different GNSS stations that are assumed to be unaffected by the earthquakes results in small but systematic differences in the regional velocity field estimate.

Seismological Research Letters↗
USGS2025

Developing a probabilistic tsunami hazard assessment framework for Pacific sources: USGS Powell Center meeting summary

Multi-organizational principal investigators formed a U.S. Geological Survey (USGS) Powell Center Working Group (WG), Tsunami Source Standardization for Hazards Mitigation in the United States, to develop a comprehensive series of sources capable of generating tsunamis that could impact U.S. state and territory coastal areas using probabilistic tsunami hazard analysis (PTHA). PTHA results are commonly used to provide consistent tsunami hazard information for use in engineering and risk assessment and, to a lesser extent, hazard response planning. Following an initial weeklong planning meeting in April 2018, designed to establish the WG’s scope, a series of weeklong meetings devoted to aspects of tsunami hazards placed emphasis on assessment of various tsunami sources, including subduction zones in Alaska, the Atlantic and Caribbean, Cascadia, and the Pacific Basin, as well as landslides in Alaska, the Atlantic, and the Caribbean. The final meeting in the series discussed tsunami sources from crustal faults. These meetings, each with a regional geographic focus, were designed to incorporate reviews and feedback from subject matter experts (SMEs) in academia, private industry, and federal, state, and local governmental organizations. Incorporating consensus from SMEs is important because the results derived from the tsunami source models will be used to inform the public about potential hazards from tsunamis related to safety concerns. This paper describes the USGS Powell Center meeting in March 2023, devoted specifically to developing a PTHA for tsunami sources in the Pacific Ocean Basin other than the Alaska–Aleutian and Cascadia subduction zones that were addressed during previous WG meetings.

Environmental & Engineering Geoscience↗
USGS2023

Identifying research in support of the management and control of dreissenid mussels in the western United States

On February 9–10, 2022, the Pacific States Marine Fisheries Commission, U.S. Fish and Wildlife Service, U.S. Geological Survey, and Washington State University hosted a workshop to establish research priorities that support the implementation of action items listed in a current invasive species management plan, the Quagga and Zebra Mussel Action Plan (QZAP) 2.0, that are intended to limit the establishment and spread of quagga and zebra mussels in the western United States. The workshop focus was on developing research priorities for the thematic areas that are addressed in QZAP 2.0: 1) early detection monitoring, 2) prevention and containment, 3) control and management, and 4) rapid response. In addition, research priorities were developed for a fifth thematic area that addressed dreissenid mussel biology. Forty scientists participated in the two-day workshop. Prior to the workshop, participants were asked to review and rank research priorities that were established for a previous version of the QZAP and to offer suggestions on emerging research priorities. During the workshop, subject matter experts presented information describing current knowledge of research and information associated with the thematic areas of early detection monitoring, prevention and containment, rapid response, control and management, and biology in the context of strategies and actions listed in QZAP 2.0. The rankings of previous research priorities and suggestions of emerging priorities were then reviewed, and a revised list of research priorities was formed. The list of research priorities is presented by thematic area.

Management of Biological Invasions↗
USGS2018

James Dwight Dana and John Strong Newberry in the US Pacific Northwest: The roots of American fluvialism

Recognition of the power of rivers to carve landscapes transformed geology and geomorphology in the late nineteenth century. Wide acceptance of this concept—then known as “fluvialism”—owes to many factors and people, several associated with exploration of western North America. Especially famous are the federal geographic and geologic surveys of the US Southwest with John Wesley Powell and Grove Karl Gilbert, which produced key insights regarding river processes. Yet earlier and less-known surveys also engaged young geologists embarking on tremendously influential careers, particularly the 1838–1842 US Exploring Expedition with James Dwight Dana and the 1853–1855 railroad surveys including John Strong Newberry. Informed but little constrained by European and British perspectives on landscape formation, Dana and Newberry built compelling cases for the erosive power of rivers, largely from observations in the US Pacific Northwest. They seeded the insights of the later southwestern surveys, Dana by his writings and station at Yale and his hugely influential Manual of Geology , published in 1863, and Newberry by becoming the first geologist to explore the dramatic river-carved canyons of the Southwest and then a forceful proponent of the federal surveys spotlighting the erosional landscapes. Newberry also gave Gilbert his start as a geologist. Although Dana and Newberry are renowned early American geologists, their geomorphic contributions were overshadowed by the works of Powell, Gilbert, and William Morris Davis. Yet Dana and Newberry were the first ardent American proponents of fluvialism, providing strong roots that in just a few decades transformed western geology, roots nourished in large measure by the geologically fertile landscapes of the US Pacific Northwest.

Journal of Geology↗
USGS2008

Ground water on tropical Pacific Islands— Understanding a vital resource

To a casual observer, tropical Pacific islands seem idyllic. Closer scrutiny reveals that their generally small size makes them particularly vulnerable to economic and environmental stresses imposed by rapidly growing populations, increasing economic development, and global climate change. On these islands, freshwater is one of the most precious resources. Ground water is the main source of drinking water on many islands, and for quite a few islands, it is the only reliable source of water throughout the year. Faced with a growing demand for this valuable resource, and the potential negative effects on its availability and quality from changes in global climate, increasingly sophisticated management approaches will be needed to ensure a dependable supply of freshwater for the residents of these islands. Much scientific information has been collected by the U.S. Geological Survey (USGS) and other organizations about the ground-water resources of tropical Pacific islands. The aim of this Circular is to give members of the public, policymakers, and other stakeholders knowledge that will help ensure that this information can be used to make informed decisions about the management of these life-giving resources. As the demand for freshwater grows, new monitoring and research efforts will be needed to (1) characterize the extent and sustainability of ground-water resources on different tropical Pacific islands, (2) better understand linkages between ground-water discharge and freshwater and nearshore ecosystems, and (3) prepare for the effects of climate change, which will likely include the loss of habitable land and reduced areas for the accumulation of ground water as a result of rising sea levels.

Laura area of Majuro Atoll↗
USGS2024

Developing version 2 of satellite-estimated precipitation monthly reports for selected locations in the Republic of the Marshall Islands

The Republic of the Marshall Islands (RMI; also known as the Marshall Islands) is a nation of more than 30 low-lying atolls and islands, most of which are inhabited, dispersed across an Exclusive Economic Zone over 770,000 square miles in the tropical central north Pacific Ocean. The study objectives and methods were originally presented in U.S. Geological Survey Data Report 1181 and are summarized herein. Monitoring environmental conditions for potential drought risk is challenging in such a dispersed island nation, and current drought hazard products provide generalities regarding conditions on a broad geographic scale. In 2022–23, a team of U.S. Geological Survey scientists, and managers of natural resources and natural hazards in the RMI, used Integrated Multi-satellitE Retrievals for Global Precipitation Measurement satellite estimates of precipitation to develop content and a template for timely monthly reporting of precipitation for 23 inhabited atolls and islands. After a year of report production and user feedback, the team incorporated lessons learned and revised user priorities to update the content and layout of the template. This data report describes the collaboration process and results of revising the report content and layout into version 2 of the monthly satellite-estimated precipitation report.

Data Report↗
USGS2010

Tsunami Preparedness in California (videos)

Tsunamis are a constant threat to the coasts of our world. Although tsunamis are infrequent along the West coast of the United States, it is possible and necessary to prepare for potential tsunami hazards to minimize loss of life and property. Community awareness programs are important, as they strive to create an informed society by providing education and training. These videos about tsunami preparedness in California distinguish between a local tsunami and a distant event and focus on the specific needs of each region. They offer guidelines for correct tsunami response and community preparedness from local emergency managers, first-responders, and leading experts on tsunami hazards and warnings, who have been working on ways of making the tsunami affected regions safer for the people and communities on a long-term basis. These videos were produced by the U.S. Geological Survey (USGS) in cooperation with the California Emergency Management Agency (CalEMA) and Pacific Gas and Electric Company (PG&E).

General Information Product↗
USGS2010

The Limit of Inundation of the September 29, 2009, Tsunami on Tutuila, American Samoa

U.S. Geological Survey scientists investigated the coastal impacts of the September 29, 2009, South Pacific tsunami in Tutuila, American Samoa in October and November 2009, including mapping the alongshore variation in the limit of inundation. Knowing the inundation limit is useful for planning safer coastal development and evacuation routes for future tsunamis and for improving models of tsunami hazards. This report presents field data documenting the limit of inundation at 18 sites around Tutuila collected in the weeks following the tsunami using Differential GPS (DGPS). In total, 15,703 points along inundation lines were mapped. Estimates of DGPS error and uncertainty in interpretation of the inundation line are provided as electronic files that accompany this report.

Open-File Report↗
USGS2016

Geologic map of the Sauvie Island quadrangle, Multnomah and Columbia Counties, Oregon, and Clark County, Washington

Introduction The Sauvie Island 7.5' quadrangle is situated in the Puget-Willamette Lowland northwest of downtown Portland, Oreg. This lowland, which extends from Puget Sound to west-central Oregon, is a complex structural and topographic trough between the Coast Range and the Cascade Range. Since late Eocene time, the Cascade Range has been the locus of a discontinuously active volcanic arc associated with underthrusting of oceanic lithosphere beneath the North American continent along the Cascadia Subduction Zone. The Coast Range, which occupies the fore-arc position within the Cascadia arc-trench system, consists of a complex assemblage of Eocene to Miocene volcanic and marine sedimentary rocks. The Sauvie Island quadrangle lies along the southwest margin of the Portland Basin, a 2,000-km 2 topographic and structural depression. The basin boundary is an abrupt topographic break at the base of the Tualatin Mountains, which separates the Portland and Tualatin Basins. The Tualatin Mountains are underlain by lava flows of the Miocene Columbia River Basalt Group that have been folded into an asymmetric anticline. Oligocene marine sedimentary rocks, not exposed at the surface, are inferred to underlie the basalt flows. The abrupt basin boundary marks the location of the northwest-striking Portland Hills Fault Zone, which is probably an active structure. The Columbia River flows west and north through the Portland Basin at nearly sea level. The Willamette River enters the Columbia near the southeast corner of the map area. Seismic-reflection profiles and lithologic logs of water wells show as much as 550 m of late Miocene and younger sediments in the deepest part of the basin east of the quadrangle. Deposits exposed at the surface consist chiefly of Holocene and late Pleistocene fluvial and eolian sediments and man-made fill. This map contributes to a U.S. Geological Survey program to improve the geologic database for the Portland region of the Pacific Northwest urban corridor. The map and ancillary data will support assessments of seismic risk, ground-failure hazards, and resource availability.

Oregon, Washington↗
USGS1993

National water summary 1990-91: Hydrologic events and stream water quality

National Water Summary 1990-91 Hydrologic Events and Stream Water Quality was planned to complement existing Federal-State water-quality reporting to the U.S. Congress that is required by the Clean Water Act of 1972. This act, formally known as the Federal Water Pollution Control Act Amendments of 1972 (Public Law 92-500), and its amendments in 1977,1979,1980,1981,1983, and 1987, is the principal basis for Federal-State cooperation on maintaining and reporting on water quality in the United States. Under section 305(b) of the Clean Water Act, the States must designate uses for waterbodies, biennially assess whether the waterbodies meet designated uses, and report to the U.S. Environmental Protection Agency (EPA), which in turn summarizes the findings of the State assessments in a biennial National Water Quality Inventory report to the Congress. This volume of the National Water Summary uses a nationally consistent data base and methods of statistical analysis to document stream water quality in the United States, Puerto Rico, and the Western Pacific Islands. As a basis for preparation of this report, the U.S. Geological Survey (uses) created a data base of waterquality data from about 2,900 stream water-quality monitoring stations in the United States (Lanfear, 1993). These data, which were extracted primarily from the uses National Water Information System (NWIS) and supplemented with data from the EPA national data base known as STORET, consisted mostly of water-chemistry and physical-sediment data. About 1,400 of these stations met a criterion, used in this volume for trends analysis of data, of having a period of record that began before water year 1980. (A water year is the period from October 1 through September 30 and is identified by the calendar year at the end of the period.) Inasmuch as the determination of trends requires about 10 years of data, few biological data were suitable for trends analysis because biological indicators of water quality were not being collected extensively by water year 1980. Also, because of the lack of long-term data, an assessment of the water quality of lakes and reservoirs is not included in this National Water Summary . Constituent and waterproperty data were selected from this data base and analyzed with statistical techniques that have been used extensively by the uses to summarize conditions and trends in water quality. (Throughout the remainder of this article, the term "constituent" is used also to represent water properties, such as pH and alkalinity.) Selected results from this analysis are presented graphically, both by State and nationally, in this volume. The data base created for preparation of this volume and the resulting nationally consistent statistical analysis of these data provide a unique opportunity to compare and contrast stream water-quality conditions and trends nationally and State by State. Because of the complexity of water quality and the natural seasonal and diurnal variations in the concentrations of waterquality constituents, the determination of trends in water quality requires a relatively long period of record. Trends in constituent concentrations in the State summaries in this volume were calculated for one or more of four periods water years 1970-89,1975-89,1980- 89, and 1982-89. Unfortunately, few water-quality monitoring stations have periods of record of more than 10 or 15 years, and therefore most analyses in the State summaries were done for 8- or 10-year periods. Although interest in water quality has continued to heighten since passage of the Clean Water Act, funds for support of data-collection programs are limited and data records of many of the constituents now of current concern, especially organic constituents, do not exist or are less than 10-years long; consequently only a modest number of organic constituents are presented in this volume. Discussion of conditions and trends in water quality in this National Water Summary also draw upon information about land use, population, water use, application of agricultural chemicals in rural areas, the siting of industrial facilities, and other ancillary information. Because the results of analysis of a restricted number of constituents are presented in this volume, State 305(b) reports also are cited in the discussion of water quality in each State. The following discussion is an overview of the three parts of this 1990-91 National Water Summary - "Hydrologic Conditions and Water-Related Events, Water Years 1990-91," "Hydrologic Perspectives on Water Issues," and "State Summaries of Stream Water Quality."

Water Supply Paper↗
USGS2009

U.S. Geological Survey (USGS) Western Region: Seabirds coastal and ocean science

From the cold, high Arctic area of Alaska to the warm, tropical Pacific area of Hawai'i, a diverse array of seabird species numbering in the millions of individuals live off the bounty of the Pacific Ocean. Many come to land only to nest and raise their young - these are species supremely adapted for life on the water, whether it be near the coast or hundreds of miles at sea. Those seabirds that reside in the North Pacific year-round are joined each summer by millions of migrant birds that leave the southern hemisphere in winter for better feeding conditions in the north. Seabirds in the Pacific remain one of the great wildlife spectacles on the earth. Yet, seabirds face a number of threats such as oil spills, introduction of predators to their nesting islands, and conflicts with fisheries. State and Federal agencies require increasingly sophisticated information on population dynamics, breeding biology, and feeding ecology to successfully manage these species and their ecosystems. Within the Western Region of the USGS, scientists from the Alaska Science Center (ASC), Western Ecological Research Center (WERC), and Pacific Islands Ecosystems Research Center are leading the way in conducting research on many of these little known species. Their aim is to improve our understanding of seabirds in the Pacific and to provide information to support informed management of the birds and their ecosystems.

Fact Sheet↗
USGS1980

Bibliography of fine-grained siliceous deposits

This bibliography was compiled under the auspices of the International Geologic Correlations Project's (IGCP) Research Group 115, "Siliceous Deposits of the Pacific Region"; IGCP is sponsored by UNESCO and the International Union of Geological Sciences (IUGS). Research Group 115 was originally proposed to IGCP in 1974 by Professor Azuma Iijima, University of Tokyo, and is now headed by James R. Hein, U.S. Geological Survey. Cooperative efforts by 86 members from 17 countries help in accomplishing Research Group 115's objectives of correlating sedimentary processes of siliceous deposits in the Pacific Basin and neighboring geosynclinal areas by means of stratigraphy, sedimentology, geochemisty, and paleontology. These correlations will allow us to estimate the geochemical silica budget in the Earth's crust; to estimate the production of silica in the marine environment through geologic time; to formulate a general rule on sedimentation of siliceous deposits in geosynclines; to increase understanding of the development of circum-Pacific orogenic belts; and to obtain basic methods to evaluate siliceous deposits of economic interest. The group agreed to focus on fine-grained siliceous deposits (cherts, siliceous shales, diatomites, and the like) and to exclude quartz sand deposits and quartzose sandstones.

Open-File Report↗
USGS2003

Hydrologic Resources of Guam

Introduction The U.S. Territory of Guam, which lies in the western Pacific Ocean near latitude 13?28'N and longitude 144?45'E, is the largest (211 mi2) and southernmost of the islands in the Mariana chain. Ground water supplies about 80 percent of the drinking water for the island's 150,000 residents and nearly one million visitors per year. In northern Guam, water is obtained from wells that tap the upper part of a fresh ground-water lens in an aquifer composed mainly of limestone. About 180 wells, nearly all in the north, withdraw about 35 Mgal/d of water with chloride concentrations ranging from 6 to 585 mg/L. In southern Guam, the main source of freshwater is from surface water that runs off the weathered volcanic rocks that are exposed over much of the area. About 9.9 Mgal/d of freshwater is obtained using surface reservoirs. The island's freshwater resources are adequate to meet current (2003) needs, but future demands will eventually be higher. To better understand the hydrology of the island, the U.S. Geological Survey (USGS) entered into a cooperative study with the Water and Environmental Research Institute of the Western Pacific (WERI) at the University of Guam. The objective of the study was to provide a better understanding of the water resources of the island through analysis of data collected by the USGS on Guam. This report provides a description of the general hydrologic principles of the island's ground-water systems, as well as of the rainfall and geology of Guam. Hydrologic data described in the report include water levels, chloride concentrations, and pumpage from ground-water wells and streamflow data from southern Guam.

Water-Resources Investigations Report↗
USGS2004

Geologic Map of the Woodland Quadrangle, Clark and Cowlitz Counties, Washington

The Woodland 7.5' quadrangle is situated in the Puget-Willamette Lowland approximately 50 km north of Portland, Oregon (fig. 1). The lowland, which extends from Puget Sound into west-central Oregon, is a complex structural and topographic trough that lies between the Coast Range and the Cascade Range. Since late Eocene time, the Cascade Range has been the locus of an active volcanic arc associated with underthrusting of oceanic lithosphere beneath the North American continent along the Cascadia Subduction Zone. The Coast Range occupies the forearc position within the Cascadia arc-trench system and consists of a complex assemblage of Eocene to Miocene volcanic and marine sedimentary rocks. The Woodland quadrangle lies at the northern edge of the Portland Basin, a roughly 2000-km2 topographic and structural depression that is the northernmost of several sediment-filled structural basins, which collectively constitute the Willamette Valley segment of the Puget-Willamette Lowland (Beeson and others, 1989; Swanson and others, 1993; Yeats and others, 1996). The Portland Basin is approximately 70 km long and 30 km wide; its long dimension is oriented northwest. Its northern boundary coincides, in part, with the lower Lewis River, which flows westward through the center of the quadrangle. The Lewis drains a large area in the southern Washington Cascade Range, including the southern flank of Mount St. Helens approximately 25 km upstream from the quadrangle, and joins the Columbia River about 6 km south of Woodland (fig. 1). Northwest of Woodland, the Columbia River exits the broad floodplain of the Portland Basin and flows northward through a relatively narrow bedrock valley at an elevation near sea level. The flanks of the Portland Basin consist of Eocene through Miocene volcanic and sedimentary rocks that rise to elevations exceeding 2000 ft (610 m). Seismic-reflection profiles (L.M. Liberty, written commun., 2003) and lithologic logs of water wells (Swanson and others, 1993; Mabey and Madin, 1995) indicate that as much as 550 m of late Miocene and younger sediments have accumulated in the deepest part of the basin near Vancouver. Most of this basin-fill material was carried in from the east by the Columbia River but sediment deposited by streams draining the adjacent highlands are locally important. The Portland Basin has been interpreted as a pull-apart basin located in the releasing stepover between two en echelon, northwest-striking, right-lateral fault zones (Beeson and others, 1985, 1989; Beeson and Tolan, 1990; Yelin and Patton, 1991; Blakely and others, 1995). These fault zones are thought to reflect regional transpression and dextral shear within the forearc in response to oblique subduction of the Pacific Plate along the Cascadia Subduction Zone (Pezzopane and Weldon, 1993; Wells and others, 1998). The southwestern margin of the Portland Basin is a well-defined topographic break along the base of the Tualatin Mountains, an asymmetric anticlinal ridge that is bounded on its northeast flank by the Portland Hills Fault Zone (Balsillie and Benson, 1971; Beeson and others, 1989; Blakely and others, 1995), which is probably an active structure (Wong and others, 2001; Liberty and others, 2003). The nature of the corresponding northeastern margin of the basin is less clear, but a poorly defined and partially buried dextral extensional fault zone has been hypothesized from topography, microseismicity, potential field-anomalies, and reconnaissance geologic mapping (Beeson and others, 1989; Beeson and Tolan, 1990; Yelin and Patton, 1991; Blakely and others, 1995). Another dextral structure may control the north-northwest-trending reach of the Columbia River between Portland and Longview (Blakely and others, 1995; Evarts, 2002; Evarts and others, 2002). This map is a contribution to a U.S. Geological Survey program designed to improve the geologic database for the Portland Basin part of the Pacific Northwest urban corridor,

Scientific Investigations Map↗
USGS1969

The Geologic Story of the Uinta Mountains

The opening of the West after the Civil War greatly stimulated early geologic exploration west of the 100th Meridian. One of the areas first studied, the Uinta Mountains region, gained wide attention as a result of the explorations of three Territorial Surveys, one headed by John Wesley Powell, one by Clarence King, and one by Ferdinand V. Hayden. Completion of the Union Pacific Railroad across southern Wyoming 100 years ago, in 1869, materially assisted geologic exploration, and the railheads at Green River and Rock Springs greatly simplified the outfitting of expeditions into the mountains. The overlap of the Powell, King, and Hayden surveys in the Uinta Mountains led to efforts that were less concerted than competitive and not without acrimony. Many parts of the area were seen by all three parties at almost the same time. Duplication was inevitable, of course, but all three surveys contributed vast quantities of new knowledge to the storehouse of geology, and many now-basic concepts arose from their observations. Powell's area of interest extended mainly southward from the Uinta Mountains to the Grand Canyon, including the boundless plateaus and canyons of southern Utah and northern Arizona. King's survey extended eastward from the High Sierra in California to Cheyenne, Wyoming, and encompassed a swath of country more than 100 miles wide. Hayden's explorations covered an immense region of mountains and basins from Yellowstone Park in Wyoming southeast throughout most of Colorado. Powell first entered the Uinta Mountains in the fall of 1868, having traveled north around the east end of the range from the White River country to Green River, Wyoming, then south over a circuitous route to Flaming Gorge and Browns Park, and finally back to the White River, where he spent the winter. In 1869, after reexamining much of the area visited the previous season, Powell embarked on his famous 'first boat trip' down the Green and Colorado Rivers. This trip was more exploratory than scientific; his second, more scientific trip was made 2 years later. Powell revisited the Uinta Mountains in 1874 and 1875 to complete the studies begun 6 years earlier. His classic 'Report on the Geology of the Eastern Portion of the Uinta Mountains and a Region of Country Adjacent Thereto' was published in 1876. King's survey?officially 'The United States Geological Exploration of the Fortieth Parallel'?is better known simply as the '40th Parallel Survey.' King began working eastward from California in 1867. The Uinta Mountains region, however, was mapped by S. F. Emmons, under the supervision of King, in the summers of 1869 and 1871. Emmons' work was monumental, and although he emphasized in his letter of transmittal to King the exploratory nature of the work?as the formal title of the report indicates?his maps, descriptions, and conclusions reflect a comprehensive understanding of the country and its rocks. The 40th Parallel report contains the best, most complete early descriptions of the Uinta Mountains. It, indeed, is a treasurechest of information and a landmark contribution to the emerging science of geology. Hayden visited the Uinta Mountains in 1870, descending the valley of Henrys Fork to Flaming Gorge in the fall after having earlier examined the higher part of the range to the west. Most of Hayden's observations were cursory, and he repeatedly expressed regret at having insufficient time for more detailed studies. In reference to the area between Clay Basin and Browns Park, he remarked (Hayden, 1871, p. 67) somewhat dryly that 'the geology of this portion of the Uinta range is very complicated and interesting. To have solved the problem to my entire satisfaction would have required a week or two.' Eighty-odd years later I spent several months there?looking at the same rocks. Powell was perhaps more creative?more intuitive?than either King or Hayden, and his breadth of interest in the fields of geology, physiography, ethnology, an

Bulletin↗
USGS2020

Assessment of multi-stressors on compositional turnover of diatom, invertebrate and fish assemblages along an urban gradient in Pacific Northwest streams (USA)

This study is part of the regional stream-quality assessment (RSQA) conducted by the U.S. Geological Survey (USGS) National Water Quality Assessment (NAWQA) project. The purpose of this study is to examine small streams along land-use and stressor gradients at the regional scale and to evaluate the relative importance of instream stressors on diatom, macroinvertebrate, and fish assemblages. In 2015, the RSQA project assessed stream quality in 82 wadeable streams that were selected along an urban land-use gradient in the Pacific Northwest Region (PNW) of the United States. This study evaluates the effects of four major categories of measured instream stressors – flow (i.e. alteration), water quality, habitat, and contaminants (in water and sediment) – on stream biota. We used gradient forest (GF) models to evaluate taxon specific responses to the various stressors for the three biotic assemblages. Results for diatom, invertebrate and fish assemblages showed that several environmental variables including substrate size, dissolved oxygen, and two or more different contaminants were selected in each of the GF models. In general, all three assemblages were negatively associated with any contaminant measures above zero, except the more tolerant taxa in each assemblage, which responded positively to contaminants. Total nitrogen (TN) and total phosphorus (TP) were important in both the diatom and invertebrate GF models but not in the fish models, which were related to temperature and stream flow. TP and TN were the top two variables for diatom GF models and various taxa responded at a range of nutrient concentrations; however, some taxa responded at low concentrations, for example around 0.02 for TP and 0.5 mg/L for TN. In general, the three biotic assemblages responded to multiple stressors following general patterns of known sensitive versus tolerant taxa for each of the biotic groups studied, yet the GF models allow us to explore taxon specific responses. For example, most of the sensitive Ephemeroptera, Plecoptera, Trichoptera invertebrate taxa (EPT) responded negatively when any contaminant increased above zero; yet some taxa such as the tolerant Trichoptera Cheumatopsyche responded positively to contaminants and many of the other stressors. The findings of this study demonstrate the value of using multiple assemblages to monitoring stressor gradients associated with urban stream systems and the importance of evaluating the responses of individual taxa to stressors.

Washington, Oregon↗