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Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

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At least 523 records · Page 29Linked to original sources
USGS1989

Regional crustal structure and tectonics of the Pacific Coastal States: California, Oregon, and Washington

The Pacific Coastal States form a complex geologic environment in which the crust and lithosphere have been continuously reworked. We divide the region tectonically into the southern transform regime of the San Andreas fault and the northern subduction regime, and summarize the geophysical framework with contour maps of crustal thickness, lithospheric and seismicity cross sections, and results from site-specific geophysical studies. The uniformity of crustal thickness (30 ± 2 km) in southern California is remarkable, and appears to be primarily the result of crustal extension in the Mojave Desert and ductile shear of the lower crust along the plate transform boundary. Southern California seismicity defines a broad zone of deformation that extends from the Borderland to the Mojave Desert (about 300 km). The geophysical framework of central and northern California records magmatism and accretion associated with the Mesozoic and Cenozoic subduction, late Cenozoic transform faulting, and in the Basin and Range to the east, extension. The crust thickens from about 20 km at the coast to as much as 55 km in the Sierra Nevada, and thins to about 30 km in the Basin and Range. Cross sections of the crust show that seismic velocities and densities vary significantly over short distances perpendicular to the coast, reflecting processes that include the accretion of oceanic sediments and igneous crust, and significant lateral motion of crustal blocks. Maximum hypocentral depths in central California become deeper as the crust thickens to the west, but seismicity is low beneath the Great Valley and Sierra Nevada, which together appear to form a relatively undeforming block. The lower crust of the Pacific Coastal States has a high average seismic velocity (6.7 km/sec or greater), which probably is the product of tectonic underplating of oceanic crust and/or magmatic underplating by a basaltic melt.

California, Oregon, Washington↗
USGS1985

Hydrologic factors affecting lake-level fluctuations in Big Marine Lake, Washington County, Minnesota

A study by the U.S. Geological Survey from 1981 through 1984, in cooperation with the Carnelian-Marine Watershed District and the Minnesota Department of Natural Resources, investigated the causes of large lake-level fluctuations at Big Marine Lake. Historic records document that Big Marine Lake has changed substantially in surface area during the period 1847 through 1983; the maximum lake-surface area was 2,300 acres in 1847, and the minimum lake-surface area was 890 acres in 1938. A change in lake level of about 11 feet caused these changes in surface area. Serious flooding of lake-shore properties has occurred in recent years because residential development commonly took place during periods of relatively low-lake level during the 1950's and 1960's. Evaporation from the lake was estimated to be approximately equal to incident precipitation on the lake surface on an annual basis. Big Marine Lake does not have a surface-water inlet, and the outlet from the lake is at an elevation well above the stage at which lake-shore property is flooded. Hydrogeologic and geochemical data collected during the study show that (1) fluctuation of water levels at Big Marine Lake is controlled primarily by ground-water discharge to and seepage from the lake, (2) water in the drift aquifer and water in the lake are chemically similar, and (3) changes in the potentiometric surface of the bedrock aquifer have minor effects on changes in lake level. Long-term trends in cumulative departure from mean annual precipitation suggest that recharge to the drift aquifer in the area has been increasing since the 1940's. The increase in precipitation and recharge corresponds to the observed rise in lake level since 1965 when regular lake-level measurements began. Fluctuations in lake level in the future will depend on changes in recharge to the drift and bedrock aquifers, which is directly related to changes in long-term precipitation patterns.

Minnesota↗
USGS2007

Ground-Water Flow Model for the Spokane Valley-Rathdrum Prairie Aquifer, Spokane County, Washington, and Bonner and Kootenai Counties, Idaho

This report presents a computer model of ground-water flow in the Spokane Valley-Rathdrum Prairie (SVRP) aquifer in Spokane County, Washington, and Bonner and Kootenai Counties, Idaho. The aquifer is the sole source of drinking water for more than 500,000 residents in the area. In response to the concerns about the impacts of increased ground-water withdrawals resulting from recent and projected urban growth, a comprehensive study was initiated by the Idaho Department of Water Resources, the Washington Department of Ecology, and the U.S. Geological Survey to improve the understanding of ground-water flow in the aquifer and of the interaction between ground water and surface water. The ground-water flow model presented in this report is one component of this comprehensive study. The primary purpose of the model is to serve as a tool for analyzing aquifer inflows and outflows, simulating the effects of future changes in ground-water withdrawals from the aquifer, and evaluating aquifer management strategies. The scale of the model and the level of detail are intended for analysis of aquifer-wide water-supply issues. The SVRP aquifer model was developed by the Modeling Team formed within the comprehensive study. The Modeling Team consisted of staff and personnel working under contract with the Idaho Department of Water Resources, personnel working under contract with the Washington Department of Ecology, and staff of the U.S. Geological Survey. To arrive at a final model that has the endorsement of all team members, decisions on modeling approach, methodology, assumptions, and interpretations were reached by consensus. The ground-water flow model MODFLOW-2000 was used to simulate ground-water flow in the SVPR aquifer. The finite-difference model grid consists of 172 rows, 256 columns, and 3 layers. Ground-water flow was simulated from September 1990 through September 2005 using 181 stress periods of 1 month each. The areal extent of the model encompasses an area of approximately 326 square miles. For the most part, the model extent coincides with the 2005 revised extent of the Spokane Valley-Rathdrum Prairie aquifer as defined in a previous report. However, the model excludes Spirit and Hoodoo Valleys because of uncertainties about the ground-water flow directions in those valleys and the degree of hydraulic connection between the valleys and northern Rathdrum Prairie. The SVRP aquifer is considered to be a single hydrogeologic unit except in Hillyard Trough and the Little Spokane River Arm. In those areas, a continuous clay layer divides the aquifer into an upper, unconfined unit and a lower, confined unit. The model includes all known components of inflows to and outflows from the aquifer. Inflows to the SVRP aquifer include (1) recharge from precipitation, (2) inflows from tributary basins and adjacent uplands, (3) subsurface seepage and surface overflows from lakes that border the aquifer, (4) flow from losing segments of the Spokane River to the aquifer, (5) return percolation from irrigation, and (6) effluent from septic systems. Outflows from the SVRP aquifer include (1) ground-water withdrawals from wells, (2) flow from the aquifer to gaining segments of the Spokane River, (3) aquifer discharge to the Little Spokane River, and (4) subsurface outflow from the lower unit at the western limit of the model area near Long Lake. These inflow and outflow components are represented in the model by using MODFLOW-2000 packages. The parameter-estimation program PEST was used to calibrate the SVRP aquifer model. PEST implements a nonlinear least-squares regression method to estimate model parameters so that the differences between measured and simulated quantities are minimized with respect to an optimal criterion. Calibration data include 1,573 measurements of water levels and 313 measurements of streamflow gains and losses along segments of the Spokane and Little Spokane Rivers. Model parameters estimated during calib

Scientific Investigations Report↗
USGS1974

Chemical analyses of Red Sea sediments

One of the prime motives for exploring the deeper subsurface sediments of the Red Sea floor was to gain information on the geochemical systems controlling the hot brine-metalliferous deposits. Accordingly, a strong effort was made to provide both shipboard and laboratory means of analysis of the recovered phases. Shipboard spectrographic analyses (semiquantitative) provided both detailed surveys of chemical properties of the cores and the ability to analyze small subsamples and separated particles such as pyrite, sphalerite, organisms, and similar minute objects. Over 5000 such analyses are provided in Tables 1 to 5. Some supplementary data provided by subsequent analyses for K, Zn, and Ag in the Denver field laboratories of the U. S. Geological Survey have been added to the tables. A second body of data is provided in Table 6, which gives quantitative data on major and minor constituents, performed by the Washington analytical laboratories of the U. S. Geological Survey. A third group of analyses are partial analyses on evaporitic rocks (anhydrite and rock salt) (Table 18, in Manheim Chapter 38, this volume). In addition to the above, a number of the collaborating laboratories are providing more specific chemical data on special phases and constituents of the Red Sea materials. Most of these data are included in chapters in the Geochemical section of this volume. The significance of the data is discussed in Manheim (Chapter 38, this volume) and in the respective reports of shipboard workers and cooperating share laboratories.

Initial reports of the Deep Sea Drilling Project↗
USGS2019

Extreme coastal water level in Washington state: Guidance to support sea level rise planning

This document provides guidelines for assessing exposure to future coastal flooding during extreme coastal water level events – whether these are due to tides, surge, wave run-up, or, more likely, a combination of the three. These guidelines provide information about the current and future magnitude of extreme coastal water levels across Washington State and the underlying processes that influence them. This information is intended to be combined with sea level projections to assess future exposure to coastal flooding along Washington’s coastline. Although the results of our analyses can be combined with any available sea level projections, this report is intended as a companion to the localized sea level rise projections (Miller et al., 2018) developed as part of the Washington Coastal Resilience Project. The Washington Coastal Resilience Project was a three-year effort to rapidly increase the state’s capacity to prepare for sea level rise. The project aimed to improve risk projections, provide better guidelines for land use planners and strengthen capital investment programs for coastal restoration and infrastructure. Partners in the Washington Coastal Resilience Project included Washington Sea Grant, Washington Department of Ecology, Island County, King County, NOAA Office for Coastal Management, Pacific Northwest National Laboratory, Padilla Bay National Estuary Research Reserve, The City of Tacoma, The Nature Conservancy, U.S. Geological Survey, University of Oregon, University of Washington Climate Impacts Group, University of Washington Department of Earth and Space Sciences, Washington Department of Fish and Wildlife and Western Washington University. The 2018 sea level projections are described in an accompanying technical report, along with a review of the science related to sea level rise (Miller et al., 2018). The report and all associated supporting information are available on the Washington Coastal Hazards Resilience Network website (http://www.wacoastalnetwork.com/).

Washington↗
USGS2022

Geologic field-trip guide to volcanism and its interaction with snow and ice at Mount Rainier, Washington

Mount Rainier is the Pacific Northwest’s iconic volcano. At 4,393 meters and situated in the south-central Cascade Range of Washington State, it towers over cities of the Puget Lowland. As the highest summit in the Cascade Range, Mount Rainier hosts 26 glaciers and numerous permanent snow fields covering 87 square kilometers and having a snow and ice volume of about 3.8 cubic kilometers. It remains by far the most heavily glacier-clad mountain in the conterminous United States despite having lost about 14 percent of its ice volume between 1970 and 2008. Five major rivers head at Mount Rainier—the White, Carbon, Puyallup, Nisqually, and Cowlitz Rivers. Because Mount Rainier is situated west of the Cascade Range crest, all of these rivers eventually turn and drain westward. The Puget Lowland, situated west to northwest of Mount Rainier, is the Pacific Northwest’s most densely populated area, including Seattle, Tacoma, and Olympia. The Puget Lowland is now home to a population of more than 4.5 million and a vibrant economy. Mount Rainier is one of the most hazardous volcanoes in the United States, not so much because of its explosivity, but rather because of its frequent eruptions, its propensity to produce voluminous far-traveled lahars, and its proximity to large population centers of the Puget Lowland. Steep-sided, glacially carved valleys serve as lahar conduits, and even mild eruptions commonly produced large lahars that traveled into areas now populated by hundreds of thousands of people. This guide describes a five-day field trip to view the geology of Mount Rainier as it relates to volcanism and its interaction with snow and ice. Day 1 will focus on lahars in the White River valley. We will drive to Enumclaw, Washington, to begin the day then work our way back upvalley toward Mount Rainier. Day 2 concentrates on geology of the Sunrise-Glacier Basin area within Mount Rainier National Park. As part of day 2 activities, we will hike about 10 miles from Sunrise to the top of Burroughs Mountain, down into Glacier Basin, and be picked up at White River Campground. On day 3 we will pack up and move to Paradise, stopping to examine geology along Stevens Canyon Road. We will hike from Paradise along the Golden Gate Trail and eventually eastward to the former Paradise Ice Caves area (the ice caves have melted out). Day 4 involves hiking from Comet Falls trailhead to Mildred Point and return (~7 miles; 11 km), examining geology along the way. During the first half of day 5, we will visit sites on the south side of Mount Rainier to study lahar deposits, then return to the tour origin.

Washington↗
USGS1997

Measuring flood discharge in unstable stream channels using ground-penetrating radar

Field experiments were conducted to test the ability of ground-penetrating radar (GPR) to measure stream-channel cross sections at high flows without the necessity of placing instruments in the water. Experiments were conducted at four U.S. Geological Survey gaging stations in southwest Washington State. With the GPR antenna suspended above the water surface from a bridge or cableway, traverses were made across stream channels to collect radar profile plots of the streambed. Subsequent measurements of water depth were made using conventional depth-measuring equipment (weight and tape) and were used to calculate radar signal velocities. Other streamflow-parameter data were collected to examine their relation to radar signal velocity and to clarity of streambed definition. These initial tests indicate that GPR is capable of producing a reasonably accurate (±20%) stream-channel profile and discharge far more quickly than conventional stream-gaging procedures, while avoiding the problems and hazards associated with placing instruments in the water.

Geology↗
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↗