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At least 1,135 records · Page 63Linked to original sources
USGS2023

Prediction of the probability of elevated nitrate concentrations at groundwater depths used for drinking-water supply in the Puget Sound basin, Washington, 2004–19

The Puget Sound basin encompasses the 13,700-square-mile area that drains to the Puget Sound and the adjacent marine waters of Washington State. Well more than 4 million people live within the basin, with numbers continuing to increase, who rely on the basin’s natural resources including groundwater. The Puget Sound Partnership was created by a Washington State statute to implement a science-based recovery of the Puget Sound to help address impacts to these resources. As part of the recovery, the partnership developed the Puget Sound Vital Signs as measures of ecosystem health that guide the assessment of progress toward Puget Sound recovery goals. The Puget Sound Partnership Leadership Council adopted a Drinking Water Vital Sign associated with human health and quality of life, recognizing certain indicators as integral to the sustainability of Puget Sound recovery efforts. One such Vital Sign indicator was the vulnerability of groundwater throughout the aquifers of the Puget Sound basin to elevated nitrate concentrations as defined by the probability of exceeding 2 milligrams/liter (mg/L) at a specific location and well depth. The U.S. Geological Survey (USGS) led the effort to characterize groundwater vulnerability. For this study, groundwater vulnerability refers to a probability with which a contaminant applied at or near the land surface can migrate to the aquifer of interest for a given set of land-use practices. Nitrate concentration data were selected for evaluation because elevated nitrate concentrations are typically caused by anthropogenic activities and have been associated with deleterious impacts on human health. To identify groundwater vulnerability to elevated nitrate concentrations, logistic regression was used to relate anthropogenic (human associated) and natural variables to the occurrence of elevated nitrate concentrations in untreated groundwater from large public water supply system wells found within the Washington State Department of Health Sentry database. Variables that were analyzed included well depth, soil hydraulic conductivity, precipitation, population density, fertilizer application amounts, and land-use types. Statistically significant models that predicted the probabilities of groundwater nitrate concentrations greater than 2 mg/L based on the predictor variables were created for the time periods 2000–04, 2005–09, 2010–14, and 2015–19. For all time periods, well depth and a measure of the abundance of urban and agricultural land over or near the well consistently helped explain the vulnerability of the well to elevated nitrate concentrations defined as a probability of exceeding 2 mg/L of nitrate. Precipitation and (or) soil hydraulic conductivity were also important predictor variables in the models. The models for each time period were used to create maps of groundwater vulnerability at 150- and 300-foot depths throughout the Puget Sound basin. As expected, the most vulnerable locations were associated with shallower well depths and increased agriculture and urban land cover. Across all four time periods, groundwater vulnerability throughout the Puget Sound was low, with probabilities of exceeding 2 mg/L concentrations of nitrate at depths at 150 and 300 feet typically less than 50 percent. Results also found a slight decrease in probabilities of elevated nitrate concentrations throughout the basin over time. More specifically, additional statistical tests found that groundwater with probabilities of less than about 60 percent declined from 2000 to 2019 and represented more than 75 percent of the modeled Puget Sound basin aquifer. Wells with greater than 60 percent probability increased over the same time period but represented only about 25 percent of the aquifer. The maps and statistical analysis presented in the study provide valuable and informative evaluation of the vulnerability of groundwater in the Puget Sound basin to elevated nitrate concentrations. The probability maps do not represent measured nitrate concentrations in groundwater, but rather they present the probability that nitrate concentrations exceed 2 mg/L. The models and predictions from this study are a viable indicator for the Puget Sound Partnership’s Healthy Human Population—Drinking Water Vital Sign. The logistic regression modeling approach presented here benefits water managers by allowing them to assess temporal trends in a range of probabilities, explore vulnerability changes as new regional land cover and anthropogenic data are generated, and distinguish vulnerabilities at different depths within the aquifer.

Washington↗
USGS2025

Phase 1 technical implementation plan for the expansion of the ShakeAlert earthquake early warning system to Alaska

Executive Summary The conference report accompanying the fiscal year (FY) 2022 Consolidated Appropriations Act (Public Law 117–103) for the U.S. Department of the Interior and related agencies directed the U.S. Geological Survey (USGS) to “work with the State of Alaska to develop an implementation plan to be completed within two years in order to put ShakeAlert/Earthquake Early Warning in Alaska” (p. 29). Congress included $1 million in the FY 2022 appropriation to conduct this effort. The USGS Earthquake Hazards Program, along with partner organizations, has developed the ShakeAlert earthquake early warning (EEW) system for the West Coast, which currently operates in California, Oregon, and Washington. The purpose of the system and its alert delivery partners is to reduce the impact of earthquakes and save lives and property by delivering ShakeAlert-powered alerts that are transmitted to the public via mass notification technologies, and by providing more detailed data streams to institutional users and commercial service providers to trigger automated, user-specific, protective actions. ShakeAlert was designed in such a way that it could be expanded to other U.S. regions with high earthquake risk, after the build-out of seismic and geodetic networks to support ShakeAlert in a specified region is completed and the necessary funding is secured for long-term operation and maintenance. When an earthquake occurs, seismic waves radiate from the rupturing fault like waves on a pond. It is these waves that people feel as earthquake shaking and that can cause damage to structures. Using networks of ground-motion sensors and sophisticated computer algorithms, ShakeAlert can detect an earthquake seconds after it begins, calculate its location and magnitude, and estimate the resulting intensity of shaking. Early warnings of impending shaking are then sent to people and systems that may experience damaging shaking, allowing them to take appropriate protective actions. Depending on the user’s distance from the earthquake, alerts may be delivered before, during, or after the arrival of strong shaking. There will almost always be a region near the earthquake epicenter where alerts arrive after damaging shaking has begun. The ShakeAlert system updates its ground-motion estimates as an earthquake grows larger. In response to the FY 2022 congressional direction, the USGS worked with the State of Alaska to devise this implementation plan for ShakeAlert expansion to Alaska. The USGS engaged with the Alaska Division of Homeland Security and Emergency Management (DHS&EM) and the Alaska Division of Geological and Geophysical Surveys (DGGS). A cooperative agreement was awarded to the Alaska Earthquake Center (AEC) at the University of Alaska Fairbanks (UAF) for their contributions to the plan and their work coordinating with other networks in Alaska. The USGS engaged with the Alaska Seismic Hazards Safety Commission (ASHSC) throughout the process. The USGS also held a series of Alaska stakeholder engagements. The process of developing the implementation plan was facilitated by contracted staff from Corner Alliance, which is a government consulting firm. This implementation plan describes the details and estimates the costs for a Phase 1 expansion of the ShakeAlert system to Alaska. A geographically limited Phase 1 goal was chosen that covers the highest risk and most populated areas of Alaska. The areas proposed encompass the State’s main population centers and 90 percent of the State’s population. This Phase 1 design is considered very challenging and ambitious from the viewpoint of network operators. The lessons learned if this plan is implemented could be used to consider subsequent phases to expand EEW beyond Phase 1 in Alaska in the future. ShakeAlert is built on the foundation of the sensor networks and data processing infrastructure of the USGS-led Advanced National Seismic System (ANSS). This implementation plan calls for a total of 450 high-quality, real-time EEW-capable ANSS seismic stations in Alaska: 270 new stations, 160 upgraded stations, and 20 existing stations. These seismic station numbers are based on a station spacing of 10 kilometers (km) in urban areas, 20 km in seismic source areas that endanger population centers, and 40 km in other areas. The associated costs also include support for some EEW-capable global navigation satellite system (GNSS) stations, with a focus on improving warnings for large subduction zone earthquakes. For effective EEW, ShakeAlert requires low-latency, high-availability, robust telemetry links to deliver continuous, real-time data from field stations to the data centers. The Alaska data processing hardware infrastructure would follow the general design for fail-safe operation that is used for the ShakeAlert system on the West Coast. The ShakeAlert architecture uses two independent layers: the production layer for earthquake processing and the alert layer to make alerting decisions and serve alerts to users. This implementation plan includes two geographically separated data centers in Alaska, each with two fully independent production and alert layers using the same system design developed for the West Coast. As of March 2024, the ShakeAlert system is at version 3.0.1, with more advanced versions in the development and testing pipeline. ShakeAlert originally used two algorithms to determine the location and magnitude of earthquakes using seismic data. A third algorithm that can calculate very large magnitudes of very large earthquakes with geodetic data was added in March 2024. ShakeAlert publishes several data and alert products to meet the needs of different users. All messages include the location of the earthquake, either as a point or a line, and its magnitude. Ground-shaking estimates are published in two forms, as ground-motion contours and a map grid. Providing adequate warning time for strong shaking (the “target threshold”) requires sending alerts at a threshold lower than that strong shaking level (the “alert threshold”). The thresholds for public alerting in Alaska would be a joint USGS and State decision. To have the greatest benefit, ShakeAlert-powered alerts would be delivered to institutional users and individuals by all practical pathways. The USGS alert layer can support thousands of institutional users and alert redistributors, but the USGS does not have the mission nor the infrastructure and expertise to perform mass notifications to the public or implement automatic actions for end users of the alerts. To meet this need, ShakeAlert recruits private sector “technology enablers” that have the necessary expertise to develop end-user implementations using EEW alerts with the goal of stimulating an EEW industry. Earthquake early warning alerts are useless if people do not know how to respond to them. Although the alert messages include instructions about what to do (drop, cover, and hold on), alerts are more effective if people have been trained in advance. Messages about ShakeAlert’s capabilities, limitations, and benefits could be integrated with existing earthquake education programs, including State-run programs. Therefore, ShakeAlert would coordinate with both public and private partners and stakeholders through various partnerships and agreements to accomplish consistent and ongoing public earthquake hazard education. The estimated capital cost of completing the computing infrastructure and sensor networks for the Phase 1 ShakeAlert expansion to Alaska is approximately $66 million in 2024 dollars. The annual operation and maintenance cost of the completed system is estimated to be $12 million per year in 2024 dollars when fully built out.

Alaska↗
USGS2020

Spatially referenced models of streamflow and nitrogen, phosphorus, and suspended-sediment loads in streams of the Pacific region of the United States

Although spatial information describing the supply and quality of surface water is critical for managing water resources for human uses and for ecological health, monitoring is expensive and cannot typically be done over large scales or in all streams or waterbodies. To address the need for such data, the U.S. Geological Survey developed SPAtially Referenced Regression On Watershed attributes (SPARROW) for the Pacific region of the U.S. for streamflow and three water-quality constituents–total nitrogen, total phosphorus, and suspended sediment, based on a decadal time frame centered on the year 2012. The domain for these models included the Columbia River basin, the Puget Sound, the coastal drainages of Washington, Oregon, and California, and the Central Valley of California. Landscape runoff (represented by the difference between precipitation and evapotranspiration) was the largest source of streamflow, wastewater discharge, and atmospheric deposition were the largest contributors to total nitrogen yield from the Pacific region, wastewater discharge was the largest contributor to total phosphorus yield, and forest land was the largest contributor to suspended-sediment yield. Watersheds with relatively high water yields also generally had relatively high yields of total nitrogen, total phosphorous, and suspended sediment–except where there were large contributions from developed land and wastewater discharge. The data used in this study, including many that improved upon existing national data or were compiled specifically for the Pacific region, characterized the complex hydrologic and water-quality conditions in the region more completely than previous models. By using these new datasets, this investigation was able to account for the complex network of water diversions and transfers, quantify the contribution of nutrients from different sources of livestock manure, discern a signal from unpaved logging roads in the suspended-sediment yields from forested coastal watersheds, show how recent wildfire disturbance influences phosphorus and sediment delivery to streams, and how sediment delivery to streams is also sensitive to the intensity of cattle grazing. The results from this study could complement research and inform water-quality management activities in the Pacific region. Examples might include identifying potentially impaired waterbodies and guiding remediation efforts where impairment has been documented, explaining the spatial patterns in harmful algal blooms, and providing estimates of sediment and nutrient loadings to Pacific coast estuaries where such data are scarce or non-existent.

Pacific Region↗
USGS2012

Ecosystem services valuation to support decisionmaking on public lands—A case study of the San Pedro River watershed, Arizona

This report details the findings of the Bureau of Land Management–U.S. Geological Survey Ecosystem Services Valuation Pilot Study. This project evaluated alternative methods and tools that quantify and value ecosystem services, and it assessed the tools’ readiness for use in the Bureau of Land Management decisionmaking process. We tested these tools on the San Pedro River watershed in northern Sonora, Mexico, and southeast Arizona. The study area includes the San Pedro Riparian National Conservation Area (managed by the Bureau of Land Management), which has been a focal point for conservation activities and scientific research in recent decades. We applied past site-specific primary valuation studies, value transfer, the Wildlife Habitat Benefits Estimation Toolkit, and the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) and Artificial Intelligence for Ecosystem Services (ARIES) models to value locally important ecosystem services for the San Pedro River watershed—water, carbon, biodiversity, and cultural values. We tested these approaches on a series of scenarios to evaluate ecosystem service changes and the ability of the tools to accommodate scenarios. A suite of additional tools were either at too early a stage of development to run, were proprietary, or were place-specific tools inappropriate for application to the San Pedro River watershed. We described the strengths and weaknesses of these additional ecosystem service tools against a series of evaluative criteria related to their usefulness for Bureau of Land Management decisionmaking. Using these tools, we quantified gains or losses of ecosystem services under three categories of scenarios: urban growth, mesquite management, and water augmentation. These results quantify tradeoffs and could be useful for decisionmaking within Bureau of Land Management district or field offices. Results are accompanied by a relatively high level of uncertainty associated with model outputs, valuation methods, and discount rates applied. Further guidance on representing uncertainty and applying uncertain results in decisionmaking would benefit both tool developers and those offices in using ecosystem services to compare management tradeoffs. Decisionmakers and Bureau of Land Management managers at the State-, district-, and field-office level would also benefit from continuing model improvements, training, and guidance on tool use that can be provided by the U.S. Geological Survey, the Bureau of Land Management, and the Department of the Interior. Tradeoffs were identified in the level of effort needed to parameterize and run tools and the amount and quality of information they provide to the decision process. We found the Wildlife Habitat Benefits Estimation Toolkit, Ecosystem Services Review, and United Nations Environment Programme–World Conservation Monitoring Centre Ecosystem Services Toolkit to be immediately feasible for application by the Bureau of Land Management, given proper guidance on their use. It is also feasible for the Bureau of Land Management to use the InVEST model, but in early 2012 the process of parameterizing the model required resources and expertise that are unlikely to be available in most Bureau of Land Management district or field offices. Application of past primary valuation is feasible, but developing new primary-valuation studies is too time consuming for regular application. Value transfer approaches (aside from the Wildlife Habitat Benefits Estimation Toolkit) are best applied carefully on the basis of guidelines described in this report, to reduce transfer error. The ARIES model can provide useful information in regions modeled in the past (Arizona, California, Colorado, and Washington), but it lacks some features that will improve its usability, such as a generalized model that could be applied anywhere in the United States. Eleven other tools described in this report could become useful as the tools more fully develop, in high-profile cases for which additional resources are available for tool application or in case-study regions where place-specific models have already been developed. To improve the value of these tools in decisionmaking, we suggest scientific needs that agencies such as U.S. Geological Survey can help meet—for instance, development and support of data archives. Such archives could greatly reduce resource needs and improve the reliability and consistency of results. Given the rapid state of evolution in the field, periodic follow-up studies on ecosystem services tools would help to ensure that the Bureau of Land Management and other public land management agencies are kept up to date on new tools and features that bring ecosystem services closer to readiness for use in regular decisionmaking.

Arizona;Sonora↗
USGS2012

Simulation of groundwater and surface-water resources and evaluation of water-management alternatives for the Chamokane Creek basin, Stevens County, Washington

A three-dimensional, transient numerical model of groundwater and surface-water flow was constructed for Chamokane Creek basin to better understand the groundwater-flow system and its relation to surface-water resources. The model described in this report can be used as a tool by water-management agencies and other stakeholders to quantitatively evaluate the effects of potential increases in groundwater pumping on groundwater and surface-water resources in the basin. The Chamokane Creek model was constructed using the U.S. Geological Survey (USGS) integrated model, GSFLOW. GSFLOW was developed to simulate coupled groundwater and surface-water resources. The model uses 1,000-foot grid cells that subdivide the model domain by 102 rows and 106 columns. Six hydrogeologic units in the model are represented using eight model layers. Daily precipitation and temperature were spatially distributed and subsequent groundwater recharge was computed within GSFLOW. Streamflows in Chamokane Creek and its major tributaries are simulated in the model by routing streamflow within a stream network that is coupled to the groundwater-flow system. Groundwater pumpage and surface-water diversions and returns specified in the model were derived from monthly and annual pumpage values previously estimated from another component of this study and new data reported by study partners. The model simulation period is water years 1980-2010 (October 1, 1979, to September 30, 2010), but the model was calibrated to the transient conditions for water years 1999-2010 (October 1, 1998, to September 30, 2010). Calibration was completed by using traditional trial-and-error methods and automated parameter-estimation techniques. The model adequately reproduces the measured time-series groundwater levels and daily streamflows. At well observation points, the mean difference between simulated and measured hydraulic heads is 7 feet with a root-mean-square error divided by the total difference in water levels of 4.7 percent. Simulated streamflow was compared to measured streamflow at the USGS streamflow-gaging station-Chamokane Creek below Falls, near Long Lake (12433200). Annual differences between measured and simulated streamflow for the site ranged from -63 to 22 percent. Calibrated model output includes a 31-year estimate of monthly water budget components for the hydrologic system. Five model applications (scenarios) were completed to obtain a better understanding of the relation between groundwater pumping and surface-water resources. The calibrated transient model was used to evaluate: (1) the connection between the upper- and middle-basin groundwater systems, (2) the effect of surface-water and groundwater uses in the middle basin, (3) the cumulative impacts of claims registry use and permit-exempt wells on Chamokane Creek streamflow, (4) the frequency of regulation due to impacted streamflow, and (5) the levels of domestic and stockwater use that can be regulated. The simulation results indicated that streamflow is affected by existing groundwater pumping in the upper and middle basins. Simulated water-management scenarios show streamflow increased relative to historical conditions as groundwater and surface-water withdrawals decreased.

Washington↗
USGS2009

Floods of water and lava in the Columbia River Basin: Analogs for Mars

The Columbia River Basin (CRB) is home to the best studied examples of two of the most spectacular geologic processes on Earth and Mars: flood volcanism and catastrophic water floods. Additionally, features formed by a variety of eolian, glacial, tectonic, and mass-wasting processes can also be seen in the CRB. These terrains provide exceptional terrestrial analogs for the study of similar processes on Mars. This field guide describes four one-day trips out of Moses Lake, Washington, to observe a wide variety of Mars analogs.

Oregon, Washington↗
USGS2020

Landslide disparities, flume discoveries, and Oso despair

Landslide dynamics is the branch of science that seeks to understand the motion of landslides by applying Newton's laws. This memoir focusses on a 40‐year effort to understand motion of highly mobile—and highly lethal—landslides such as debris avalanches and debris flows. A major component of this work entailed development and operation of the U.S. Geological Survey debris flow flume, a unique, large‐scale experimental facility in Oregon. Experiments there yielded new insights that informed development of mathematical models that were aimed not only at explaining landslide dynamics but also at evaluating landslide and debris flow hazards. The most sophisticated of these models, called D‐Claw, found its first practical application during investigations of the 2014 Oso, Washington, landslide disaster. That event provided indelible lessons about the utility and sociology of science in the real world.

Washington↗
USGS2009

Hydrographs Showing Groundwater Level Changes for Selected Wells in the Chambers-Clover Creek Watershed and Vicinity, Pierce County, Washington

Selected groundwater level hydrographs for the Chambers-Clover Creek watershed (CCCW) and vicinity, Washington, are presented in an interactive web-based map to illustrate changes in groundwater levels in and near the CCCW on a monthly and seasonal basis. Hydrographs are linked to points corresponding to the well location on an interactive map of the study area. Groundwater level data and well information from Federal, State, and local agencies were obtained from the U.S. Geological Survey National Water Information System (NWIS), Groundwater Site Inventory (GWSI) System.

Data Series↗
USGS2009

Bathymetry and Near-River Topography of the Naches and Yakima Rivers at Union Gap and Selah Gap, Yakima County, Washington, August 2008

Yakima County is collaborating with the Bureau of Reclamation on a study of the hydraulics and sediment-transport in the lower Naches River and in the Yakima River between Union Gap and Selah Gap in Washington. River bathymetry and topographic data of the river channels are needed for the study to construct hydraulic models. River survey data were available for most of the study area, but river bathymetry and near-river topography were not available for Selah Gap, near the confluence of the Naches and Yakima Rivers, and for Union Gap. In August 2008, the U.S. Geological Survey surveyed the areas where data were not available. If possible, the surveys were made with a boat-mounted, single-beam echo sounder attached to a survey-grade Real-Time Kinematic (RTK) global positioning system (GPS). An RTK GPS rover was used on a walking survey of the river banks, shallow river areas, and river bed areas that were impenetrable to the echo sounder because of high densities of macrophytes. After the data were edited, 95,654 bathymetric points from the boat survey with the echo sounder and 1,069 points from the walking survey with the GPS rover were used in the study. The points covered 4.6 kilometers on the Yakima River and 0.6 kilometers on the Naches River. GPS-surveyed points checked within 0.014 to 0.047 meters in the horizontal direction and -0.036 to 0.078 meters in the vertical direction compared to previously established survey control points

Data Series↗
USGS2007

The Distribution of Submersed Aquatic Vegetation in the Fresh and Oligohaline Tidal Potomac River, 2004

Introduction Submersed aquatic vegetation (SAV) is a critical component of the Potomac River ecosystem. Though SAV provides important habitat for fauna and stabilizes bottom sediment, very dense beds may restrict recreational and commercial navigation. Exotic species of SAV are managed by the Metropolitan Washington Council of Governments Potomac Aquatic Plant Management Program (PAPMP). Selected beds of exotic SAV species that limit navigation are harvested mechanically. The program began in 1986 when approximately 40 acres of plants were harvested from 18 sites (Metropolitan Washington Council of Governments 1987). Monitoring efforts are an effective means of quantifying the distribution and abundance of the exotic species, Hydrilla verticillata (hydrilla) and other SAV species. These annual surveys provide a basis for identifying large-scale changes throughout the ecosystem and allow managers to evaluate the effectiveness of resource management policies based on a reliable scientific foundation. The U.S. Geological Survey (USGS) has monitored the distribution and composition of SAV beds in the fresh and oligohaline (salinity 0.5 to 5) tidal Potomac River since 1978 using transect sampling (1978 to 1981, 1985 to 1987, and 2002) and shoreline surveys (1983 to 2004). Shoreline survey data from the tidal Potomac River are incorporated into the Virginia Institute of Marine Science (VIMS) annual report on SAV distribution in Chesapeake Bay. The VIMS report and methods are available at http://www.vims.edu/bio/sav. Additional publications concerning SAV distribution in the Potomac River can be found at http://water.usgs.gov/nrp/proj.bib/sav/wethome.htm.

Open-File Report↗
USGS1906

The geography and geology of Alaska; a summary of existing knowledge, with a section on climate, and a topographic map and description thereof

Alaska, the largest outlying possession of the United States, is that great land mass forming the northwestern extremity of the North American continent, whose western point is within 60 miles of the Asiatic coast (PI. II). About one-quarter of this area lies within the Arctic Circle, and from the standpoint of geographic position must be regarded as an arctic province; but the southern seaboard, exposed to the warm winds and waters of the Pacific, gives to the entire southern portion of the territory" a comparatively warm climate. It is not generally realized that the range of climate in Alaska is greater than that between Florida and Maine. At the southernmost point of the Pacific coast the mean annual temperature is not far from that of the city of Washington, the winters being warmer and characterized by less snowfall; the Yukon Valley on the other hand has a winter climate similar to that of northern Montana and Dakota; while in the extreme northern part of the territory the meteorologic conditions are invariably arctic. Though as yet only sparsely settled, Alaska's vast area and great resources make it one of the most important possessions of the United States and promise its rapid development. During the years 1890 to 1900 the population increased from 32,052* to 63,592. The mineral output, which in 1890 was valued at less than $800,000, exceeded $9,000,000 in 1904, and the fisheries show a corresponding growth. This rapid development has attracted public attention and led to urgent demand for explorations, surveys, and other investigations. So actively has this work been pushed, both by public and private enterprise, that exact knowledge of the geography, geology, and mineral resources of the interior has made greater strides within the last eight years than during the preceding thirty-one years since the acquisition of Alaska. The facts regarding the geography and geology, scattered as they are through the many books and reports of this period, are not always readily accessible, and the time seems ripe to present them in a summarized form. The topography of Alaska is varied and complex (see PI. I), and it is not easy to present briefly even the salient features. The limited number of pages here devoted to the subject precludes the possibility of detailed treatment, even if the facts were available. Much of the description has been taken from the results attained by other investigators, the writer being personally familiar with only a part of this large province. A list of the publications consulted is appended. The larger geographic features of Alaska are now fairly well known, though the detailed surveys which are demanded by the development of many localities have hardly been begun. Preliminary surveys have been completed of all but three 8 of the larger rivers. The most important mountain ranges have been at least outlined (fig. 3). Only three large areas remain almost entirely unmapped: One in southwestern Alaska, between Cook Inlet and the lower Kuskokwim, and the others in northern Alaska, embracing the Arctic watershed east and west of the Colville River. Nearly all the surveys of the interior, however, have been of a preliminary and exploratory character, and to meet the requirements of exact geography must be followed by more detailed mensuration. Though the coast line has been fairly well known for more than half a century, knowledge of the interior has been gained chiefly within the last two decades. This has not yet found its way into text-books and has too often been entirely ignored by cartographers. If facts are presented which may seem elementary, it is because even well-informed people have been known to harbor misconceptions in regard to the orographic features, climate, and general character of Alaska. Those who read of the perils and privations of winter travel and explorations are apt to picture a region of ice and snow; others, again, who have personal knowledge of the tourist route of southeastern Alaska, regard the whole district as one of rugged mountains and glaciers. In point of fact, glaciers are now nearly limited to the ranges bordering the Pacific and to the two slopes of the Alaska range; and even during the greatest development of glaciers but a small portion of Alaska was under ice (see map, PI. XXII). As a treatise on geography would hardly be complete without some discussion of the climate, meteorologic data have been compiled by Mr. Cleveland Abbe, jr., but the discussion of this does not pretend to be more than a cursory treatment of the subject. The scope of the paper seems to require also a brief summary of the development of geographic knowledge of Alaska. This subject, with its many ramifications, is of fascinating interest and offers a magnificent field for the trained historian. If the accompanying sketch of discovery and exploration awakens any measure of popular interest the writer will feel amply rewarded for having attacked a theme which hardly falls within the scope of his investigations. When this compilation was begun it was intended to be chiefly a description of the topography of Alaska, as illustrated by the accompanying map (PI. XXXIV, in pocket), which was compiled under the direction of the late R. U. Goode. In the course of the work there accumulated much geologic as well as geographic material which seemed worthy of inclusion in the report. As no comprehensive statement of the geology of Alaska has been made since the modern epoch of investigation was begun, an attempt will be made to give a summary of all results achieved. Since the writer has obtained much of his knowledge of the facts from the work of others, he disclaims any pretense of making an entirely original contribution to geologic science. He feels, however, that a personal familiarity with a considerable part of the province, gained during seven consecutive seasons of field work, will justify Mm in presenting conclusions which may in some cases be at variance with those in the reports on which he must draw for his facts. Throughout this report attempt will be made to credit borrowed material to the source from which it is drawn. Where such matter has been obtained entirely from published reports there is no difficulty in so doing; but as regards investigators of the Geological Survey, with whom the writer has collaborated both in field and in office, the case is somewhat different, for it is not always possible to know whether this or that theory originated with the writer or with one of his colleagues. It will, then, perhaps suffice to state that this report could not have been prepared without the explorations and researches of the geologists, F. C. Schrader, Walter C. Mendenhall, Arthur J. Collier, J. E. Spurr, and Arthur C. Spencer; and the surveys of the topographers, T. G. Gerdine, D. C. Witherspoon, D. L. Reaburn, W. J. Peters, and E. C. Barnard. Each of these men, in the course of from two to six years of field work, has made important contributions to the knowledge of the geography and geology of Alaska, and not all of these results have yet been put in print. In the last season (1903) L. M. Prindle, C. W. Wright, Arthur Hollick, G. C. Martin, F. L. Hess, and Fred H. Moffit have carried on geologic work in Alaska, and the writer has made use of their work now in course of publication. He has also been fortunate in having access to the manuscript reports of Walter C. Mendenhall and F. C. Schrader on the Copper River basin, to which references will be made. The matter here presented should be credited in a measure to all of these investigators, but for many of the theories advanced the writer alone is responsible. As this manuscript goes to press there has been opportunity to incorporate some of the results of the field work of 1904. As far as possible these have been embodied in the text, but in some instances it has been found advisable to add them only as footnotes. During the past summer F. E. and C. W. Wright extended the geologic reconnaissance in southeastern Alaska. In southwestern Alaska G. C. Martin and T. W. Stanton have determined the general Mesozoic section, while F. H. Moffit has made a reconnaissance of the northern part of the Kenai Peninsula. A. J. Collier has mapped the geology of the Cape Lisburne region, and L. M. Prindle and F. L. Hess have made contributions to the knowledge of the metamorphic terranes of the Yukon-Tanana district. It is the writer's purpose to describe in nontechnical language the larger geographic features and discuss their relation as far as the data available will permit. In the treatment of the geology, however, less effort will be made to make the matter acceptable to the lay reader. It is hoped, however, that a brief summary of the salient features of the geologic history' may be not without interest to the general public. If this paper serves in some measure to dispel the popular fallacies regarding Alaska and to disseminate more accurate knowledge of its geographic and geologic features, the purpose of its publication will be accomplished.

Alaska↗
USGS2005

Simulating the evolution of coastal morphology and stratigraphy with a new morphological-behaviour model (GEOMBEST)

A new morphological-behaviour model is used to simulate evolution of coastal morphology associated with cross-shore translations of the shoreface, barrier, and estuary. The model encapsulates qualitative principles drawn from established geological concepts that are parameterized to provide quantitative predictions of morphological change on geological time scales (order 10 3 years), as well as shorter time scales applicable for long-term coastal management (order 101 to 102 years). Changes in sea level, and sediment volume within the shoreface, barrier, and estuary, drive the model behaviour. Further parameters, defining substrate erodibility, sediment composition, and time-dependent shoreface response, constrain the evolution of the shoreface towards an equilibrium profile. Results from numerical experiments are presented for the low-gradient autochthonous setting of North Carolina and the steep allochthonous setting of the Washington shelf. Simulations in the Currituck region of North Carolina examined the influence of sediment supply, substrate composition, and substrate erodibility on barrier transgression. Results demonstrate that the presence of a lithified substrate reduces the rate of barrier transgression compared to scenarios where an erodible, sand-rich substrate exists. Simulations of the Washington coast, 20 km north of the Columbia River, confirmed that the model can reproduce complex stratigraphy involving regressive and transgressive phases of coastal evolution. Results suggest that the first major addition of sediment to the shelf occurred around 12 900 years ago and resulted from the rapid addition of sediment volume from the Columbia River attributed to the Missoula floods. This was followed by a period where little or no sediment was added (12 400-9100 BP) and a third period when most sediment was added to the shelf (9100 BP to present) from the Columbia River. Comparing results from each setting demonstrates an indirect control that substrate slope has on shoreface transgression rates. Shoreface transgression is shown to be sensitive to the rate of estuarine sedimentation, with the sensitivity increasing as substrate slope decreases.

North Carolina↗
USGS1912

Pawpaw-Hancock folio, Maryland-West Virginia-Pennsylvania

The Pawpaw and Hancock quadrangles embrace parts of eastern West Virginia, western Maryland, and southern Pennsylvania between parallels 39° 30' abd 39° 45' and meridians 78° and 78° 30', and contain 460 square miles. (See fig. 1.) Parts of eight counties are included in the area, Morgan, Berkeley, and Hampshire in West Virginia, Washington and Allegany in Maryland, and Bedford, Fulton, and Franklin in Pennsylvania. Hancock, Md., the the largest town in the area, Pawpaw, Great Cacapon, and Berkeley Springs, W. Va., being next in importance.

Maryland, Pennsylvania, West Virginia↗
USGS1977

Pleistocene fishes from Alameda County, California

Six types of freshwater fishes were recovered from an early Pleistocene (Irvingtonian) locality on the east side of San Francisco Bay, Alameda County, Calif. The fauna includes one centrarchid, one salmonid, three cyprinids, and one catostomid. The fauna indicates fluvial and slow-moving or lacustrine aquatic environments. One of the cyprinids and the catostomid are assigned to provisional genera because of the inadequate amount of material available for study and the obvious differences between these fossils and known fossil or recent fishes. They are new additions to the Pleistocene fish fauna of California. Paleogeographic distribution of some of these fishes indicates former fluvial or lacustrine connections between Utah, Idaho, Oregon, Washington, Nevada, and California. The Pliocene and Pleistocene fossil fish faunas indicate the widespread occurrence of genera now endemic to California. A similar picture is presented by the molluscan evidence.

California↗
USGS1976

Uranium and trace elements in stream sediments as an exploration tool

More than 45 trace elements have been reported in anomalous amounts in the uranium ores. The specific suite of elements associated with any one uranium deposit varies according to deposit type and geologic province. The primary geochemical halo of uranium and associated trace elements in the host rock, together with secondary dispersion halo in soils and alluvium, offers a potential geochemical exploration target. Sediment from streams near low-grade uranium occurrences in arkosic sandstone of the Denver basin, Colorado, and sediment from streams in the igneous and metamorphic terrace near the Midnite mine of eastern Washington have been analyzed for acid-extractable U, Cu,Pb, Zn, Ni, Co, Fe, Mn, Mo, Cd, Cr, Ag, V, and Se, and for total Fe, Mn, Hg, As, and organic C. The -80 mesh fraction of the alluvium downstream from a small uraniferous limonite occurrence in the Denver basin shows anomalous concentrations of U, Pb, As, Ni, Mo, V, Zn, and Se. Anomalous concentrations of U persist farther downstream (as much as 1,000 m) than any of the trace elements. In another stream system southeast of Denver, above-background levels of U, Pb, As, Zn, V, Fe, and Mn occur near a uranium anomaly (defined by other methods) which has no surface mineralization. In the Midnite mine area, sediments of streams draining prospect areas showed anomalous concentrations of uranium (as much as 10 times background), but no accompanying anomalous trace-element concentrations, although analyses of Midnite mine ores show that a broad suite of trace elements are associated with uranium.

Open-File Report↗
USGS2011

Hydrogeologic framework of the Johns Creek subbasin and vicinity, Mason County, Washington

This report describes the hydrogeologic framework of the groundwater-flow system in the Johns Creek subbasin and vicinity. The study area covers 97 square miles in southeastern Mason County, Washington, and includes the Johns Creek subbasin, which drains an area of about 11 square miles. The study area extends beyond the Johns Creek subbasin to include major hydrologic features that could be used as regional groundwater-flow model boundaries. The subbasin is underlain by a thick sequence of unconsolidated Quaternary glacial and interglacial deposits, which overlie Tertiary igneous and sedimentary bedrock units. Geologic units were grouped into eight hydrogeologic units consisting of aquifers, confining units, undifferentiated deposits, and an underlying bedrock unit. A surficial hydrogeologic map was developed and used with lithologic information from 200 drillers' logs to construct 4 hydrogeologic sections, and unit extent and thickness maps.

Scientific Investigations Report↗
USGS2001

Holocene geomagnetic secular variation recorded by volcanic deposits at Mount St. Helens, Washington

A compilation of paleomagnetic data from volcanic deposits of Mount St. Helens is presented in this report. The database is used to determine signature paleomagnetic directions of products from its Holocene eruptive events, to assign sampled units to their proper eruptive period, and to begin the assembly of a much larger database of paleomagnetic directions from Holocene volcanic rocks in western North America. The paleomagnetic results from Mount St. Helens are mostly of high quality, and generally agree with the division of its volcanic deposits into eruptive episodes based on previous geologic mapping and radiocarbon dates. The Muddy River andesite's paleomagnetic direction, however, indicates that it is more likely part of the Pine Creek eruptive period rather than the Castle Creek period. In addition, the Two-Fingers andesite flow is more likely part of the Middle Kalama eruptive period and not part of the Goat Rocks period. The paleomagnetic data from Mount St. Helens and Mount Hood document variation in the geomagnetic field's pole position over the last ~2,500 years. A distinct feature of the new paleosecular variation (PSV) record, similar to the Fish Lake record (Oregon), indicates a sudden change from rapid clockwise movement of the pole about the Earth's spin axis to relatively slow counterclockwise movement at ???800 to 900 years B.P.

Bulletin of Volcanology↗
USGS1987

Natural-field and very low-frequency tipper profile interpretation of contacts

Anomalous vertical magnetic field (tipper) profiles acquired using natural or very low-frequency (VLF) radio transmitter sources can be interpreted simply and rapidly for a number of geologic settings. The relations between computed numerical models, and outcropping dipping and buried vertical contacts are presented here in a series of interpretation charts. Use of the tipper phase in the analysis minimizes the effect of transmitter azimuth in the VLF case.Two examples illustrate the application to field data. An audiofrequency natural-field tipper profile over a conductive bed in a north-central Washington State metasedimentary sequence demonstrates the interpretation procedure for a dipping contact. VLF profiles over covered basement faults in Ontario demonstrate the application for a buried vertical contact. In both cases the quick results are in agreement with the much more laborious trial-and-error matching to two-dimensional models.

Geophysics↗