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USGS1947

Electrochemical stabilization as a means of preventing ground failure in railroads

Laboratory and field data on electrochemical stabilization of clays, by three Russian authors, are here presented in translation. Abstracts of the Russian papers were published in May 1947 issue of the Engineering News Record (pp. 100-101). There exists also a small body of literature, in German and English, dealing with the electrochemical stabilization and related subjects. Elements of the electrochemical process were patented by Casagrande in Germany, shortly before the last war. Results of the Russians and of others, including the German patent, appear to be sound and interesting accordingly. Mechanism of the electrochemical stabilization, however, appears to be surmised rather than established. Unless the mechanism of such stabilization is understood in detail, little progress may be expected in field applications of the electrochemical method. Electroosmosis, a poorly reversible coagulation of the soil colloids, and introduction of exchangeable aluminum into the clay complex have been given credit for the ground-stabilizing effects of direct electrical current. Much remains to be done, as the reader may see, in developing further the theory of the method. A critical study is indicated, in this connection, by agencies or individuals qualified and equipped for basic research in soil physics. Optimum schedules for field treatments need be ascertained with particular care, to suit any given kind of material and environment. A wide range of variation in such schedules, is most certainly to be encountered in dealing with materials as diverse in their composition and properties as are clays. Any generalization on relationships between soil, electrolytes, moisture, and current could be premature if based on the Russian work alone. Stabilization of ground is a major engineering geologic problem of national interest. Needless to say, perhaps, that failures are to be expected, in laboratory and in the field, in this as well as in any other kind of research. To minimize probabilities of such failures, it may be recommended that investigators develop the electrochemical stabilization problem not merely against the relatively narrow background of soil mechanics, but with a certain feeling for geology, mineralogy, pedology, soil physics, and soil chemistry.

Open-File Report↗

USGS2013

USGS Nonindigenous Aquatic Species database with a focus on the introduced fishes of the lower Tennessee and Cumberland drainages

The Nonindigenous Aquatic Species (NAS) database (http://nas.er.usgs.gov) functions as a national repository and clearinghouse for occurrence data for introduced species within the United States. Included is locality information on over 1,100 species of vertebrates, invertebrates, and vascular plants introduced as early as 1850. Taxa include foreign (exotic) species and species native to North America that have been transported outside of their natural range. Locality data are obtained from published and unpublished literature, state, federal and local monitoring programs, museum accessions, on-line databases, websites, professional communications and on-line reporting forms. The NAS web site provides immediate access to new occurrence records through a real-time interface with the NAS database. Visitors to the web site are presented with a set of pre-defined queries that generate lists of species according to state or hydrologic basin of interest. Fact sheets, distribution maps, and information on new occurrences are updated as new records and information become available. The NAS database allows resource managers to learn of new introductions reported in their region or nearby regions, improving response time. Conversely, managers are encouraged to report their observations of new occurrences to the NAS database so information can be disseminated to other managers, researchers, and the public. In May 2004, the NAS database incorporated an Alert System to notify registered users of new introductions as part of a national early detection/rapid response system. Users can register to receive alerts based on geographic or taxonomic criteria. The NAS database was used to identify 23 fish species introduced into the lower Tennessee and Cumberland drainages. Most of these are sport fish stocked to support fisheries, but the list also includes accidental and illegal introductions such as Asian Carps, clupeids, various species popular in the aquarium trade, and Atlantic Needlefish ( Strongylura marina ) that was introduced via the newly-constructed Tennessee-Tombigbee Canal.

Cumberland River;Tennessee River↗

USGS1986

Alaska goose populations: Past, present and future

Many people think Alaska remains a pristine wilderness and that wildlife populations are still at prehistoric levels. This very likely is not true for the 11 species and subspecies of geese that nest in Alaska. Large, widely dispersed populations of geese were observed near the turn of the century. Even in the early 1970s, it was estimated that Alaskan habitats were used by 915,000 nesting and 100,000 additional migrating geese each year (King and Lensink 1971). Since then the Alaskan populations of most of these species have declined, some to dramatically low levels (Raveling 1984), even though habitats within the state have remained largely unaltered by man. The U.S. has treaties with Canada, Mexico, Japan and the Soviet Union to protect geese and other shared migratory birds, confirming international concern for the welfare of this resource. Cooperative research on Alaskan geese during the past several decades has given understanding of their migration corridors, staging and wintering habitats, and the principle places where they are hunted, thereby providing information needed to develop effective management plans. The only attempt to re-introduce geese in Alaska has been in the Aleutian Islands. Other opportunities exist. It is our intent here to: (1) review the historic and current status and important habitats of geese that occur in Alaska; (2) identify existing and potential threats to these populations; and (3) offer alternative management approaches for geese in Alaska.

Alaska↗

USGS2019

Modelling development of riparian ranchlands using ecosystem services at the Aravaipa Watershed, SE Arizona

This paper describes how subdivision and development of rangelands within a remote and celebrated semiarid watershed near the US-Mexico border might affect multiple ecohydrological services provided, such as recharge of the aquifer, water and sediment yield, water quality, flow rates and downstream cultural and natural resources. Specifically, we apply an uncalibrated watershed model and land-change forecasting scenario to consider the potential effects of converting rangelands to housing developments and document potential changes in hydrological ecosystem services. A new method to incorporate weather data in watershed modelling is introduced. Results of introducing residential development in this fragile arid environment portray changes in the water budget, including increases in surface-water runoff, water yield, and total sediment loading. Our findings also predict slight reductions in lateral soil water, a component of the water budget that is increasingly becoming recognized as critical to maintaining water availability in arid regions. We discuss how the proposed development on shrub/scrub rangelands could threaten to sever imperative ecohydrological interactions and impact multiple ecosystem services. This research highlights rangeland management issues important for the protection of open-space, economic valuation of rangeland ecosystem services, conservation easements, and incentives to develop markets for these.

Arizona↗

USGS1989

Summary of the U.S. Geological Survey and U.S. Bureau of Land Management national coal-hydrology program, 1974-84

During the decade 1974-84, the U.S. Geological Survey and the U.S. Bureau of Land Management cooperated on investigations to collect information and to study hydrologic processes related to development and mining of federally owned coal. In addition, the U.S. Geological Survey conducted similar investigations related to nonfederally owned coal. As a result of these nationwide investigations, a large quantity of hydrologic information and data has been collected and compiled in more than 500 reports. This report summarizes the major findings and accomplishments that have resulted from data-collection activities, hydrologic studies, and research concerned with the effects of coal mining on water resources. This summary report includes: (1) A description of the Nation's coal and water-resource issues related to coal development, including history, objectives, and design of the coal-hydrology program; (2) a summary of the hydrologic information collected in the major coal provinces and published in more than 500 reports and journal articles; and (3) a summary and application of results obtained from topical studies undertaken throughout the program, including discussions on watershed modeling, salinity modeling, ground-water flow systems, geochemistry of mine spoils, mine drainage, sedimentation, and aquatic biology. A detailed coal-hydrology reference list concludes the report.

continental United States↗

USGS2004

Preliminary integrated geologic map databases for the United States: Minnesota, Wisconsin, Michigan, Illinois, and Indiana

The growth in the use of Geographic Information Systems (GIS) has highlighted the need for regional and national digital geologic maps attributed with age and lithology information. Such maps can be conveniently used to generate derivative maps for purposes including mineral-resource assessment, metallogenic studies, tectonic studies, and environmental research. This Open-File Report is a preliminary version of part of a series of integrated state geologic map databases that cover the entire United States. The only national-scale digital geologic maps that portray most or all of the United States for the conterminous U.S. are the digital version of the King and Beikman (1974a, b) map at a scale of 1:2,500,000, as digitized by Schruben and others (1994) and the generalized digital version (Reed and Bush, 2004) of the Geologic Map of North America (Reed and others, 2005a, b) compiled at a scale of 1:5,000,000. The present series of maps is intended to provide the next step in increased detail. State geologic maps that range in scale from 1:100,000 to 1:1,000,000 are available for most of the country, and digital versions of these state maps are the basis for this product. In a few cases, new digital compilations were prepared (e.g. Ohio, South Carolina, South Dakota) or existing paper maps were digitized (e.g. Kentucky, Texas). Also as part of this series, new regional maps for Alaska and Hawaii are being compiled and ultimately new state maps will be produced. The digital geologic maps are presented in standardized formats as ARC/INFO export (.e00) files and as ArcView shape (.shp) files. Accompanying these spatial databases are a set of five supplemental attribute tables that relate the map units to detailed lithologic and age information. The maps for the CONUS have been fitted to a common set of state boundaries based on the 1:100,000 topographic map series of the United States Geological Survey (USGS). When the individual state maps are merged, the combined attribute tables can be used directly with the merged maps to make derivative maps. No attempt has been made to reconcile differences in mapped geology across state lines.

Illinois, Indiana, Michigan, Minnesota, Wisconsin↗

USGS2005

Preliminary integrated geologic map databases for the United States: Kentucky, Ohio, Tennessee, and West Virginia

The growth in the use of Geographic Information Systems (GIS) has highlighted the need for regional and national digital geologic maps attributed with age and lithology information. Such maps can be conveniently used to generate derivative maps for purposes including mineral-resource assessment, metallogenic studies, tectonic studies, and environmental research. This Open-File Report is a preliminary version of part of a series of integrated state geologic map databases that cover the entire United States. The only national-scale digital geologic maps that portray most or all of the United States for the conterminous U.S. are the digital version of the King and Beikman (1974a, b) map at a scale of 1:2,500,000, as digitized by Schruben and others (1994) and the generalized digital version (Reed and Bush, 2004) of the Geologic Map of North America (Reed and others, 2005a, b) compiled at a scale of 1:5,000,000. The present series of maps is intended to provide the next step in increased detail. State geologic maps that range in scale from 1:100,000 to 1:1,000,000 are available for most of the country, and digital versions of these state maps are the basis for this product. In a few cases, new digital compilations were prepared (e.g. Ohio, South Carloina, South Dakota) or existing paper maps were digitized (e.g. Kentucky, Texas). Also as part of this series, new regional maps for Alaska and Hawaii are being compiled and ultimately new state maps will be produced. The digital geologic maps are presented in standardized formats as ARC/INFO export (.e00) files and as ArcView shape (.shp) files. Accompanying these spatial databases are a set of five supplemental attribute tables that relate the map units to detailed lithologic and age information. The maps for the CONUS have been fitted to a common set of state boundaries based on the 1:100,000 topographic map series of the United States Geological Survey (USGS). When the individual state maps are merged, the combined attribute tables can be used directly with the merged maps to make derivative maps. No attempt has been made to reconcile differences in mapped geology across state lines.

Kentucky, Ohio, Tennessee, West Virginia↗

USGS2005

Preliminary integrated geologic map databases for the United States: Delaware, Maryland, New York, Pennsylvania, and Virginia

The growth in the use of Geographic Information Systems (GIS) has highlighted the need for regional and national digital geologic maps attributed with age and lithology information. Such maps can be conveniently used to generate derivative maps for purposes including mineral-resource assessment, metallogenic studies, tectonic studies, and environmental research. This Open-File Report is a preliminary version of part of a series of integrated state geologic map databases that cover the entire United States. The only national-scale digital geologic maps that portray most or all of the United States for the conterminous U.S. are the digital version of the King and Beikman (1974a, b) map at a scale of 1:2,500,000, as digitized by Schruben and others (1994) and the generalized digital version (Reed and Bush, 2004) of the Geologic Map of North America (Reed and others, 2005a, b) compiled at a scale of 1:5,000,000. The present series of maps is intended to provide the next step in increased detail. State geologic maps that range in scale from 1:100,000 to 1:1,000,000 are available for most of the country, and digital versions of these state maps are the basis for this product. In a few cases, new digital compilations were prepared (e.g. Ohio, South Carloina, South Dakota) or existing paper maps were digitized (e.g. Kentucky, Texas). Also as part of this series, new regional maps for Alaska and Hawaii are being compiled and ultimately new state maps will be produced. The digital geologic maps are presented in standardized formats as ARC/INFO export (.e00) files and as ArcView shape (.shp) files. Accompanying these spatial databases are a set of five supplemental attribute tables that relate the map units to detailed lithologic and age information. The maps for the CONUS have been fitted to a common set of state boundaries based on the 1:100,000 topographic map series of the United States Geological Survey (USGS). When the individual state maps are merged, the combined attribute tables can be used directly with the merged maps to make derivative maps. No attempt has been made to reconcile differences in mapped geology across state lines.

Delaware, Maryland, New York, Pennsylvania, Virgin↗

USGS1996

Earthquake prediction: The interaction of public policy and science

Earthquake prediction research has searched for both informational phenomena, those that provide information about earthquake hazards useful to the public, and causal phenomena, causally related to the physical processes governing failure on a fault, to improve our understanding of those processes. Neither informational nor causal phenomena are a subset of the other. I propose a classification of potential earthquake predictors of informational, causal, and predictive phenomena, where predictors are causal phenomena that provide more accurate assessments of the earthquake hazard than can be gotten from assuming a random distribution. Achieving higher, more accurate probabilities than a random distribution requires much more information about the precursor than just that it is causally related to the earthquake.

Conference Paper↗

USGS1964

Discharge characteristics of embankment-shaped weirs

An embankment-shaped weir is an embankment overtopped by flood waters. Among the engineering problems frequently resulting from. this occurrence is the need to compute the peak discharge from postflood yield observations. The research described in this. report was concerned with the theoretical and experimental bases for the computation procedure. The research had two main objectives. One was to determine the relationship between embankment form and roughness and some of the more important discharge characteristics. The second was to define, theoretically and experimentally, the relationship between free-flow discharge and the boundary layer on the roadway. The first objective was accomplished with the experimental determination of coefficients of discharge and other significant flow characteristics for a variety of boundary and flow conditions. The second objective was accomplished with the development and experimental verification of a discharge equation which involved the boundary layer displacement thickness. This phase of the research included a general investigation of boundary layer growth on the roadway. It is included that both free- and submerged-flow discharge are virtually independent of the influence of embankment shape and relative height. The influence of boundary resistance is appreciable only for smaller heads. The most practical solution for discharge is one which is based on. the simple weir equation and experimentally determined coefficients. A completely analytical equation of discharge is impractical. The report contains the results of 936 experiments on the discharge characteristics of 17 different models; plus 106 boundary-layer velocity traverses on 4 different models. The data are summarized in both graphical and tabular form.

Water Supply Paper↗

USGS2022

Nuclear magnetic resonance logging of a deep test well for estimation of aquifer and confining-unit hydraulic properties, Long Island, New York

A 1,200-foot deep well in southwestern Nassau County, Long Island, N.Y. was selected to evaluate the application of a nuclear magnetic resonance (NMR) logging tool. Technological advances in NMR borehole systems have allowed for reduced probe length and diameter, and focused measurement at specific diameters beyond the disturbed zone surrounding a well. This 3-inch-diameter NMR tool was specifically developed for use in deep 4-inch-diameter polyvinyl chloride cased wells common to Long Island. Selected intervals of the Magothy and Lloyd aquifers and the Raritan confining unit were logged for the evaluation. Unlike other petrophysical logs that respond to the rock matrix and fluid properties and are strongly dependent on mineralogy, NMR logs respond to the presence of hydrogen protons in the formation fluid to determine water fraction and pore-size distribution. NMR log analysis provided estimates of the clay-bound, capillary-bound, and mobile water fraction and hydraulic conductivity of aquifers and confining units penetrated by the well. NMR-estimated porosity and mobile water fraction for the Magothy aquifer (0.34 and 0.22 respectively), Magothy/Raritan(?) (0.35 and 0.30), Raritan confining unit (0.30 and 0.13), Raritan clay and silt (0.23 and 0.01), and the Lloyd aquifer (0.27 and 0.19) was determined from the NMR log. Hydraulic conductivity was estimated from the NMR-log data using the Schlumberger- Doll Research and sum of squared echoes equations with empirically derived constants for unconsolidated aquifers. Average hydraulic conductivity of the Magothy aquifer was 70 ft/d, the Raritan confining unit was 9.0 ft/d overall, the clay-rich lower part 0.24 ft/d, and the Lloyd aquifer was 56 ft/d. The coarse sandy Magothy/Raritan(?) unit between the Magothy aquifer and the top of the Raritan confining unit had the highest hydraulic conductivity of 345 ft/d. The hydraulic-conductivity estimates from the NMR log analysis for the Magothy and Lloyd aquifers were consistent with published values and that estimated for the Lloyd aquifer from a specific-capacity test at the well site.

New York↗

USGS2011

Quantifying the fire regime distributions for severity in Yosemite National Park, California, USA

This paper quantifies current fire severity distributions for 19 different fire-regime types in Yosemite National Park, California, USA. Landsat Thematic Mapper remote sensing data are used to map burn severity for 99 fires (cumulatively over 97 000 ha) that burned in Yosemite over a 20-year period. These maps are used to quantify the frequency distributions of fire severity by fire-regime type. A classification is created for the resultant distributions and they are discussed within the context of four vegetation zones: the foothill shrub and woodland zone; the lower montane forest zone; the upper montane forest zone and the subalpine forest zone. The severity distributions can form a building block from which to discuss current fire regimes across the Sierra Nevada in California. This work establishes a framework for comparing the effects of current fires on our landscapes with our notions of how fires historically burned, and how current fire severity distributions differ from our desired future conditions. As this process is refined, a new set of information will be available to researchers and land managers to help understand how fire regimes have changed from the past and how we might attempt to manage them in the future.

California↗

USGS2026

Origins, evolutions, and future directions of Landsat science products for advancing global inland water and coastal ocean observations

In April 2020, the U.S. Geological Survey (USGS) Earth Resources Observation and Science (EROS) Center introduced a Level 2 provisional Aquatic Reflectance (AR) product for the Landsat 8 Operational Land Imager (OLI), marking the initial phase in developing a standardized global product for Landsat-derived surface water measurements. The goal of USGS EROS aquatic product research and development is to prepare for an operational processing architecture for Landsat Collection 3 in the late 2020s that will enable use of quality-controlled data for emerging Landsat aquatic science applications. To achieve this, we released a subset of the Landsat 8/9 provisional AR products (Crawford et al., 2025, https://doi.org/10.5066/P14MBBRM) and examined its general performance through the Science Algorithms to Operations (SATO) framework alongside quantitative assessment using community made inland water data records (GLObal Reflectance community dataset for Imaging and optical sensing of Aquatic environments, GLORIA) and radiometric coastal validation platforms (NASA’s Ocean Color component of the Aerosol Robotic Network, AERONET-OC). Variability within the validation datasets indicate that the performance of the Landsat 8/9 provisional AR retrieval is highly context-dependent; errors are minimal in optically simple waters (e.g., clear to moderately turbid coastal waters) but increase considerably in optically complex waters where factors such as elevated levels of turbidity, chlorophyll (Chl a ) concentrations, or colored dissolved organic matter (CDOM) dominate the water column. Additionally, this paper examines key algorithmic considerations for atmospheric correction, highlighting factors that influence accuracy, scalability, and computational efficiency necessary for collection processing in the operational Landsat Product Generation System (LPGS). This paper is intended to communicate with aquatic scientists, satellite oceanographers, and the broader Earth observation community on the origins, requirements, challenges, successes, and future objectives for operationalizing global AR data products for Landsat satellite missions.

Earth System Science Data↗

USGS1971

EROS — New observation vantage points and processes

The EROS Program objective is to utilize aircraft and spacecraft remote-sensing technology as complementary parts of integrated data collection, processing, and dissemination systems to support resources research and management functions of the Department of the Interior. The Program develops and coordinates research in the applications of new sensors for resources applications in cooperation with NASA. At present there are two major areas of activity: present there are two major areas of activity: The first is related to the Earth Resources Technology Satellite (ERTS). The second is a suite of projects designed to determine the applicability of new aerial and satellite sensing systems and techniques to geologic, geographic, hydrologic, and topographic mapping and for supporting natural resources management functions of the Department of the Interior. Programs with similar goals for agriculture and forestry, and for oceanography are being conducted in the Departments of Agriculture, Commerce, the Naval Oceanographic Office, and in a number of colleges and universities. The first satellite designed specifically for resources research and applications, ERTS-A, is to be launched in early 1972. It will be an unmanned satellite carrying three experimental systems: A three camera Return Beam Vidicon (RBV) system, a 4-band Multispectral Scanning (MSS) radiometer system, and a Data Collection System (DCS). The RBV cameras will photograph simultaneously and instantaneously areas of the earth 100 × 100 nautical miles - or 10,000 square nautical miles - in the blue-green (.475-.575mu m), the red (.580-.680mu m), and the near infrared (.690-.830mu m). The MSS will record three wavelength bands in the same general spectral range and the fourth band (8.0 mu m) will extend farther into the infrared...

Conference Paper↗

USGS1915

Analyses of rocks and minerals from the laboratory of the United States Geological Survey, 1880 to 1914

The present Geological Survey of the United States was organized in 1879. In 1880, in connection with the Colorado work, a chemical laboratory was established at Denver in charge of W. F. Hillebrand, with whom were associated Antony Guyard and, later, L. G. Eakins. In 1882 W. H. Melville was placed in charge of a second laboratory at San Francisco, and in the autumn of 1883 the central laboratory was started in Washington, with myself as chief chemist. In November, 1885, Dr. Hillebrand was transferred to Washington; early in 1888 he was followed by Mr. Eakins, and the Denver laboratory was discontinued. In the spring of 1890 Dr. Melville also was transferred to Washington, and since then the geochemical work of the Survey has been concentrated at headquarters. The special laboratories of the water-resources and technologic branches of the Survey are not included in this statement and their work is not represented in this bulletin. Up to January 1, 1914, nearly 8,000 analyses have been made in the laboratory at Washington of rocks, minerals, ores, waters, sediments, coals, metals, and other substances with which geology has to do. Some-hundreds of analyses were also made in the laboratories at Denver and San Francisco. A fair amount of research work upon mineralogical and analytical problems has also been done. In *all of this work the following chemists have been employed: E. T. Allen, R. K. Bailey, Charles Catlett, T. M. Chatard, F. W. Clarke, L. G. Eakins, J. G. Fairchild, F. A. Gooch, Antony Guyard, W. B. Hicks, W. F. Hillebrand, W. F. Hunt, W. H. Melville, H. C. McNeil, Chase Palmer, R. B. Riggs, W. T. Schaller, E. A. Schneider, George Steiger, H. N. Stokes, E. C. Sullivan, William Valentine, R. C. Wells, W. C. Wheeler, and J. E. Whitfield. At present, January 1, 1914, eight of these chemists are employed in the Survey. Other officers of the Survey have been occupied more or less with chemical questions, but the men named in this list were connected directly with the laboratory. Some work for the chemical division has also been done by chemists not regularly on the rolls of the Survey, but their analyses, with the exception of a single group to be noted later, do not fall within the scope of this paper.

Bulletin↗

USGS2005

Preliminary integrated geologic map databases for the United States: Alabama, Florida, Georgia, Mississippi, North Carolina, and South Carolina

The growth in the use of Geographic Information Systems (GIS) has highlighted the need for regional and national digital geologic maps attributed with age and lithology information. Such maps can be conveniently used to generate derivative maps for purposes including mineral-resource assessment, metallogenic studies, tectonic studies, and environmental research. This Open-File Report is a preliminary version of part of a series of integrated state geologic map databases that cover the entire United States. The only national-scale digital geologic maps that portray most or all of the United States for the conterminous U.S. are the digital version of the King and Beikman (1974a, b) map at a scale of 1:2,500,000, as digitized by Schruben and others (1994) and the digital version of the Geologic Map of North America (Reed and others, 2005a, b) compiled at a scale of 1:5,000,000 which is currently being prepared by the U.S. Geological Survey. The present series of maps is intended to provide the next step in increased detail. State geologic maps that range in scale from 1:100,000 to 1:1,000,000 are available for most of the country, and digital versions of these state maps are the basis of this product. In a few cases, new digital compilations were prepared (e.g. OH, SC, SD) or existing paper maps were digitized (e.g. KY, TX). For Alaska and Hawaii, new regional maps are being compiled and ultimately new state maps will be produced. The digital geologic maps are presented in standardized formats as ARC/INFO (.e00) export files and as ArcView shape (.shp) files. Accompanying these spatial databases are a set of five supplemental data tables that relate the map units to detailed lithologic and age information. The maps for the CONUS have been fitted to a common set of state boundaries based on the 1:100,000 topographic map series of the United States Geological Survey (USGS). When the individual state maps are merged, the combined attribute tables can be used directly with the merged maps to make derivative maps. No attempt has been made to reconcile differences in mapped geology across state lines.

Alabama, Florida, Georgia, Mississippi, North Caro↗

USGS2005

Preliminary integrated geologic map databases for the United States: Central states: Montana, Wyoming, Colorado, New Mexico, North Dakota, South Dakota, Nebraska, Kansas, Oklahoma, Texas, Iowa, Missouri, Arkansas, and Louisiana

The growth in the use of Geographic Information Systems (GIS) has highlighted the need for regional and national digital geologic maps attributed with age and lithology information. Such maps can be conveniently used to generate derivative maps for purposes including mineral-resource assessment, metallogenic studies, tectonic studies, and environmental research. This Open-File Report is a preliminary version of part of a series of integrated state geologic map databases that cover the entire United States. The only national-scale digital geologic maps that portray most or all of the United States for the conterminous U.S. are the digital version of the King and Beikman (1974a, b) map at a scale of 1:2,500,000, as digitized by Schruben and others (1994) and the digital version of the Geologic Map of North America (Reed and others, 2005a, b) compiled at a scale of 1:5,000,000 which is currently being prepared by the U.S. Geological Survey. The present series of maps is intended to provide the next step in increased detail. State geologic maps that range in scale from 1:100,000 to 1:1,000,000 are available for most of the country, and digital versions of these state maps are the basis of this product. In a few cases, new digital compilations were prepared (e.g. OH, SC, SD) or existing paper maps were digitized (e.g. KY, TX). For Alaska and Hawaii, new regional maps are being compiled and ultimately new state maps will be produced. The digital geologic maps are presented in standardized formats as ARC/INFO (.e00) export files and as ArcView shape (.shp) files. Accompanying these spatial databases are a set of five supplemental data tables that relate the map units to detailed lithologic and age information. The maps for the CONUS have been fitted to a common set of state boundaries based on the 1:100,000 topographic map series of the United States Geological Survey (USGS). When the individual state maps are merged, the combined attribute tables can be used directly with the merged maps to make derivative maps. No attempt has been made to reconcile differences in mapped geology across state lines. This is the first version of this product and it will be subsequently updated to include four additional states (North Dakota, South Dakota, Nebraska, and Iowa)

Arkansas, Colorado, Iowa, Kansas, Louisiana, Misso↗

USGS1995

Preliminary Geologic Map of the Topanga 7.5' Quadrangle, Southern California: A Digital Database

INTRODUCTION This Open-File report is a digital geologic map database. This pamphlet serves to introduce and describe the digital data. There is no paper map included in the Open-File report. This digital map database is compiled from previously published sources combined with some new mapping and modifications in nomenclature. The geologic map database delineates map units that are identified by general age and lithology following the stratigraphic nomenclature of the U. S. Geological Survey. For detailed descriptions of the units, their stratigraphic relations and sources of geologic mapping consult Yerkes and Campbell (1994). More specific information about the units may be available in the original sources. The content and character of the database and methods of obtaining it are described herein. The geologic map database itself, consisting of three ARC coverages and one base layer, can be obtained over the Internet or by magnetic tape copy as described below. The processes of extracting the geologic map database from the tar file, and importing the ARC export coverages (procedure described herein), will result in the creation of an ARC workspace (directory) called 'topnga.' The database was compiled using ARC/INFO version 7.0.3, a commercial Geographic Information System (Environmental Systems Research Institute, Redlands, California), with version 3.0 of the menu interface ALACARTE (Fitzgibbon and Wentworth, 1991, Fitzgibbon, 1991, Wentworth and Fitzgibbon, 1991). It is stored in uncompressed ARC export format (ARC/INFO version 7.x) in a compressed UNIX tar (tape archive) file. The tar file was compressed with gzip, and may be uncompressed with gzip, which is available free of charge via the Internet from the gzip Home Page (http://w3.teaser.fr/~jlgailly/gzip). A tar utility is required to extract the database from the tar file. This utility is included in most UNIX systems, and can be obtained free of charge via the Internet from Internet Literacy's Common Internet File Formats Webpage http://www.matisse.net/files/formats.html). ARC/INFO export files (files with the .e00 extension) can be converted into ARC/INFO coverages in ARC/INFO (see below) and can be read by some other Geographic Information Systems, such as MapInfo via ArcLink and ESRI's ArcView (version 1.0 for Windows 3.1 to 3.11 is available for free from ESRI's web site: http://www.esri.com). 1. Different base layer - The original digital database included separates clipped out of the Los Angeles 1:100,000 sheet. This release includes a vectorized scan of a scale-stable negative of the Topanga 7.5 minute quadrangle. 2. Map projection - The files in the original release were in polyconic projection. The projection used in this release is state plane, which allows for the tiling of adjacent quadrangles. 3. File compression - The files in the original release were compressed with UNIX compression. The files in this release are compressed with gzip.

Open-File Report↗