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USGS2026

Making many out of one: Synthetic geologic deformation model distributions for use in USGS NSHM25‐PRVI Puerto Rico-U.S. Virgin Island update

A key use‐case of geologic slip rates is within deformation models used in probabilistic seismic hazard analyses. Field‐derived geologic slip rates have formed the cornerstone of deformation models in such applications for decades. Recent advancements in seismic hazard analyses have expanded the use of faults for which geologic slip rates are not well constrained using categorical slip rate estimates. Because of these advancements, application of a geologic deformation model for use in 2025 U.S. Geological Survey National Seismic Hazard Model Puerto Rico‐U.S. Virgin Islands (NSHM25‐PRVI) proved challenging due to: (1) a lack of field‐based geologic slip rates, and (2) a lack of epistemic uncertainty distributions within a broad range of estimated slip rates. Preliminary versions of the NSHM25‐PRVI model sampled these slip rate bins in a coincident manner along preferred and extreme value branches, which yielded untenable correlations in mean hazard results. To minimize the influence of correlated uncertainties amid these challenges, we develop a synthetic epistemic uncertainty distribution for deformation rate on each crustal fault. Each fault has a weighting schema across four possible distribution shapes: uniform, normal, triangular favoring local minima, and triangular favoring local maxima. The synthetic distributions are then sampled several times for each logic tree branch. The results provide a more realistic distribution of rates across the study region as compared with using correlated extrema sampling. This exploration of our method in a small region like PRVI can pave the way for larger‐scale, more complicated applications (e.g., western United States).

Puerto Rico, US Virgin Islands↗

USGS2012

Geologic processes influence the effects of mining on aquatic ecosystems

Geologic processes strongly influence water and sediment quality in aquatic ecosystems but rarely are geologic principles incorporated into routine biomonitoring studies. We test if elevated concentrations of metals in water and sediment are restricted to streams downstream of mines or areas that may discharge mine wastes. We surveyed 198 catchments classified as “historically mined” or “unmined,” and based on mineral-deposit criteria, to determine whether water and sediment quality were influenced by naturally occurring mineralized rock, by historical mining, or by a combination of both. By accounting for different geologic sources of metals to the environment, we were able to distinguish aquatic ecosystems limited by metals derived from natural processes from those due to mining. Elevated concentrations of metals in water and sediment were not restricted to mined catchments; depauperate aquatic communities were found in unmined catchments. The type and intensity of hydrothermal alteration and the mineral deposit type were important determinants of water and sediment quality as well as the aquatic community in both mined and unmined catchments. This study distinguished the effects of different rock types and geologic sources of metals on ecosystems by incorporating basic geologic processes into reference and baseline site selection, resulting in a refined assessment. Our results indicate that biomonitoring studies should account for natural sources of metals in some geologic environments as contributors to the effect of mines on aquatic ecosystems, recognizing that in mining-impacted drainages there may have been high pre-mining background metal concentrations.

Ecological Applications↗

USGS2019

Discovering blind geothermal systems in the Great Basin Region: An integrated geologic and geophysical approach for establishing geothermal play fairways: All phases

Most geothermal resources in the Great Basin region of the western USA are blind, and thus the discovery of new commercial-grade systems requires synthesis of favorable characteristics for geothermal activity. The geothermal play fairway concept involves integration of multiple parameters indicative of geothermal activity to identify promising areas for new development. This project integrated multiple datasets to apply the play fairway concept and assess geothermal potential in a large region of the Great Basin in Nevada. It is therefore referred to as the Nevada play fairway project. This project was a strong collaborative effort between several organizations, led by the Nevada Bureau of Mines and Geology at the University of Nevada, Reno, but with key support from the U.S. Geological Survey, ATLAS Geosciences, Inc,, Hi-Q Geophysical, Inc., Lawrence Berkeley National Laboratory, Utah Geological Survey, and Innovative Geothermal Ltd. In Budget Period 1 of this project, available data for nine geologic, geochemical, and geophysical parameters were initially synthesized to produce a new detailed geothermal potential map of 96,000 km2 from west-central to eastern Nevada (Figure 1). These parameters were grouped into subsets and individually weighted (Figure 2) to delineate rankings for local permeability, intermediate permeability, regional permeability, and thermal potential, which collectively defined geothermal play fairways (i.e., most likely locations for significant geothermal fluid flow). This initial work was aimed at reducing the risks in regional exploration and therefore facilitating discovery of new commercial-grade systems in blind settings, as well as in areas with surface expressions of geothermal activity. Budget Period 2 of the project involved detailed analysis of some of the most promising areas identified in Phase 1. Twenty-four highly prospective areas, including both known undeveloped systems and previously undiscovered potential blind systems, were identified for further analysis (Figures 3 and 4). After reconnaissance of these areas, five of the most promising sites were selected for detailed studies. Multiple techniques were employed in the detailed studies, including geologic mapping, shallow temperature surveys, gravity surveys, Lidar, geochemical studies, seismic reflection analysis, and 3D modeling. The goal of the detailed studies was to identify specific areas with the highest likelihood for high permeability and thermal fluids, such that drill sites could be targeted. Three main sets of predictive maps were generated for each detailed study area: 1) play fairway maps, 2) play fairway error maps, and 3) direct evidence maps. Local- and intermediate-scale permeability models were revised to reflect results of the detailed geologic, geophysical, and geochemical analyses. Budget Period 3 of the project involved more detailed geophysical analyses and temperature-gradient (TG) drilling in southeastern Gabbs Valley and northern Granite Springs Valley (Figure 4), deemed the two most promising sites, with the goal of providing preliminary validation of the play fairway methodology. In southeastern Gabbs Valley, the collocation of a favorable structural setting (displacement transfer zone and fault intersections), Quaternary faults, intersecting and terminating gravity gradients, magnetic low, shallow (2 m) temperature anomaly, low resistivity anomaly, and promising geothermometry from nearby water wells provided evidence for a blind system. Drilling of six TG holes defines an apparent geothermal system at this locality with temperatures as high as 124°C at 152 m. This system is blind, with no surface hot springs, fumaroles, or paleo-geothermal deposits. For northern Granite Springs Valley, a favorable structural setting (termination of a major Quaternary normal fault), terminating gravity gradient, magnetic gradient, newly discovered sinter deposits, nearby warm water wells, previously drilled TG holes in the vicinity, and promising geothermometry suggest a hidden system. Drilling of six new TG holes yields temperatures of ~96°C at ~250 m, suggesting the presence of a geothermal system. Major lessons learned in the course of this project include: 1) initially identified sites commonly include multiple favorable structural settings at a finer scale; 2) promising sites in Cenozoic basins cannot be recognized without detailed geophysical surveys; and 3) play fairway analysis should be refined as the exploration program vectors into the most promising sites and finer-scale data are acquired. In addition to producing copious amounts of data, this project resulted in 16 published papers, 10 abstracts, more than 40 presentations across the U.S. and abroad (including several keynote addresses), 2 Masters theses, and 7 media reports.

Nevada↗

USGS2000

Superfund GIS - 1:250,000 Geology of Tennessee

This data set is a digital representation of the printed 1:250,000 geologic maps from the Tennessee Department of Environment and Conservation, Division of Geology. The coverage was designed primarily to provide a more detailed geologic base than the 1:2,500,000 King and Beikman (1974). 1:24,000 scale coverage of the state is available for about 40 percent of the state. Formation names and geologic unit codes used in the coverage are from the Tennessee Division of Geology published maps and may not conform to USGS nomenclature. The Tennessee Division of Geology can be contacted at (615) 532-1500

Tennessee↗

USGS1969

Surficial Geology of Mount Rainier National Park, Washington

Much of the ground surface around Mount Rainier volcano is directly underlain by loose geologic deposits that veneer the hard rock formations. Examples of these deposits are sand and gravel bars along the rivers, ridges of loose rock debris beside the glaciers, and sloping aprons of rock fragments beneath almost every cliff. Even though they are generally thin and inconspicuous when compared with the rock formations, these surficial deposits are clues to geologic events that have profoundly influenced the shape of the park's landscape. Thus, from the character and extent of glacial deposits one can judge the age and size of former glaciers that carved the cirques and deep canyons of the park; from the mudflows which streamed down nearly every valley one can infer the age and size of huge landslides of the past that helped determine Mount Rainier's present shape; and from the pumice deposits some of the volcano's recent eruptive activity can be reconstructed. The map (plate 1, in pocket) that accompanies this description of the surficial deposits of Mount Rainier National Park shows the location of the various geologic formations, and the explanation shows the formations arranged in order of their relative age, with the oldest at the bottom. The text describes the surficial deposits in sequence from older to younger. A discussion of the pumice deposits of the park, which were not mapped, is followed by a description of the formations shown on the geologic map. Inspection of the geologic map may lead the viewer to question why the surficial deposits are shown in more detail in a zone several miles wide around the base of the volcano than elsewhere. This is partly because the zone is largely near or above timberline, relatively accessible, and the surficial deposits there can be readily recognized, differentiated, and mapped. In contrast, access is more difficult in the heavily timbered parts of the park, and surficial deposits there are generally blanketed by a dense virgin forest and are rarely exposed. Geologic investigations in such areas of the park were of a reconnaissance nature.

Bulletin↗

USGS1929

Geology of the De Queen and Caddo Gap quadrangles, Arkansas

The field study of the geology of the De Queen and Caddo Gap quadrangles extended over a period of many years, and although the scientific and economic results from the study are here set forth fully for the first time in a single report, a number of publications have been issued that have presented some of the more important results. The field work was begun in 1907 and continued intermittently until 1925. The work in 1907 was done under a cooperative agreement between the United States Geological Survey and the Arkansas Geological Survey and involved primarily an investigation of the slate deposits of west-central Arkansas but also the mapping of the rocks in the mountainous part of the Caddo Gap quadrangle. In that year A. H. Purdue, State geologist of Arkansas, had charge of the work and was assisted by R. D. Mesler and H. D. Miser. All the subsequent work in the Caddo Gap quadrangle, as well as all in the De Queen quadrangle, was done by the United States Geological Survey. The work since 1907 is briefly outlined below. In 1908 Mr. Purdue, assisted by Mr. Miser, completed the mapping of the rocks of the Caddo Gap quadrangle with the aid of valuable suggestions from C. W. Hayes, chief geologist, J. A. Taff, and E. O. Ulrich, who visited the field for several days. In 1910 Mr. Purdue, assisted by Mr. Miser, reviewed a part of the previous work in the Caddo Gap quadrangle and mapped the rocks in most of the mountainous portion of the De Queen quadrangle. In 1911 these geologists did additional work in both the De Queen and Caddo Gap quadrangles, and in 1912 Mr. Miser, assisted by Mr. Mesler, completed the mapping of the rocks in the De Queen quadrangle and then reviewed some of the earlier work in the Caddo Gap quadrangle. In 1913 Arthur Keith, and Messrs. Purdue and Miser spent several days in a field conference in the Caddo Gap quadrangle. During the conference the first identifiable fossils in the Blaylock sandstone, of Silurian age, were discovered. In 1914 Mr. Miser obtained a small collection of fossil plants from the Stanley shale near Gillham, Ark., also the first fossils from the Arkansas novaculite. In 1916 he made a special study of some of the mineral deposits of the quadrangles, including the deposits of diamonds, manganese ore, gravel, and asphalt, and in 1917 he revisited the diamond mines. An investigation of the volcanic ash and tuff in the "Bingen formation," of Upper Cretaceous age, in the Caddo Gap quadrangle and adjoining areas to the south and southwest was made in 1923 by Clarence S. Ross and Mr. Miser. Also in that year other fossil plants were collected from the Stanley shale at the earlier discovered locality near Gillham by Mr. Miser. (See pl. 9, A .) The aggregate time spent in collecting fossils at this locality was eight days, so scare are the fossils and so difficult are the conditions for collecting them. Besides the above work the authors made frequent reconnaissance studies of adjoining areas, and Mr. Miser was joined in 1923 by C. W. Honess for a field conference of a few days in the De Queen and Caddo Gap quadrangles. In 1925 Mr. Miser joined in the field Messrs. L. W. Stephenson and C. H. Dane for a few days in a study of the " Bingen " (Woodbine and Tokio) and other formations of Upper Cretaceous age in and near the Caddo Gap quadrangle. Mr. Dane was making at that time a special study of the deposits of Upper Cretaceous age in southwestern Arkansas under a cooperative agreement between the United States Geological Survey and the Arkansas Geological Survey. For some of the information on the Tokio formation the present writers are indebted to Mr. Dane.

Arkansas, Oklahoma↗

USGS2007

About the geologic map in the National Atlas of the United States of America

Introduction The geologic map in the National Atlas of the United States of America shows the age, distribution, and general character of the rocks that underlie the Nation, including Alaska, Hawaii, Puerto Rico, and the Virgin Islands (but excluding other small island possessions). (The National Atlas of the United States can be accessed at URL http://nationalatlas.gov/natlas/Natlasstart.asp.) The map depicts the bedrock that lies immediately beneath soils or surficial deposits except where these deposits are so thick and extensive that the type of bedrock beneath them can only be inferred by deep drilling or geophysical methods, or both. Thus, it does not show the extensive glacial deposits of the North Central and Northeastern States, the deep residuum of the Southeastern and South Central States, the relatively thin alluvium along many major rivers and basins, and extensive eolian deposits on the high plains. However, it does show, in a general way, the thick alluvial deposits along the lower Mississippi River and on the Atlantic and Gulf Coastal Plains, and in the deep basins of the western cordillera. The rocks are classified as either sedimentary, volcanic, plutonic, or metamorphic, and their geologic ages are given in terms using a simplified version of the 1999 Geological Society of America geologic time scale. In some places rocks depicted as sedimentary are interlayered with volcanic rocks, including tuff, volcanic breccia, and volcanic flows. Conversely, many of the rocks shown as volcanic include interlayered sedimentary rocks. Plutonic rocks are classified by age and as granitic, intermediate, mafic, or ultramafic, but no similar classification has been attempted for the volcanic rocks in this version of the map. Where sedimentary or volcanic rocks have been metamorphosed but still retain clear evidence of their depositional age and origin, the extent of the metamorphism is shown by a pattern. Where the metamorphism has been so intense that the rocks bear little resemblance to the rocks from which they were derived, they are mapped as gneiss, but the age given is generally the age of the original rocks. The map in the National Atlas is a generalization of a new geologic map of North America that has recently been published by the Geological Society of America. The original compilation was prepared at a scale of 1:2,500,000 for publication at a scale of 1:5,000,000. This generalized version is intended for viewing at scales between about 1:10,000,000 and 1:7,500,000.

Circular↗

USGS2010

Protocols for geologic hazards response by the Yellowstone Volcano Observatory to activity within the Yellowstone Volcanic System

Executive Summary The Yellowstone Plateau hosts an active volcanic system, with subterranean magma (molten rock), boiling, pressurized waters, and a variety of active faults with significant earthquake hazards. Within the next few decades, light-to-moderate earthquakes and steam explosions are certain to occur. Volcanic eruptions are less likely, but are ultimately inevitable in this active volcanic region. This document summarizes protocols, policies, and tools to be used by the Yellowstone Volcano Observatory (YVO) during earthquakes, hydrothermal explosions, or any geologic activity that could lead to a volcanic eruption. Yellowstone National Park is home to Yellowstone Caldera, the largest volcanic system by volume in the United States, as well as a vigorous hydrothermal system composed of pressurized subsurface boiling waters and active faults capable of generating substantial seismicity. The region is subject to hazards spanning a wide range of intensities, magnitudes, likelihood of occurrence, and geographic extent of impact. These hazards include small and comparatively common hydrothermal explosions, occasional strong earthquakes, rare relatively non-explosive lava flows, and very rare large explosive volcanic eruptions. Addressing the broad style of potential hazards and the vast spatial and temporal scales over which these hazards can occur requires a general plan that outlines the Yellowstone Volcano Observatory (YVO) response to a hazardous or potentially hazardous geological event or unrest (defined as departure from normal activity levels). The U.S. Geological Survey (USGS) Volcano Science Center (VSC) Response Plan for Significant Volcanic Events in the United States (Moran and others, 2024) forms the basis of any response by YVO but will be modified to suit the specific characteristics of the observatory, which operates as a consortium of nine federal, state, and academic institutions. Decisions on declaring an event response or “activity with potential” (defined as unrest that is not immediately hazardous but that may evolve into a hazardous event), as well as any changes in Volcano Alert Level and Aviation Color Code or the release of formal Information Statements, will be made by the USGS via the YVO Scientist-in-Charge (SIC) in consultation with the leads of the YVO member agencies. The YVO response to hazardous or potentially hazardous geological activity in or around Yellowstone National Park will focus on the collection and analysis of data relevant to the location and style of the activity. Those data will be interpreted within the existing geological framework for the region to develop probabilistic assessments of potential outcomes. These interpretations and assessments will be used to support decision making by emergency management officials including Yellowstone National Park managers or within the National Incident Management System if an Incident Command System (ICS) is activated. YVO will also convene a communications group open to each member agency to ensure consistent internal and external messaging and that the public is kept informed of the unrest through formal notifications, social media posts, online content, traditional media interviews, and community meetings. This response plan will be evaluated and updated as needed by the observatory and will be available through the YVO and USGS public websites. Responses to volcanic eruptions and responses outside of the Yellowstone region, but within the YVO area of responsibility (including Arizona, Utah, New Mexico, and Colorado), will follow the U.S. Geological Survey Volcano Science Center Response Plan for Significant Volcanic Events in the United States (Moran and others, 2024).

Idaho, Montana, Wyoming↗

USGS1978

The United States Geological Survey in Alaska; organization and status of programs in 1978

United States Geological Survey projects in Alaska study a wide range of topics of economic and scientific interest. Work done in 1977 includes contributions to economic geology, regional geology, stratigraphy, engineering geology, hydrology, and marine geology. Many maps and reports covering various aspects of the geology and mineral and water resources of the State were published. In addition, the published 1:1,000,000-scale map of the State has been revised in two areas. A bibliography containing 263 reports on Alaska published in 1977 is included. (Woodard-USGS)

Circular↗

USGS1978

The United States Geological Survey in Alaska: Accomplishments during 1977

Alaska↗

USGS1984

Between Mount St. Helens and the world: How the U.S. Geological Survey provided news-media information on the 1980 volcanic eruptions

The eruptions of Mount St. Helens volcano, Wash., constituted one of the major national and international news stories of 1980 and involved the U.S. Geological Survey in more news coverage than any other event in its history. Much of the information about the volcano came from monitoring and research by geologists, geophysicists, hydrologists, and other scientists of the U.S. Geological Survey. This scientific information was distributed to the public, through news media, by U.S. Geological Survey personnel. Key members of this group were Mount St. Helens hazards assessment scientists, monitoring scientists, and research scientists; public affairs officers; and the Information Scientist for Mount St. Helens. The Information Scientist, a geologist or geophysicist, assumed the major role of on-site (Vancouver, Wash.) news spokesman about a week after the main eruption of May 18. The Geological Survey released information through news conferences, interviews, news pools of reporters and cameramen on trips to the volcano, special television and radio appearances, news releases, and informal contacts with reporters. Members of the U.S. Forest Service, Federal Emergency Management Agency, State of Washington, and other government agencies cooperated extensively with the Geological Survey. By providing assistance to news representatives, the Geological Survey and these other agencies helped effect rapid dissemination of the background information and daily events of a highly complex story while limiting disruption to the scientific working team and minimizing dangers to reporters and scientists.

Washington↗

USGS2008

Database of the geology and thermal activity of Norris Geyser Basin, Yellowstone National Park

This dataset contains contacts, geologic units and map boundaries from Plate 1 of USGS Professional Paper 1456, 'The Geology and Remarkable Thermal Activity of Norris Geyser Basin, Yellowstone National Park, Wyoming.' The features are contained in the Annotation, basins_poly, contours, geology_arc, geology_poly, point_features, and stream_arc feature classes as well as a table of geologic units and their descriptions. This dataset was constructed to produce a digital geologic map as a basis for studying hydrothermal processes in Norris Geyser Basin. The original map does not contain registration tic marks. To create the geodatabase, the original scanned map was georegistered to USGS aerial photographs of the Norris Junction quadrangle collected in 1994. Manmade objects, i.e. roads, parking lots, and the visitor center, along with stream junctions and other hydrographic features, were used for registration.

Data Series↗

USGS2008

Relational database for the geology of the northern Rocky Mountains— Idaho, Montana, and Washington

A relational database was created to prepare and organize geologic map-unit and lithologic descriptions for input into a spatial database for the geology of the northern Rocky Mountains, a compilation of forty-three geologic maps for parts of Idaho, Montana, and Washington in U.S. Geological Survey Open File Report 2005-1235. Not all of the information was transferred to and incorporated in the spatial database due to physical file limitations. This report releases that part of the relational database that was completed for that earlier product. In addition to descriptive geologic information for the northern Rocky Mountains region, the relational database contains a substantial bibliography of geologic literature for the area. The relational database nrgeo.mdb (linked below) is available in Microsoft Access version 2000, a proprietary database program. The relational database contains data tables and other tables used to define terms, relationships between the data tables, and hierarchical relationships in the data; forms used to enter data; and queries used to extract data.

Idaho, Montana, Washington↗

USGS2003

Petroleum systems and geologic assessment of oil and gas in the Uinta-Piceance Province, Utah and Colorado

The purpose of the U.S. Geological Survey's (USGS) National Oil and Gas Assessment is to develop geology-based hypotheses regarding the potential for additions to oil and gas reserves in priority areas of the United States, focusing on the distribution, quantity, and availability of oil and natural gas resources. The USGS has recently completed an assessment of the undiscovered oil and gas potential of the Uinta-Piceance Province of northeastern Utah and northwestern Colorado (USGS Province 5020). The Uinta- Piceance Province is a priority province for the National Assessment because of its potential for significant natural gas resources. The assessment of this province is based on geologic principles and uses the total petroleum system concept. The geologic elements of a total petroleum system include hydrocarbon source rocks (source rock maturation, hydrocarbon generation and migration), reservoir rocks (sequence stratigraphy, petrophysical properties), and hydrocarbon traps (trap formation and timing). In the Uinta-Piceance Province, the USGS used this geologic framework to define five total petroleum systems and 20 assessment units within the total petroleum systems, and quantitatively estimated the undiscovered oil and gas resources within each assessment unit. Many more details about the project and about individual chapters of this report are readily available in the very readable Chapter 2 of this volume, 'The Uinta-Piceance Province-Introduction to a geologic assessment of undiscovered oil and gas resources.' Use Acrobat Reader to access the PDF for this chapter.

Colorado, Utah↗

USGS2002

Surficial geologic maps along the riparian zone of the Animas River and its headwater tributaries, Silverton to Durango, Colorado, with upper Animas River watershed gradient profiles

This product consists of Adobe Acrobat .PDF format documents for 10 surficial geologic strip maps along the Animas River watershed from its major headwater tributaries, south to Durango, Colorado. The Animas River originates in the San Juan Mountains north of the historic mining town of Silverton, Colorado. The surficial geologic maps identify surficial deposits, such as flood-plain and terrace gravels, alluvial fans, glacial till, talus, colluvium, landslides, and bogs. Sixteen primary units were mapped that included human-related deposits and structures, eight alluvial, four colluvial, one glacial, travertine deposits, and undifferentiated bedrock. Each of the surficial geologic strip maps has .PDF links to surficial geology photographs, which enable the user to take a virtual tour of these deposits. Geochemical data collected from mapped surficial deposits that pre- and postdate mining activity have aided in determining the geochemical baseline in the watershed. Several photographs with their corresponding geochemical baseline profiles are accessible through .PDF links from several of the maps. A single coverage for all surficial deposits mapped is included as an ArcInfo shape file as an Arc Export format .e00 file. A gradient map for major headwater tributary streams to the Animas River is also included. The gradient map has stream segments that are color-coded based on relative variations in slope and .PDF format links to each stream gradient profile. Stream gradients were derived from U.S. Geological Survey 10-m digital elevation model data. This project was accomplished in support of the U.S. Geological Survey's Abandoned Mine Lands Initiative in the San Juan Mountains, Colorado.

Colorado↗

USGS2016

Database compilation for the geologic map of the San Francisco volcanic field, north-central Arizona

The main component of this publication is a geologic map database prepared using geographic information system (GIS) applications. The geodatabase of geologic points, lines, and polygons was produced as a compilation from five adjoining map sections originally published as printed maps in 1987 (see references in metadata). Four of the sections (U.S. Geological Survey Miscellaneous Field Studies Maps MF–1957, MF–1958, MF–1959, MF–1960) were created by scanning and geo-referencing stable base map material consisting of mylar positives. The final section (MF–1956) was compiled by hand tracing an enlargement of the available printed paper base map onto mylar using a #00 rapidograph pen, the mylar positive was then digitally scanned and geo-referenced. This method was chosen because the original basemap materials (mylar positives) for the MF–1956 section were unavailable at the time of this publication. Due to the condition of the available MF–1956 map section used as the base (which had previously been folded) the accuracy within the boundary of the MF–1956 section is presumed to be degraded in certain areas. The locations of the degraded areas and the degree of degradation within these areas is unclear. Final compilation of the database was completed using the ArcScan toolset, and the Editor toolset in ESRI ArcMap 10.1. Polygon topology was created from the lines and labels were added to the resultant geological polygons, lines, and points. Joseph A. Bard and David W. Ramsey updated and corrected the geodatabase, created the metadata and web presence, and provided the GIS-expertise to bring the geodatabase and metadata to completion. Included are links to files to view or print the original map sheets and the accompanying pamphlets. The orignial geologic maps were prepared under the Geothermal Research Program of the U.S. Geological Survey as a basis for interpreting the history of magmatic activity in the volcanic field. The San Francisco field, which is largely Pleistocene in age, is in northern Arizona, just north of the broad transition zone between the Colorado Plateau and the Basin and Range province. It is one of several dominantly basaltic volcanic fields of the late Cenozoic age situated near the margin of the Colorado Plateau. The volcanic field contains rocks ranging in composition from basalt to rhyolite—the products of eruption through Precambrian basement rocks and approximately a kilometer of overlying, nearly horizontal, Paleozoic and Mesozoic sedimentary rocks. About 500 km 3 of erupted rocks cover about 5,000 km 2 of predominantly Permian and locally preserved Triassic sedimentary rocks that form the erosionally stripped surface of the Colorado Plateau in Northern Arizona.

Arizona↗

USGS2011

The Alaska Geochemical Database: v. 1.0 - Geologic Materials

What is the AGDB?: The Alaska Geochemical Database (AGDB) is a new, comprehensive compilation of geologic, spatial, descriptive, mineralogical, and analytical geochemical data for samples collected in Alaska and surrounding waters by the U.S. Geological Survey (USGS) from 1962 to 2009. Data for geologic materials (rocks, minerals and mineral separates, soils, lake sediments, bulk stream sediments, and a variety of heavy-mineral concentrates) will be released as a two-sided DVD (USGS Digital Data Series DS 637 v. 1.0) in October of 2011. Future data releases will include water, organic and leachate samples. The AGDB contains all Alaskan data from USGS legacy databases (for example, the RASS and PLUTO systems), and all results produced by USGS in-house and contract chemistry laboratories through December 2009. The database includes geochemical data resulting from the reanalysis of archived materials, such as those from the Alaska Mineral Resource Assessment (AMRAP) and National Uranium Resource Evaluation (NURE) programs, for additional elements and by newer methods. Reanalyses include samples collected statewide as part of the National Geochemical Survey, and samples from a project across the Alaska Range (data released in 2010). The AGDB also contains data for geologic materials from Alaska submitted by USGS researchers to non-USGS and non-contract labs, and a variety of other Alaskan geologic materials samples. Quality Control: Data in the AGDB have undergone extensive quality control screening including searching field notes and maps for accurate location information, verifying media and sample type, linking analytical data to geologic parameters recorded by the submitter, and documenting sample preparation and analytical methods. Data Files The AGDB v. 1.0 two-sided DVD includes: * a 4.3 GB Microsoft Access® 2007 relational database (as two linked .mdb files); * the same database in Microsoft Access® 2003; * Microsoft Excel® spreadsheet tables (.xls files) and ASCII text files that display the results of common queries to the database (for example, Ag-Cr values for concentrate samples; rock samples by quadrangle); * references for analytical methods; * references to published data; and * metadata in three file formats. Data Availability: * The Alaska Geochemical Database will be available in a searchable, spatially referenced, online format at http://mrdata.usgs.gov/; estimated availability early 2012. * A 2012 update (AGDB v. 2.0) will include water, organic, leachate, and miscellaneous sample media. For More Information: On sample media or analytical methods: http://minerals.cr.usgs.gov/projects/analytical_chem/references.html Text prepared by Jeanine M. Schmidt and Matt Granitto Figure prepared by Nora Shew; Layout by Jeanine Schmidt Artwork on page 1 by Daniel Granitto (used by permission) The USGS Mineral Resources Program is the sole Federal provider of research and information on nonfuel mineral resources.

Fact Sheet↗

USGS1993

Quaternary geologic map of the Monterrey 4 degrees x 6 degrees quadrangle, United States

This map is part of the Quaternary Geologic Atlas of the United States (I-1420). It was first published as a printed edition in 1993. The geologic data have now been captured digitally and are presented here along with images of the printed map sheet and component parts as PDF files. The Quaternary Geologic Map of the Monterrey 4 degrees x 6 degrees Quadrangle was mapped as part of the Quaternary Geologic Atlas of the United States. The atlas was begun as an effort to depict the areal distribution of surficial geologic deposits and other materials that accumulated or formed during the past 2+ million years, the period that includes all activities of the human species. These materials are at the surface of the Earth. They make up the ground on which we walk, the dirt in which we dig foundations, and the soil in which we grow crops. Most of our human activity is related in one way or another to these surface materials that are referred to collectively by many geologists as regolith, the mantle of fragmental and generally unconsolidated material that overlies the bedrock foundation of the continent. The maps were compiled at 1:1,000,000 scale. In recent years, surficial deposits and materials have become the focus of much interest by scientists, environmentalists, governmental agencies, and the general public. They are the foundations of ecosystems, the materials that support plant growth and animal habitat, and the materials through which travels much of the water required for our agriculture, our industry, and our general well being. They also are materials that easily can become contaminated by pesticides, fertilizers, and toxic wastes. In this context, the value of the surficial geologic map is evident.

IMAP↗