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

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At least 973 records · Page 54Linked to original sources
USGS2002

Digital Bathymetric Model of Mono Lake, California

In 1986 and 1987, Pelagos Corporation of San Diego (now Racal Pelagos) undertook a bathymetric survey of Mono Lake in eastern California for the Los Angeles Department of Water and Power (DWP). The result of that survey was a series of maps at various scales and contour intervals. From these maps, the DWP hoped to predict consequences of the drop in lake level that resulted from their diversion of streams in the Mono Basin. No digital models, including shaded-relief and perspective-view renderings, were made from the data collected during the survey. With the permission of Pelagos Corporation and DWP, these data are used to produce a digital model of the floor of Mono Lake. The model was created using a geographic information system (GIS) to incorporate these data with new observations and measurements made in the field. This model should prove to be a valuable tool for enhanced visualization and analyses of the floor of Mono Lake.

Miscellaneous Field Studies Map↗
USGS2009

Evansville Area Earthquake Hazards Mapping Project (EAEHMP)— Progress report, 2008

Maps of surficial geology, deterministic and probabilistic seismic hazard, and liquefaction potential index have been prepared by various members of the Evansville Area Earthquake Hazard Mapping Project for seven quadrangles in the Evansville, Indiana, and Henderson, Kentucky, metropolitan areas. The surficial geologic maps feature 23 types of surficial geologic deposits, artificial fill, and undifferentiated bedrock outcrop and include alluvial and lake deposits of the Ohio River valley. Probabilistic and deterministic seismic hazard and liquefaction hazard mapping is made possible by drawing on a wealth of information including surficial geologic maps, water well logs, and in-situ testing profiles using the cone penetration test, standard penetration test, down-hole shear wave velocity tests, and seismic refraction tests. These data were compiled and collected with contributions from the Indiana Geological Survey, Kentucky Geological Survey, Illinois State Geological Survey, United States Geological Survey, and Purdue University. Hazard map products are in progress and are expected to be completed by the end of 2009, with a public roll out in early 2010. Preliminary results suggest that there is a 2 percent probability that peak ground accelerations of about 0.3 g will be exceeded in much of the study area within 50 years, which is similar to the 2002 USGS National Seismic Hazard Maps for a firm rock site value. Accelerations as high as 0.4-0.5 g may be exceeded along the edge of the Ohio River basin. Most of the region outside of the river basin has a low liquefaction potential index (LPI), where the probability that LPI is greater than 5 (that is, there is a high potential for liquefaction) for a M7.7 New Madrid type event is only 20-30 percent. Within the river basin, most of the region has high LPI, where the probability that LPI is greater than 5 for a New Madrid type event is 80-100 percent.

Indiana, Kentucky↗
USGS2006

Geologic map of the San Francisco Bay region

The rocks and fossils of the San Francisco Bay region reveal that the geology there is the product of millions of years at the active western margin of North America. The result of this history is a complex mosaic of geologic materials and structures that form the landscape. A geologic map is one of the basic tools to understand the geology, geologic hazards, and geologic history of a region. With heightened public awareness about earthquake hazards leading up to the 100th anniversary of the 1906 San Francisco earthquake, the U.S. Geological Survey (USGS) is releasing new maps of the San Francisco Bay Area designed to give residents and others a new look at the geologic history and hazards of the region. The “Geologic Map of the San Francisco Bay region” shows the distribution of geologic materials and structures, demonstrates how geologists study the age and origin of the rocks and deposits that we live on, and reveals the complicated geologic history that has led to the landscape that shapes the Bay Area.

California↗
USGS2019

U.S. Geological Survey EDMAP Program—Training the next generation of geologic mappers

Detailed geologic maps are the basis of nearly every Earth-science investigation and can be used for natural hazard mitigation, resource identification and exploration, infrastructure planning, and more. A component of the congressionally mandated National Cooperative Geologic Mapping Program, EDMAP is a partnership among the U.S. Geological Survey, the Association of American State Geologists, and participating colleges and universities that provides mentorship and training opportunities to geology students nationwide. Under the guidance of a faculty member, EDMAP supports upper level undergraduate and graduate students to gain meaningful experience working on 1-year geologic-mapping projects. Between 1996 and 2019, EDMAP funded research projects for more than 1,200 students at more than 160 universities. Every Federal dollar awarded through the EDMAP program is matched by the student’s university.

Fact Sheet↗
USGS1951

Diamond-drill exploration of the Rousseau talc prospect, Cambridge, Vermont, and the Barnes Hill prospect, Waterbury, Vermont

The Geological Survey carried out a program of diamond-drilling at two localities in Vermont during the period July-September 1950. The deposits chosen for drilling were two of the more promising talc deposits associated with ultramafic rocks of several that had been mapped earlier by the Geological Survey, but could not be evaluated accurately because critical data were lacking that could be obtained only by sub-surface exploration. The Rousseau talc prospect is in Cambridge township, Lamoille County, Vermont. Surface rights are owned by L. and N. N. Porter; mineral rights are owned by Eastern Magnesia Talc Co. Three drill holes encountered no talc; the other five penetrated from 2 to 110 feet of talc ore. The deposit lies on the west limb of the Green Mountain anticlinorium. The country rock consists of quartz-chlorite-sericite schist and chlorite-albite schist. The schistosity strikes slightly west of north and dips 20° - 40° to the west. The talc deposit is roughly lenticular, and although generally concordant in detail with the schistosity of the country rock, is slightly cross-cutting in overall relationship. The entire deposit is composed of Tit (talc-carbonate rock) and steatite, out is presumably derived from ultramafic igneous rooks which were first serpentinized. The dimensions of the lens are about 700 feet by 500 feet by 130 feet. The talc is of good quality and is suitable, either as a mine run product or as a flotation concentrate, for most industrial uses other than industrial steatite. No pencil stock was encountered. The Barnes hill talc prospect is in Waterbury township, Washington County, Vermont. Surface rights are divided among Donald P. and Glenola Brown, John Barnes, and Eastern Magnesia Talc Co. One drill hole at Barnes hill was barren. The other six penetrated about 20 to 140 feet of talc ore. The deposit lies on the east limb of the Green Mountain anticlinorium. The country rock outside of the ultramafic rock body consists of quartz-chlorite-sericite schist, chlorite-albite schist; and chlorite amphibolite, which strike generally about N, 20° E. and dip steeply to the east. The ultramafic body is elliptical in plan, about 1,600 feet long and 360 feet wide. The vertical dimension is unknown. The original ultramafic rock has been almost completely serpentinized and is extensively altered to grit and steatite. The talc ore is somewhat irregularly distributed throughout the ultramafic body, but it is possible to delineate with considerable confidence portions of the body that consist predominantly of ore. The largest ore bodies are in the eastern and northern parts of the ultramafic body. The ore contains more or less admixed serpentine, and so is only of intermediate to fairly good color (whiteness). It is suitable for many industrial uses in which purity and high whiteness are not necessary. No pencil stock was seen.

Vermont↗
USGS2017

Alaska and Yukon magnetic compilation, residual total magnetic field

This map is a compilation of aeromagnetic surveys over Yukon and eastern Alaska. Aeromagnetic surveys measure the total intensity of the earth's magnetic field. The field was measured by a magnetometer aboard an aircraft flown in parallel lines spaced at 200 m to 10000 m across the map area. The magnetic field reflects magnetic properties of bedrock and provides qualitative and quantitative information used in geological mapping. Understanding the geology will help geologists map the area, assist mineral/hydrocarbon exploration activities, and provide useful information necessary for communities, aboriginal associations, and government to make land use decisions. This survey was flown to improve our knowledge of the area. It will support ongoing geological mapping and resource assessment.

Alaska, Yukon↗
USGS2012

Bathymetry and capacity of Blackfoot Reservoir, Caribou County, Idaho, 2011

The U.S. Geological Survey (USGS), in cooperation with the Shoshone-Bannock Tribes, surveyed the bathymetry and selected above-water sections of Blackfoot Reservoir, Caribou County, Idaho, in 2011. Reservoir operators manage releases from Government Dam on Blackfoot Reservoir based on a stage-capacity relation developed about the time of dam construction in the early 1900s. Reservoir operation directly affects the amount of water that is available for irrigation of agricultural land on the Fort Hall Indian Reservation and surrounding areas. The USGS surveyed the below-water sections of the reservoir using a multibeam echosounder and real-time kinematic global positioning system (RTK-GPS) equipment at full reservoir pool in June 2011, covering elevations from 6,090 to 6,119 feet (ft) above the North American Vertical Datum of 1988 (NAVD 88). The USGS used data from a light detection and ranging (LiDAR) survey performed in 2000 to map reservoir bathymetry from 6,116 to 6,124 ft NAVD 88, which were mostly in depths too shallow to measure with the multibeam echosounder, and most of the above-water section of the reservoir (above 6,124 ft NAVD 88). Selected points and bank erosional features were surveyed by the USGS using RTK-GPS and a total station at low reservoir pool in September 2011 to supplement and verify the LiDAR data. The stage-capacity relation was revised and presented in a tabular format. The datasets show a 2.0-percent decrease in capacity from the original survey, due to sedimentation or differences in accuracy between surveys. A 1.3-percent error also was detected in the previously used capacity table and measured water-level elevation because of questionable reference elevation at monitoring stations near Government Dam. Reservoir capacity in 2011 at design maximum pool of 6,124 ft above NAVD 88 was 333,500 acre-ft.

Idaho↗
USGS2009

Michigan magnetic and gravity maps and data: A website for the distribution of data

This web site provides the best available, public-domain, aeromagnetic and gravity data in the State of Michigan and merges these data into composite grids that are available for downloading. The magnetic grid is compiled from 25 separate magnetic surveys that have been knit together to form a single composite digital grid and map. The magnetic survey grids have been continued to 305 meters (1,000 feet) above ground and merged together to form the State compilation. A separate map shows the location of the aeromagnetic surveys, color-coded to the survey flight-line spacing. In addition, a complete Bouguer gravity anomaly grid and map were generated from more than 20,000 gravity station measurements from 33 surveys. A table provides the facts about each gravity survey where known.

Michigan↗
USGS2000

Digital geologic map of the Coeur d'Alene 1:100,000 quadrangle, Idaho and Montana

Between 1961 and 1969, Alan Griggs and others conducted fieldwork to prepare a geologic map of the Spokane 1:250,000 map (Griggs, 1973). Their field observations were posted on paper copies of 15-minute quadrangle maps. In 1999, the USGS contracted with the Idaho Geological Survey to prepare a digital version of the Coeur d’Alene 1:100,000 quadrangle. To facilitate this work, the USGS obtained the field maps prepared by Griggs and others from the USGS Field Records Library in Denver, Colorado. The Idaho Geological Survey (IGS) digitized these maps and used them in their mapping program. The mapping focused on field checks to resolve problems in poorly known areas and in areas of disagreement between adjoining maps. The IGS is currently in the process of preparing a final digital spatial database for the Coeur d’Alene 1:100,000 quadrangle. However, there was immediate need for a digital version of the geologic map of the Coeur d’Alene 1:100,000 quadrangle and the data from the field sheets along with several other sources were assembled to produce this interim product. This interim product is the digital geologic map of the Coeur d’Alene 1:100,000 quadrangle, Idaho and Montana. It was compiled from the preliminary digital files prepared by the Idaho Geological, and supplemented by data from Griggs (1973) and from digital databases by Bookstrom and others (1999) and Derkey and others (1996). The resulting digital geologic map (GIS) database can be queried in many ways to produce a variety of geologic maps. Digital base map data files (topography, roads, towns, rivers and lakes, etc.) are not included: they may be obtained from a variety of commercial and government sources. This database is not meant to be used or displayed at any scale larger than 1:100,000 (e.g., 1:62,500 or 1:24,000). The digital geologic map graphics (of00-135_map.pdf) that are provided are representations of the digital database. The map area is located in north Idaho. This open-file report describes the geologic map units, the methods used to convert the geologic map data into a digital format, the ArcInfo GIS file structures and relationships, and explains how to download the digital files from the U.S. Geological Survey public access World Wide Web site on the Internet.

Idaho, Montana↗
USGS1960

The chief oxide-burgin area discoveries, East Tintic district, Utah; A case history

The Burgin shaft is in the Chief Oxide area of the E. Tintic district, Utah, and is about a mile E. of any previously known ore bodies; workings from it are currently developing a substantial amount of commercial Pb-Zn ore in several blind ore bodies that lie in folded Paleozoic carbonate rock concealed beneath a blanket of Eocene lava. This area was mapped by Tower and Smith of the U.S. Geological Survey in 1897 and again by Lindgren and Loughlin in 1911, but no detailed work was done until after 1943 when a field party headed by T.S. Lovering began a study of the entire E. Tintic district. The history of the development of exploration concepts is summarized under Historical Summary. The E. Tintic mining district is in the E.-central part of a N.-trending fault-block mountain range near the eastern margin of the Great Basin; dominant structures of the range are a N.-trending syncline on the W. and a less well exposed anticline on the E. Both folds are cut by an intersecting system of transcurrent strike-slip faults and by minor thrust faults and normal faults of moderate displacement. A strong W.-dipping thrust fault cuts the anticline a short distance E. of the fold axis, but is hidden by Eocene lava throughout the E. Tintic district. The pre-Tertiary rocks range from Lower Cambrian to Upper Mississippian and exceed 7,000 ft. in total thickness; they are dominantly marine limestone and dolomite except for a thick basal Cambrian quartzite. The Tertiary rocks are chiefly dacitic lavas and pyroclastic deposits that are intruded by moderately persistent dikes and irregular bodies of monzonite and quartz porphyry. Nearly all the faulting and folding took place before the extrusion of the lavas on a rugged Eocene erosion surface. At about the time of the intrusion of monzonitic magma, many of the faults in the Paleozoic rock were re-opened and in the overlying lava some fracturing took place which was later accented by hydrothermal alteration. Most of the ore mined in the E. Tintic district has come from Pb-Zn-Ag replacement bodies in shattered Jasperoidized hydrothermal dolomite at the intersection of low angle faults and steep mineralized NE.-trending cross fractures. The U.S. Geological Survey studies of 1943 to 1957 concentrated on detailed mapping of geology and alteration in the E. Tintic district, together with field and laboratory studies of the relation of alteration to stages of mineralization and ore deposition. Trenching and core drilling were carried on after World War II to aid in interpreting the subrhyolite geology, and the Chief Oxide area was 1 of 4 localities tested by drilling. Study of the fossils, lithology, and alteration shown here in a deep drill core, together with the knowledge of the regional geology, led to an essentially correct interpretation of subrhyolite structure in the strongly discordant underlying Paleozoic rocks in which a mineralized tear fault cuts a strong thrust fault, and to the conclusion that ore stage mineralization was present in substantial amounts in the Paleozoic rocks below the Chief Oxide alteration patch in the quartz latite lava. Subsequent geothermal and geochemical work strengthened this conclusion, and the recent development work of the Bear Creek Mining Company, which sank the Burgin shaft, has shown the presence of Pb-Zn-Ag ore of commercial grade in substantial amount in blind ore bodies below the lava blanket in the Chief Oxide area.

Utah↗
USGS1994

Map adventures

Map Adventures, with seven accompanying lessons, is appropriate for grades K-3. Students will learn basic concepts for visualizing objects from different perspectives and how to understand /and use maps.

General Information Product↗
USGS1989

Geologic map of Yosemite National Park and vicinity, California

This digital map database represents the general distribution of bedrock and surficial deposits of the Yosemite National Park vicinity. It was produced directly from the file used to create the print version in 1989. The Yosemite National Park region is comprised of portions of 15 7.5 minute quadrangles. The original publication of the map in 1989 included the map, described map units and provided correlations, as well as a geologic summary and references, all on the same sheet. The database delineates map units that are identified by general age and lithology following the stratigraphic nomenclature of the U.S. Geological Survey. The scale of the source maps limits the spatial resolution (scale) of the database to 1:125,000 or smaller.

IMAP↗
USGS2000

Geologic map of the Grand Canyon 30' x 60' quadrangle, Coconino and Mohave Counties, northwestern Arizona

This digital map database, compiled from previously published and unpublished data as well as new mapping by the author, represents the general distribution of bedrock and surficial deposits in the map area. Together with the accompanying pamphlet, it provides current information on the geologic structure and stratigraphy of the Grand Canyon area. The database delineates map units that are identified by general age and lithology following the stratigraphic nomenclature of the U.S. Geological Survey. The scale of the source maps limits the spatial resolution (scale) of the database to 1:100,000 or smaller.

IMAP↗
USGS2000

Geologic map and map database of the Palo Alto 30' x 60' quadrangle, California

This digital map database, compiled from previously published and unpublished data, and new mapping by the authors, represents the general distribution of bedrock and surficial deposits in the mapped area. Together with the accompanying text file (pamf.ps, pamf.pdf, pamf.txt), it provides current information on the geologic structure and stratigraphy of the area covered. The database delineates map units that are identified by general age and lithology following the stratigraphic nomenclature of the U.S. Geological Survey. The scale of the source maps limits the spatial resolution (scale) of the database to 1:62,500 or smaller.

California↗
USGS2001

Geologic map and map database of the Spreckels 7.5-minute Quadrangle, Monterey County, California

Introduction The Spreckels quadrangle lies at the north end of the Sierra de Salinas and extends from the Salinas Valley on the northeast across Los Laurelles Ridge south to Carmel Valley, an intermontane valley that separates the Santa Lucia Range from the Sierra de Salinas (fig. 1). The Toro Regional Park occupies the east-central part of the quadrangle, whereas the former Fort Ord Military Reservation covers the northwestern part of the area and is the probable locus of future development. Subdivisions largely occupy the older floodplain of Toro Creek and the adjacent foothills, with less dense development along the narrower canyons of Corral de Tierra and San Benancio Gulch to the south. The foothills southwest of the Salinas River are the site of active residential development. Geologically, the study area has a crystalline basement of Upper Cretaceous granitic rocks of the Salinian block and older metasedimentary rocks of the schist of the Sierra de Salinas of probable Cretaceous age. Resting nonconformably upon these basement rocks is a sedimentary section that ranges in age from middle Miocene to Holocene and has a composite thickness of as much as 1,200 m. One of the purposes of the present study was to investigate the apparent lateral variation of the middle to upper Miocene sections from the typical porcelaneous and diatomaceous Monterey Formation of the Monterey and Seaside quadrangles to the west (Clark and others, 1997) to a thick marine sandstone section in the eastern part of the Spreckels quadrangle. Liquefaction, which seriously affected the Spreckels area in the 1906 San Francisco earthquake (Lawson, 1908), and landsliding are the two major geological hazards of the area. The landslides consist mainly of older large slides in the southern and younger debris flows in the northern part of the quadrangle. This digital map database, compiled from previously published and unpublished data, and new mapping by the authors, represents the general distribution of bedrock and surficial deposits in the mapped area. Together with the accompanying text file (skmf.txt, skmf.pdf, or skmf.ps), it provides current information on the geologic structure and stratigraphy of the area covered. The database delineates map units that are identified by general age and lithology following the stratigraphic nomenclature of the U.S. Geological Survey. The scale of the source maps limits the spatial resolution (scale) of the database to 1:24,000 or smaller.

Miscellaneous Field Studies Map↗
USGS2001

Geologic map of the Silver Lake Quadrangle, Cowlitz County, Washington

This digital map database, compiled from previously published and unpublished data, and new mapping by the authors, represents the general distribution of bedrock and surficial deposits of the Silver lake 7.5 minute quadrangle. The database delineates map units that are identified by general age and lithology following the stratigraphic nomenclature of the U.S. Geological Survey. The scale of the source maps limits the spatial resolution (scale) of the database to 1:24,000 or smaller.

Miscellaneous Field Studies Map↗
USGS2001

Geologic maps and structure sections of the southwestern Santa Clara Valley and southern Santa Cruz Mountains, Santa Clara and Santa Cruz Counties, California

This digital map database, compiled from previously published and unpublished data, and new mapping by the authors, represents the general distribution of bedrock and surficial deposits in the mapped area. Together with the accompanying text file (scvmf.ps, scvmf.pdf, scvmf.txt), it provides current information on the geologic structure and stratigraphy of the area covered. The database delineates map units that are identified by general age and lithology following the stratigraphic nomenclature of the U.S. Geological Survey. The scale of the source maps limits the spatial resolution (scale) of the database to 1:24,000 or smaller.

Miscellaneous Field Studies Map↗
USGS2002

Geologic map and map database of western Sonoma, northernmost Marin, and southernmost Mendocino counties, California

This digital map database, compiled from previously published and unpublished data, and new mapping by the authors, represents the general distribution of bedrock and surficial deposits in the mapped area. Together with the accompanying text file (wsomf.ps, wsomf.pdf, wsomf.txt), it provides current information on the geologic structure and stratigraphy of the area covered. The database delineates map units that are identified by general age and lithology following the stratigraphic nomenclature of the U.S. Geological Survey. The scale of the source maps limits the spatial resolution (scale) of the database to 1:62,500 or smaller.

Miscellaneous Field Studies Map↗