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At least 721 records · Page 40Linked to original sources
USGS2010

Bedrock geologic map of the Montpelier and Barre West quadrangles, Washington and Orange Counties, Vermont

The bedrock geology of the Montpelier and Barre West quadrangles consists of Silurian and Devonian metasedimentary rocks of the Connecticut Valley-Gaspe synclinorium (CVGS) and metasedimentary, metavolcanic, and metaintrusive rocks of the Cambrian and Ordovician Moretown and Cram Hill Formations. Devonian granite dikes occur throughout the two quadrangles but are more abundant in the Silurian and Devonian rocks. The pre-Silurian rocks are separated from the rocks of the CVGS by the informally named 'Richardson Memorial Contact,' historically interpreted as either an unconformity or a fault. The results of this report represent mapping by G.J. Walsh, Jonathan Kim, and M.H. Gale from 2002 to 2005. S.M. King assisted Kim and Gale from 2002 to 2003. A.M. Satkoski (Indiana University) assisted Walsh, and L.R. Pascale (University of Vermont) and C.M. Orsi (Middlebury College) assisted Kim and Gale as summer interns in 2003. This study was designed to map the bedrock geology in the area. This map supersedes a preliminary map of the Montpelier quadrangle (Kim, Gale, and others, 2003). A companion study in the Barre West quadrangle (Walsh and Satkoski, 2005) determined the levels of naturally occurring radioactivity in the bedrock from surface measurements at outcrops during the course of 1:24,000-scale geologic mapping to identify which rock types were potential sources of radionuclides. Results of that study indicate that the carbonaceous phyllites in the CVGS have the highest levels of natural radioactivity.

Vermont↗
USGS2003

Geologic map of the Hiller Mountain Quadrangle, Clark County, Nevada, and Mohave County, Arizona

Map Scale: 1 :24,000 Map Type: colored geologic map The Hiller Mountains Quadrangle straddles Virgin Canyon in the eastern part of Lake Mead. Proterozoic gneisses and granitoid rocks underlie much of the quadrangle . They are overlain by upper Miocene basin-filling deposits of arkosic conglomerate, basalt, and the overlying Hualapai Limestone. Inception of the Colorado River followed deposition of the Hualapai Limestone and caused incision of the older rocks. Fluvial gravel deposits indicate various courses of the early river across passes through highlands of the Gold Butte- Hiller Mountains-White Hills structural block . Faults and tilted rocks in the quadrangle record tectonic extension that climaxed in middle Miocene time.

Report↗
USGS2003

Geologic map of the Fremont quadrangle, Shannon, Carter, and Oregon Counties, Missouri

The bedrock exposed in the Fremont Quadrangle, Missouri, comprises Early Ordovician aged dolomite, sandstone, and chert. The sedimentary rocks are nearly flat-lying except where they are adjacent to faults. The carbonate rocks are karstified and the area contains numerous sinkholes, springs, caves, and losing-streams. This map is one of several being produced under the U.S. Geological Survey National Cooperative Geologic Mapping Program to provide geologic data applicable to land-use problems in the Ozarks of south-central Missouri. Ongoing and potential industrial and agricultural development in the Ozarks region has presented issues of ground-water quality in karst areas. National Park in this region (Ozark National Scenic Riverways, Missouri) is concerned about the effects of activities in areas outside of their stewardship on the water resources that define the heart of this Park. This task applies geologic mapping and karst investigations to address issues surrounding competing land use in south-central Missouri. This task keeps geologists from the USGS associated with the park and allows the Parks to utilize USGS expertise and aid the NPS on how to effectively use geologic maps for Park management. For more information see: http://geology.er.usgs.gov/eespteam/Karst/index.html

IMAP↗
USGS2011

Preliminary geologic map of the Bowen Mountain quadrangle, Grand and Jackson Counties, Colorado

The map shows the geology of an alpine region in the southern Never Summer Mountains, including parts of the Never Summer Wilderness Area, the Bowen Gulch Protection Area, and the Arapaho National Forest. The area includes Proterozoic crystalline rocks in fault contact with folded and overturned Paleozoic and Mesozoic sedimentary rocks and Upper Cretaceous(?) and Paleocene Middle Park Formation. The folding and faulting appears to reflect a singular contractional deformation (post-Middle Park, so probably younger than early Eocene) that produced en echelon structural uplift of the Proterozoic basement of the Front Range. The geologic map indicates there is no through-going \"Never Summer thrust\" fault in this area. The middle Tertiary structural complex was intruded in late Oligocene time by basalt, quartz latite, and rhyolite porphyry plugs that also produced minor volcanic deposits; these igneous rocks are collectively referred to informally as the Braddock Peak intrusive-volcanic complex whose type area is located in the Mount Richthofen quadrangle immediately north (Cole and others, 2008; Cole and Braddock, 2009). Miocene boulder gravel deposits are preserved along high-altitude ridges that probably represent former gravel channels that developed during uplift and erosion in middle Tertiary time.

Colorado↗
USGS2009

Bedrock geologic map of the Old Lyme quadrangle, New London and Middlesex Counties, Connecticut

The bedrock geology of the Old Lyme quadrangle consists of Neoproterozoic and Permian gneisses and granites of the Gander and Avalon terranes, Silurian metasedimentary rocks of the Merrimack terrane, and Silurian to Devonian metasedimentary rocks of uncertain origin. The Avalon terrane rocks crop out within the Selden Neck block, and the Gander terrane rocks crop out within the Lyme dome. The Silurian to Devonian rocks crop out between these two massifs. Previous mapping in the Old Lyme quadrangle includes the work by Lawrence Lundgren, Jr. Lundgren's work provides an excellent resource for rock descriptions and detailed modal analyses of rock units that will not be duplicated in this current report. New research that was not covered in detail by Lundgren is the focus of this report and includes (1) evaluation of the rocks in the core of the Lyme dome in an effort to subdivide units in this area; (2) structural analysis of foliations and folds in and around the Lyme dome; (3) geochronology of selected units within the Lyme dome; and (4) analysis of joints and the fracture properties of the rocks.

Connecticut↗
USGS2006

Preliminary Surficial Geologic Map of the Mesquite Lake 30' X 60' Quadrangle, California and Nevada

The Quaternary surficial geologic map of the Mesquite Lake, California-Nevada 30'X60' quadrangle depicts deposit age and geomorphic processes of erosion and deposition, as identified by a composite of remote sensing investigations, laboratory analyses, and field work, in the arid to semi-arid Mojave Desert area, straddling the California-Nevada border. Mapping was motivated by the need to address pressing scientific and social issues such as understanding and predicting the effects of climate and associated hydrologic changes, human impacts on landscapes, ecosystem function, and natural hazards at a regional scale. As the map area lies just to the south of Las Vegas, Nevada, a rapidly expanding urban center, land use pressures and the need for additional construction materials are forecasted for the region. The map contains information on the temporal and spatial patterns of surface processes and hazards that can be used to model specific landscape applications. Key features of the geologic map include: (1) spatially extensive Holocene alluvial deposits that compose the bulk of Quaternary units (~25%), (2) remote sensing and field studies that identified fault scarps or queried faults in the Kingston Wash area, Shadow Mountains, southern Pahrump Valley, Bird Spring Range, Lucy Gray Mountains and Piute Valley, (3) a lineament indicative of potential fault offset is located in Mesquite Valley, (4) active eolian dunes and sand ramps located on the east side of Mesquite, Ivanpah, and Hidden Valleys adjacent to playas, (4) groundwater discharge deposits in southern Pahrump Valley, Spring Mountains, and Lucy Gray Mountains and (5) debris-flow deposits spanning almost the entire Quaternary period in age.

Open-File Report↗
USGS1977

Geologic map of the Eridania Quadrangle of Mars

The Eridania quadrangle is located within the densely cratered terrain of the southern hemisphere of Mars, east of the large circular Hellas Basin. The areas contain three distinct physiographic provinces that div ide the quadrangle into latitud in al belts. The northern part of the quadrangle is dominated by cratered upland plateau, the central part by plains, the southern part by a mottled surface of rugged topography and a high density of craters subdued by erosion. In general, the oldest geologic unit occurs in the upland terrain, the youngest in the central lowlands. Large contrast in albedo were observed on Mars from Earth long before Mariner spaceflight missions. The most conspic uous of these features within the quadrangle are areas of low albedo in the north and in the south that corresponds to the two main belts of high-relief terrain. The intervening region of high albedo corresponds to the central plains belt, also an area of recurrent seasonal frost. The southern polar cap extends to about 50 ˚ S lat and includes all of the southern belt of high relief.

IMAP↗
USGS2002

Geologic map of the Corona South 7.5' quadrangle, Riverside and Orange counties, California

Open-File Report 01-021 contains a digital geologic map database of the Corona South 7.5’ quadrangle, Riverside County, California that includes: 1. ARC/INFO (Environmental Systems Research Institute, http://www.esri.com) version 7.2.1 coverages of the various elements of the geologic map. 2. A Postscript file to plot the geologic map on a topographic base, and containing a Correlation of Map Units diagram (CMU), a Description of Map Units (DMU), and an index map. 3. Portable Document Format (.pdf) files of: a. A Readme file; includes in Appendix I, data contained in crs_met.txt b. The same graphic as plotted in 2 above. Test plots have not produced 1:24,000-scale map sheets. Adobe Acrobat page size setting influences map scale. The Correlation of Map Units and Description of Map Units is in the editorial format of USGS Geologic Investigations Series (I-series) maps but has not been edited to comply with I-map standards. Within the geologic map data package, map units are identified by standard geologic map criteria such as formation-name, age, and lithology. Where known, grain size is indicated on the map by a subscripted letter or letters following the unit symbols as follows: lg, large boulders; b, boulder; g, gravel; a, arenaceous; s, silt; c, clay; e.g. Qyfa is a predominantly young alluvial fan deposit that is arenaceous. Multiple letters are used for more specific identification or for mixed units, e.g., Qfysa is a silty sand. In some cases, mixed units are indicated by a compound symbol; e.g., Qyf2sc. Marine deposits are in part overlain by local, mostly alluvial fan, deposits and are labeled Qomf. Grain size follows f. Even though this is an Open-File Report and includes the standard USGS Open-File disclaimer, the report closely adheres to the stratigraphic nomenclature of the U.S. Geological Survey. Descriptions of units can be obtained by viewing or plotting the .pdf file (3b above) or plotting the postscript file (2 above).

California↗
USGS2001

Geologic map of the Winona Quadrangle, Shannon County, Missouri

The bedrock exposed in the Winona Quadrangle, Missouri, comprises Mesoproterozoic aged volcanic rocks overlain by Late Cambrian and Early Ordovician aged dolomite, sandstone, and chert. The sedimentary rocks are nearly flat-lying except where they drape around knobs of the volcanic rocks or where they are adjacent to faults. The carbonates are karstified and the area contains numerous sinkholes, springs, caves, and losing-streams. This map is one of several being produced under the U.S. Geological Survey National Cooperative Geologic Mapping Program to provide geologic data applicable to land-use problems in the Ozarks of south-central Missouri. Ongoing and potential industrial and agricultural development in the Ozarks region has presented issues of ground-water quality in karst areas. A National Park in this region (Ozark National Scenic Riverways, Missouri ) is concerned about the effects of activities in areas outside of their stewardship on the water resources that define the heart of this Park. This task applies geologic mapping and karst investigations to address issues surrounding competing land use in south-central Missouri. This task keeps geologists from the USGS associated with the park and allows the Parks to utilize USGS expertise and aid the NPS on how to effectively use geologic maps for Park management. For more information see: http://geology.er.usgs.gov/eespteam/Karst/index.html

IMAP↗
USGS1978

Geologic map of the Thaumasia Quadrangle of Mars

The Thaumasia quadrangle lies on the south flank of the Tharsis dome (Hord and others, 1974), a large bulge in the crust of Mars extending more than 5,000 km northward from the center of the quadrangle. The major structure imposes a generally southward slope across the entire quadrangle. Topography along the east-central border of the Thaumasia quadrangle exhibits curved scarps and lowlands concentric with the Argyre basin. Four regions within the Thaumasia quadrangle are defined on the basis of the dominant geologic unit exposed. Three of these regions form arcuate patterns around the south flank of the Tharsis dome, and the fourth is a arcuate region concentric with the Argyre basin.

IMAP↗
USGS2000

Digital geologic map of the Butler Peak 7.5' quadrangle, San Bernardino County, California

Open-File Report 00-145, is a digital geologic map database of the Butler Peak 7.5' quadrangle that includes (1) ARC/INFO ( Environmental Systems Research Institute ) version 7.2.1 Patch 1 coverages, and associated tables, (2) a Portable Document Format (.pdf) file of the Description of Map Units, Correlation of Map Units chart, and an explanation of symbols used on the map, btlrpk_dcmu.pdf, (3) a Portable Document Format file of this Readme, btlrpk_rme.pdf (the Readme is also included as an ascii file in the data package), and (4) a PostScript plot file of the map, Correlation of Map Units, and Description of Map Units on a single sheet, btlrpk.ps. No paper map is included in the Open-File report, but the PostScript plot file (number 4 above) can be used to produce one. The PostScript plot file generates a map, peripheral text, and diagrams in the editorial format of USGS Geologic Investigation Series (I-series) maps.

California↗
USGS1972

Geologic map of the Fracastorius Quadrangle of the Moon

The multi-ringed Nectaris basin ( Hartmann and Kuiper, 1962) dominates the Fracastorius quadrangle. The basin is 840 km across as measured from the outermost ring and lies athwart four quadrangles. Frac astorius , the southeastern quadrangle , straddles the three rings of the basin (fig. 1 ). In this quadrangle most pre- Imbri an structures and many depositions were formed by the Nectaris impact. Furthermore, the emplacement of many younger deposi ts was controlled by basin structures and locally by probable multi-ring structures related to the Fecunditatis basin center ed northeast of the quadrangle. Other geologic features in the area include diverse mantling deposits and both primary impact craters and secondary impact craters produced by ejecta from distant impacts .

IMAP↗
USGS1987

The Alaska Mineral Resource Assessment Program: Background information to accompany folio of geologic and mineral resource maps of the Circle quadrangle, Alaska

The geology, geochemistry, geophysics, and Landsat imagery of the Circle quadrangle were investigated by an interdisciplinary research team for the purpose of assessing the mineral potential of the area. The quadrangle covers approximately 15,765 km 2 in east-central Alaska; most of it is included in the mountainous Yukon-Tanana Upland physiographic division, but the northernmost part is in the low-lying Yukon Flats section. The Circle mining district, in the east-central part of the quadrangle, has been a major producing area of placer gold since its discovery in 1893. For descriptive purposes, the Circle quadrangle is divided into three areas: the northwest Circle quadrangle, the area north of the Tintina fault zone, and the area south of the Tintina fault zone. The Tintina fault zone extends northwesterly through the northern part of the quadrangle. The northwest Circle quadrangle contains mostly folded and faulted, slightly metamorphosed sedimentary rocks that are intruded by Tertiary granitic plutons. In the northern part of the area north of the Tintina fault zone (Little Crazy Mountains and northern east Crazy Mountains), the rocks consist primarily of the gabbro and basalt of the Circle Volcanics and minor associated chert, graywacke, and limestone. Elsewhere in this area (south of the Circle Volcanics and in the western Crazy Mountains), the rocks are mostly slightly metamorphosed Paleozoic sedimentary rocks that have been folded and faulted. Rocks in the largest part of the quadrangle, the area south of the Tintina fault zone, consist largely of pelitic rocks that are regionally metamorphosed to greenschist and amphibolite facies. Felsic plutons, mostly Tertiary in age, occur throughout the area. The metamorphic rocks are separated from sedimentary rocks on the northwest by thrust faulting. The aeromagnetic and gravity data show clear differences between the areas north and south of the Tintina fault zone. The metamorphic terrane to the south has low overall gravity and local gravity lows over exposed granitic plutons. It is hypothesized that magnetic chlorite schist infolded with nonmagnetic quartzite and schist account for east-northeast-trending magnetic highs that approximately parallel the regional strike of the most prominent foliation in the metamorphic rocks. North of the Tintina fault zone, the Circle Volcanics are characterized by high gravity and east-west-trending magnetic highs. The Tintina fault zone has an intense magnetic high near the western margin of the Circle quadrangle overlying the magnetic granodiorite of the Victoria Mountain pluton. A magnetic high near Circle Hot Springs is less intense, but broader, and could reflect a buried magnetic pluton similar to that of the Victoria Mountain pluton. Computer-enhanced Landsat images of the Circle quadrangle show trends and patterns of concentrations of linear features. Features trending northeast-southwest predominate throughout the quadrangle; northwest-southeast-trending linear features are found mostly south of the Tintina fault zone. High concentrations of linear features were not found to correspond to areas of known mineralization in any consistent or significant way that could presently be used in locating areas of mineralization. Geochemical and mineralogical studies of stream sediment and heavy-mineral concentrates from the Circle quadrangle identify areas of anomalous concentrations of metallic elements, including gold, silver, tin, tungsten, lead, antimony, zinc, thorium, uranium, and beryllium. The data delineate areas of known mineral occurrences and areas that may contain undiscovered mineral resources. To date, placer gold has been the only significant metallic mineral resource from the Circle quadrangle, but the general geologic setting, especially the presence of post-orogenic plutons, is similar to that of regions that contain tin greisen deposits, tungsten skarn deposits, lode gold deposits in metasedimentary rocks, and uranium vein deposits. Six areas or tracts were identified in which such deposits might occur, and two more tracts were delineated as possible for the occurrence of shale-hosted Lead-zinc deposits. The discovery of two diamonds in the gravels of Cooked Creek point to the slight possibility of finding placer or lode diamond deposits. Although most of the past and present gold mining has taken place in four areas in the quadrangle, a sedimentary basin near the town of Central was identified as possibly containing buried placer gold deposits or sedimentary uranium deposits.

Alaska↗
USGS2004

Geologic map of the Kanab 30' x 60' quadrangle, Utah and Arizona

The 1:100,000-scale geologic map of the sparsely populated Kanab 30' x 60' quadrangle in southernmost Utah and a narrow strip in northernmost Arizona delineates 17 formations and numerous subdivisions of sedimentary rock units of Permian, Triassic, Jurassic, Cretaceous, and Tertiary ages; 12 Quaternary alluvial, eolian, and mass-wasting units; and Quaternary basaltic igneous rocks and vents.Units within the Straight Cliffs Formation are correlated with those of the Kaiparowits Plateau. Palynological edidence indicates that the Kaiparowits(?) Formation is older than the type formation in the Kaiparowits Plateau. Structures include parts of the Sevier, Kanab Creek, Johnson Canyon, and Paunsaugunt fault zones. Regional dip is generally northeast at very low angles. Coal beds are presentin the upper unit of the Straight Cliffs Formation, in the Tropic Shale, and in the Dakota Formation.

IMAP↗
USGS2005

Preliminary geologic map of the Los Angeles 30' x 60' quadrangle, Southern California

This data set maps and describes the geology of the Los Angeles 30? x 60? quadrangle, southern California. Compilation of the Los Angeles quadrangle is based upon published mapping at scales of 1:12,000 and smaller, unpublished mapping at scales of 1:12,000 and smaller, with reconnaissance mapping by the compilers to resolve some edge-matching problems. The Los Angeles 30' x 60' quadrangle covers approximately 5,000 km2 including some of the most densely populated urban and suburban areas of the southern California megalopolis. It extends about 90 km E-W and about 55 km N-S, from Fillmore and Thousand Oaks in the west to Vincent in the northeast and Montebello in the southeast, and includes urban San Gabriel Valley and San Gabriel Mountain foothill communities from Monrovia to Pasadena, as well as Glendale, downtown Los Angeles, Hollywood, Santa Monica, Malibu, in addition to all the communities in the San Fernando Valley, Simi Valley, and the upper Santa Clara River Valley. From the 2000 Census, the population of these urban and suburban areas totals approximately 5.6 million, and estimates of property value total hundreds of billions of dollars. Residents and transient visitors are subject to potential hazards from earthquakes, debris flows and other landslides, floods, wildfires, subsidence from ground water and petroleum withdrawal, and swelling soils; and coastal areas are exposed to flooding and erosion by storm and tsunami waves. Topographic relief ranges from about one hundred meters sub sea (in Santa Monica Bay) to more than 2,000 meters above sea level at Pacifico Mountain in the high San Gabriel Mountains. In addition to the populated area, the quadrangle includes significant areas of wilderness in the Angeles and Los Padres National Forests, in the Santa Monica Mountains National Recreation Area, and the Sespe Condor Sanctuary. The geologic map illustrates the general distribution of the rocks and surficial deposits in the area and their structural and stratigraphic relations to one another. The principal characteristics of the map units are described and are part of the database. The map provides a regional geologic framework as an aid to better evaluations of the potential for hazard from active earth processes. It synthesizes and combines studies by many earth scientists. Most of the source maps are at more detailed scales than 1:100,000, and we utilized the most detailed source materials available. We have not attempted to resolve all problems of stratigraphic correlation and nomenclature. In most areas we have retained the unit designations of source-map authors, but in some areas, particularly in the igneous-metamorphic complex of the San Gabriel Mountains, some unit designations have been changed. Hopefully, this map will stimulate further work to describe and correlate the many units within the scope of a more coherent, more accurate geologic history.

California↗
USGS2011

Geologic map of the Metis Mons quadrangle (V–6), Venus

The Metis Mons quadrangle (V–6) in the northern hemisphere of Venus (lat 50° to 75° N., long 240° to 300° E.) includes a variety of coronae, large volcanoes, ridge and fracture (structure) belts, tesserae, impact craters, and other volcanic and structural features distributed within a plains setting, affording study of their detailed age relations and evolutionary development. Coronae in particular have magmatic, tectonic, and topographic signatures that indicate complex evolutionary histories. Previously, the geology of the map region has been described either in general or narrowly focused investigations. Based on Venera radar mapping, a 1:15,000,000-scale geologic map of part of the northern hemisphere of Venus included the V–6 map region and identified larger features such as tesserae, smooth and hummocky plains materials, ridge belts, coronae, volcanoes, and impact craters but proposed little relative-age information. Global-scale mapping from Magellan data identified similar features and also determined their mean global ages with crater counts. However, the density of craters on Venus is too low for meaningful relative-age determinations at local to regional scales. Several of the coronae in the map area have been described using Venera data (Stofan and Head, 1990), while Crumpler and others (1992) compiled detailed identification and description of volcanic and tectonic features from Magellan data. The main purpose of this map is to reconstruct the geologic history of the Metis Mons quadrangle at a level of detail commensurate with a scale of 1:5,000,000 using Magellan data. We interpret four partly overlapping stages of geologic activity, which collectively resulted in the formation of tesserae, coronae (oriented along structure belts), plains materials of varying ages, and four large volcanic constructs. Scattered impact craters, small shields and pancake-shaped domes, and isolated flows superpose the tectonically deformed materials and appear to be the most youthful materials in the map region.

Scientific Investigations Map↗