USGS Science⌕ Search

SEARCH · USGS Science

Results for “geologic map”

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

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 541 records · Page 30Linked to original sources
USGS1991

Quaternary geologic map of the Lake Erie 4 degrees x 6 degrees quadrangle, United States and Canada

The Quaternary Geologic Map of the Lake Erie 4? x 6? 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.

IMAP↗
USGS1984

Quaternary geologic map of the Lake Superior 4 degrees x 6 degrees quadrangle, United States and Canada

The Quaternary Geologic Map of the Lake Superior 4? x 6? 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.

IMAP↗
USGS2009

Geologic Map of the Atlin Quadrangle, Southeastern Alaska

This map presents the results of U.S. Geological Survey (USGS) geologic bedrock mapping studies in the mostly glacier covered Atlin 1:250,000-scale quadrangle, northern southeastern Alaska. These studies are part of a long-term systematic effort by the USGS to provide bedrock geologic and mineral-resource information for all of southeastern Alaska, covering all of the Tongass National Forest (including Wilderness Areas) and Glacier Bay National Park and Preserve. Some contributions to this effort are those concerned with southwesternmost part of the region, the Craig and Dixon Entrance quadrangles (Brew, 1994; 1996) and with the Wrangell-Petersburg area (Brew, 1997a-m; Brew and Grybeck, 1997; Brew and Koch, 1997). As shown on the index map (fig. 1), the study area is almost entirely in the northern Coast Mountains adjacent to British Columbia, Canada. No previous geologic map has been published for the area, although Brew and Ford (1985) included a small part of it in a preliminary compilation of the adjoining Juneau quadrangle; and Brew and others (1991a) showed the geology at 1:500,000 scale. Areas mapped nearby in British Columbia and the United States are also shown on figure 1. All of the map area is in the Coast Mountains Complex as defined by Brew and others (1995a). A comprehensive bibliography is available for this and adjacent areas (Brew, 1997n).

Scientific Investigations Map↗
USGS2010

Geologic map of the Sand Creek Pass quadrangle, Larimer County, Colorado, and Albany County, Wyoming

New geologic mapping within the Sand Creek Pass 7.5 minute quadrangle defines geologic relationships within the northern Front Range of Colorado along the Wyoming border approximately 35 km south of Laramie, Wyo. Previous mapping within the quadrangle was limited to regional reconnaissance mapping; Eaton Reservoir 7.5 minute quadrangle to the east (2008), granite of the Rawah batholith to the south (1983), Laramie River valley to the west (1979), and the Laramie 30' x 60' quadrangle to the north (2007). Fieldwork was completed during 1981 and 1982 and during 2007 and 2008. Mapping was compiled at 1:24,000-scale. Minimal petrographic work was done and no isotope work was done in the quadrangle area, but detailed petrographic and isotope studies were performed on correlative map units in surrounding areas as part of a related regional study of the northern Front Range. Stratigraphy of Proterozoic rocks is primarily based upon field observation of bulk mineral composition, macroscopic textural features, and field relationships that allow for correlation with rocks studied in greater detail outside of the map area. Stratigraphy of Phanerozoic rocks is primarily based upon correlation with similar rocks to the north in the Laramie Basin of Wyoming and to the east in the Front Range of Colorado.

Scientific Investigations Map↗
USGS2014

Digital data for preliminary geologic map of the Mount Hood 30- by 60-minute quadrangle, northern Cascade Range, Oregon

The Mount Hood 30- by 60-minute quadrangle covers the axis and east flank of the Cascade Range in northern Oregon. Its namesake, Mount Hood volcano, dominates the view in the northwest quarter of the quadrangle, but the entire area is underlain by Oligocene and younger volcanic and volcaniclastic rocks of the Cascade Range. Since the time of the Columbia River Basalt Group about 15 million years (m.y.) ago, the locus and composition of Cascade Range volcanism have shifted sporadically across the map area. Andesitic eruptions were predominant in the western part from about 14 to 10 m.y. ago (Salmon and Sandy Rivers area), producing the Rhododendron Formation and overlying lava flows. From about 8 to 6.5 m.y. ago, lithic pyroclastic debris of the Dalles Formation was shed by chiefly andesitic volcanoes in the north-central part of the map area (Hood River valley escarpment). Andesitic to dacitic volcanism was again predominant about 5 to 3 m.y. ago, with known eruptive centers located from Lookout Mountain westward to Lolo Pass, probably including the area now occupied by Mount Hood. A major episode of mafic volcanism-basalt and basaltic andesite-began about 3-4 m.y. ago and lasted until about 2 m.y. ago. Volcanism since about 2 m.y. ago has been concentrated along the axis of the High Cascades. North and south of Mount Hood these youngest rocks are predominantly basaltic andesite lava flows; whereas at Mount Hood itself, andesite is predominant, forming pyroclastic and debris-flow deposits and lava flows. This geodatabase contains information derived from legacy mapping that was published in 1995 as U.S. Geological Survey Open-File Report 95-219. The main component of this publication is a geologic map database prepared using geographic information system (GIS) applications. Included are pdf files to view or print the map sheet, the accompanying pamphlet from Open-File Report 95-219, and links to the original publication, which is available as scanned files in pdf format.

Oregon↗
USGS2003

Geologic map of the MTM 85080 Quadrangle, Chasma Boreale Region of Mars

The polar deposits on Mars probably record martian climate history over the last 107 to 109 years (for example, Thomas and others, 1992). The area shown on this map includes polar layered deposits and polar ice, as well as some outcrops of older, underlying terrain. This quadrangle was mapped using Viking Orbiter images in order to study the relations among erosional and depositional processes on the north polar layered deposits and to compare them with the results of previous 1:500,000-scale mapping of the south polar layered deposits. Published geologic maps of the north polar region of Mars are based on images acquired by Mariner 9 and the Viking Orbiters. The extent of the layered deposits and other units varies among previous maps, in particular within Chasma Boreale. The present map agrees most closely with the map by Dial and Dohm (1994): the mantle material is exposed farther north than mapped by Tanaka and Scott (1987). The polar ice cap, areas of partial frost cover, the layered deposits, and two nonvolatile surface units-dust mantle and dark material-were mapped in the south polar region by Herkenhoff and Murray (1990a) at 1:2,000,000 scale using a color mosaic of Viking Orbiter images. Viking Orbiter rev 726, 768, and 771 color mosaics (taken during the northern summer of 1978) were constructed and used to identify similar color/albedo units in the north polar region, including the dark, saltating material that appears to have sources within the layered deposits. However, no dark material has been recognized in this map area. No significant difference in color exists between the layered deposits and the mantle material mapped by Dial and Dohm (1994), indicating that they are either composed of the same materials or are both covered by eolian debris. Therefore, in this map area the color mosaics are most useful for identifying areas of partial frost cover. Because the resolution of the color mosaics is not sufficient to map the color/albedo units in detail at 1:500,000-scale, contacts between them were recognized and mapped using higher resolution black-and-white Viking Orbiter images. The Viking Orbiter 2 images used to construct the map base were taken during the northern summer of 1976 (mostly Ls=133?-135?), with resolutions typically around 60 m/pixel. As noted on the published base, errors of up to 5 km exist in the placement of images in the base map; such errors are evident upon comparison of sheet 1 (summer) and sheet 2 (spring). Therefore, a new photomosaic base was created during map production and the linework was edited to match the new base. No craters have been found in the north polar layered deposits or polar ice cap. The observed lack of craters larger than 300 m implies that the surfaces of these units are no more than 100,000 years old or that they have been resurfaced at a rate of at least 2.3 mm/yr. The recent cratering flux on Mars is poorly constrained, so inferred resurfacing rates and ages of surface units are uncertain by at least a factor of 2.

IMAP↗
USGS2001

Preliminary digital geologic map of the Appalachian Piedmont and Blue Ridge, South Carolina segment

A preliminary geology coverage of the Piedmont and Blue Ridge in South Carolina has been compiled at 1:5000,000 scale and digitized as part of a patchwork of coverages for the analysis of regional and national geochemical patterns that may have environmental and resource implications. It was produced from other compilations that incorporate more detailed geologic maps as well as additional sources. The compilation is designed to meet short-term needs until better coverage of the regional geology is available.

Open-File Report↗
USGS2007

Quantitative analysis of scale of aeromagnetic data raises questions about geologic-map scale

A recently published study has shown that small-scale geologic map data can reproduce mineral assessments made with considerably larger scale data. This result contradicts conventional wisdom about the importance of scale in mineral exploration, at least for regional studies. In order to formally investigate aspects of scale, a weights-of-evidence analysis using known gold occurrences and deposits in the Central Lapland Greenstone Belt of Finland as training sites provided a test of the predictive power of the aeromagnetic data. These orogenic-mesothermal-type gold occurrences and deposits have strong lithologic and structural controls associated with long (up to several kilometers), narrow (up to hundreds of meters) hydrothermal alteration zones with associated magnetic lows. The aeromagnetic data were processed using conventional geophysical methods of successive upward continuation simulating terrane clearance or 'flight height' from the original 30 m to an artificial 2000 m. The analyses show, as expected, that the predictive power of aeromagnetic data, as measured by the weights-of-evidence contrast, decreases with increasing flight height. Interestingly, the Moran autocorrelation of aeromagnetic data representing differing flight height, that is spatial scales, decreases with decreasing resolution of source data. The Moran autocorrelation coefficient scems to be another measure of the quality of the aeromagnetic data for predicting exploration targets. ?? Springer Science+Business Media, LLC 2007.

Natural Resources Research↗
USGS1992

Geologic map of the MTM 90000 area, Planum Australe region of Mars

Published geologic maps of the south polar region of Mars, made using either Mariner 9 ( Condit and Soderbloom , 1978) or Viking Orbiter (Tanaka and Scott, 1987) images, identified only layered deposits of polar ice within this map area. Layered deposits probably underlie all of the other units shown in the map. The residual polar ice cap, partial frost cover, and two low-albedo units are also mapped here. These u nits were first recognized and mapped by Herkenhoff and Murray (1990a) at 1:2,000,000 scale using a color mosaic of Viking Orbiter images. This mosaic and an additional Viking color mosaic were used to confirm the identification of the five mapped color/albedo units. The colors and albedos of these units were presented in table 1 and figure 1. Because the resolution of the color mosaics is not sufficient to map these units in details at 1:500,000 scale, contacts between them were recognized and mapped using higher resolution black and white Viking and Mariner 9 images .

IMAP↗
USGS1999

Digital geologic map of Yellowstone National Park, Idaho, Montana, and Wyoming and vicinity

The geology coverage was developed from the 1972 USGS Geologic Map of Yellowstone National Park. It contains polygons of bedrock formations, dikes, and faults. Errors in the 1972 map were corrected and an area outside the Park boundary on the west and south was added. Attributes attached to each polygon include a formation code, formation name, formation age, and a generalized unit name. Line attributes include water, contacts, and faults. Updated information includes a break down of Tertiary, and Quaternary volcanic rock units.

Idaho, Montana, Wyoming↗
USGS2024

Geologic map of Scoggins Dam, Henry Hagg Lake, and Scoggins Valley, Washington County, Oregon

New geologic mapping (Wells and others, 2020b) and geophysical mapping (Blakely and others, 2000; McPhee and others, 2014; Wells and others, 2020a) document kilometers of Cenozoic right-lateral offset along the Gales Creek Fault Zone, a major, northwest-striking fault zone forming the boundary between the Tualatin Valley and the Coast Range. The Bureau of Reclamation’s (Reclamation) Scoggins Dam (fig. 1), in the Coast Range foothills west of Forest Grove, Oregon, lies within the Gales Creek Fault Zone as mapped by Wells and others (2020a, 2020b; fig. 2). Active faults of the Gales Creek Fault Zone defined by paleoseismic trenching (Redwine and others, 2017, 2019b, Horst and others, 2018, 2019, 2021, and Wells and others, 2020a) are presently mapped as projecting through the existing dam. The Pacific Northwest Region of Reclamation requested assistance with geologic studies around Scoggins Dam to provide better understanding of fault locations and their activity, which are needed to design a modification of the dam (Maguire, 2019a, b). The scope of this project includes detailed geology of the existing Scoggins Dam site, Henry Hagg Lake, the reservoir behind the dam, and Scoggins Valley downstream of the existing dam, particularly around a potential new dam site, where Scoggins Creek cuts through a narrow gap formed by a resistant felsic tuff bed that crosses the valley.

Oregon↗
USGS2025

The USGS National Geologic Map Database – Resource for geoscience professionals and the public

Since 1996, the US Geological Survey (USGS) National Geologic Map Database (NGMDB) has served the public and private sectors and is widely recognized as one of the few authoritative resources for the information published by the nation’s geological surveys. On a monthly basis, the NGMDB website receives more than 600,000 visits by about 200,000 users (~20,000 visits per day). In a typical month, between 2 and 3 TB of content are viewed or downloaded. This high level of web traffic results in many user requests for information and assistance. Users vary widely in interest and background and include homeowners, students, local government planners, and professional geologists and engineers. Many professionals use NGMDB information for understanding natural conditions that affect infrastructure, such as drainage, ground stability, properties of near-surface earth materials, and depth to rock.

Conference Paper↗
USGS1945

Topographic and geologic maps of manganese deposits in California

Geologic and topographic maps of several manganese properties in California were released today by the Geological Survey according to an announcement made by Survey Director W. E. Wrather to Secretary of the Interior Harold L. Ickes. The maps have been placed on open file at the offices of the Geological Survey in Washington, D. C., and at the offices of the Geologic Branch, California Division of Mines, Ferry Building, San Francisco, where they may be consulted by persons directly interested in the properties. The recently increased demand for information regarding deposits of manganese silicates for new uses in connection with the war effort has indicated the desirability of releasing unpublished detailed maps of the California deposits, many of which carry manganese silicates. The maps were made as part of the strategic minerals investigations of the Geological Survey from 1941 to 1943. The deposits covered by the maps are in the following counties of California: Amador, Calaveras, Eldorado, Glenn, Humboldt, Los Angeles, Madera, Mariposa, Mendocino, Mono, Placer, Plumas, San Bernardino, San Benito, San Luis Obispo, San Joaquin, Sonoma, Stanislaus, Trinity, and Tuolumne.

California↗
USGS1999

Geologic map of the Seldovia quadrangle, south-central Alaska

This is a 1:250,000-scale map of the bedrock geology of the Seldovia quadrangle, south-central Alaska. The map area covers the southwestern end of the Kenai Peninsula, including the Kenai Lowlands and Kenai Mountains, on either side of Kachemak Bay. The waters of Cook Inlet cover roughly half of the map area, and a part of the Alaska Peninsula near Iliamna Volcano lies in the extreme northwest corner of the map. The bedrock geology is based on new reconnaissance field work by the U.S. Geological Survey during parts of the 1988-1993 field seasons, and on previous mapping from a number of sources. The new mapping focused on the previously little-known Chugach accretionary complex in the Kenai Mountains. Important new findings include the recognition of mappable subdivisions of the McHugh Complex (a subduction melange of mostly Mesozoic protoliths), more accurate placement of the thrust contact between the McHugh Complex and Valdez Group (Upper Cretaceous trench turbidites), and the recognition of several new near-trench plutons of early Tertiary age.

Open-File Report↗
USGS2020

Preliminary bedrock geologic map of the Lahore 7.5-minute quadrangle, Orange, Spotsylvania, and Louisa Counties, Virginia

Introduction Bedrock geologic mapping of the Lahore, Va., 7.5-minute quadrangle was completed as part of a broader project, undertaken jointly between the U.S. Geological Survey, the Virginia Division of Geology and Mineral Resources, and other Federal and State agencies to better understand the causative mechanisms of the magnitude-5.8 (M5.8) earthquake that occurred near Mineral, Va., on August 23, 2011. This project involved detailed mapping of eight quadrangles in the epicentral region of the Mineral, Va., earthquake in order to improve our understanding of the geologic framework of the central Virginia seismic zone, which has a long record of historical and prehistoric seismicity. The Lahore 7.5-minute quadrangle contains the contact between Ordovician to Silurian, dioritic and granodioritic rocks of the Lahore and Ellisville plutons and older metasedimentary and metavolcanic rocks. The Lahore quadrangle is northeast of the Ferncliff and Louisa, Va., quadrangles, where the Shores complex is intruded by the Ellisville pluton along the pluton’s southwestern margin. The new mapping in the Lahore quadrangle shows that the Shores complex continues northeast of the Ellisville pluton. A northeast-trending mafic- and ultramafic-bearing belt within the Shores complex is a fault-bounded accretionary zone (accretionary wedge) between rocks of the Chopawamsic Formation and Laurentian slope-and-rise deposits. In the Lahore quadrangle, this belt contains several mappable, northeast- to southwest-trending mafic bodies and also includes small exposures of gabbro and talc schist. The Lahore quadrangle contains structures of both early- and late-Paleozoic age that correspond to the Taconic and Alleghanian orogenies. Taconic (Late Ordovician) S 1 schistosity in layered rocks is typically fine-grained and parallel to compositional layering, when present. Alleghanian (Pennsylvanian) S 2 schistosity is coarser and more micaceous than S 1 and is locally accompanied by a lineation that is represented by mineral lineations, micro-crenulations, or mullion fabric, and represents the hinges of F 2 folds. A foliation in the plutonic rocks is represented by an equilibrium assemblage of aligned mafic minerals and is early Paleozoic in age. Metamorphic grade in the non-plutonic rocks of the Lahore quadrangle ranges from lower-greenschist to the northwest to upper-greenschist to the southeast, as represented by mineral assemblages in non-plutonic rocks. The biotite isograd may be, in part, lithologically controlled by the contact between the informally-named Hardware and Byrd Mill formations, and locally affected by contact metamorphism by the Lahore pluton (western part of map). The Taconic garnet isograd is defined by the sparse presence of small (less than 1 millimeter), euhedral garnet crystals. Both the biotite and garnet isograds continue along strike to the southwest into the Ferncliff and Louisa quadrangles, where the isograds have been identified as Ordovician age (Taconic orogeny) based on muscovite, biotite, and amphibole 40 Ar/ 39 Ar cooling ages. Regionally, the most common trend and plunge of joints is northwest and subvertical, respectively, and orthogonal to the regional strike of foliation. Early Mesozoic extension may have reactivated the Harris Creek fault (southeast corner of map), a late Paleozoic (Alleghanian orogeny) transpressional fault that marks the contact between granodiorite of the Ellisville pluton and the Chopawamsic Formation.

Virginia↗
USGS2022

Geologic map of the South Boston 30' × 60' quadrangle, Virginia and North Carolina

This 1:100,000-scale geologic map of the South Boston 30 ’ × 60 ’ quadrangle, Virginia and North Carolina, provides geologic information for the Piedmont along the I–85 and U.S. Route 58 corridors and in the Roanoke River watershed, which includes the John H. Kerr Reservoir and Lake Gaston. The Raleigh terrane (located on the eastern side of the map) contains Neoproterozoic to early Paleozoic(?) polydeformed, amphibolite-facies gneisses and schists. The Carolina slate belt of the Carolina terrane (located in the central part of the map) contains Neoproterozoic metavolcanic and metasedimentary rocks at greenschist facies. Although locally complicated, the slate-belt structure mapped across the South Boston map area is generally a broad, complex anticlinorium of the Hyco Formation (here called the Chase City anticlinorium) and is flanked to the west and east by synclinoria, which are cored by the overlying Aaron and Virgilina Formations. The western flank of the Carolina terrane (located in the western-central part of the map) contains similar rocks at higher metamorphic grade. This terrane includes epidote-amphibolite-facies to amphibolite-facies gneisses of the Neoproterozoic Country Line complex, which extends north-northeastward across the map. The Milton terrane (located on the western side of the map) contains Ordovician amphibolite-facies metavolcanic and metasedimentary gneisses of the Cunningham complex. Crosscutting relations and fabrics in mafic to felsic plutonic rocks constrain the timing of Neoproterozoic to late Paleozoic deformations across the Piedmont. In the eastern part of the map, a 5- to 9-kilometer-wide band of tectonic elements that contains two late Paleozoic mylonite zones (Nutbush Creek and Lake Gordon) and syntectonic granite (Buggs Island pluton) separates the Raleigh and Carolina terranes. Amphibolite-facies, infrastructural metaigneous and metasedimentary rocks east of the Lake Gordon mylonite zone are generally assigned to the Raleigh terrane. In the western part of the map area, a 5- to 8-kilometer-wide band of late Paleozoic tectonic elements includes the Hyco and Clover shear zones, syntectonic granitic sheets, and amphibolite-facies gneisses along the western margin of the Carolina terrane at its boundary with the Milton terrane. This band of tectonic elements is also the locus for early Mesozoic extensional faults associated with the early Mesozoic Scottsburg, Randolph, and Roanoke Creek rift basins. The map shows fluvial terrace deposits of sand and gravel on hills and slopes near the Roanoke and Dan Rivers. The terrace deposits that are highest in altitude are the oldest. Saprolite regolith is spatially associated with geologic source units and is not shown separately on the map. Mineral resources in the area include gneiss and granite quarried for crushed stone, tungsten-bearing vein deposits of the Hamme district, and copper and gold deposits of the Virgilina district. Surface-water resources are abundant and include rivers, tributaries, the John H. Kerr Reservoir, and Lake Gaston. Groundwater flow is concentrated in saprolite regolith, along fractures in the crystalline bedrock, and along fractures and bedding-plane partings in the Mesozoic rift basins.

North Carolina, Virginia↗