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At least 721 records · Page 40Linked to original sources
USGS1986

Quaternary geologic map of the Florida Keys 4° x 6° 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 1986. 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 Florida Keys 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. 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.

Florida↗
USGS1993

Quaternary geologic map of the Austin 4° x 6° 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 Austin 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. 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.

Texas↗
USGS1990

Quaternary geologic map of the White Lake 4° x 6° 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 1990. 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 White Lake 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. 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.

Louisiana, Texas↗
USGS1988

Quaternary geologic map of the Mobile 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 1988. 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 Mobile 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

IMAP↗
USGS1986

Quaternary geologic map of the Jacksonville 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 1986. 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 Jacksonville 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↗
USGS1990

Quaternary geologic map of the Vicksburg 4° x 6° 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 1990. 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 Vicksburg 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. 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.

Arkansas, Louisiana, Mississippi, Oklahoma, Tennes↗
USGS1988

Quaternary geologic map of the Lookout Mountain 4° x 6° 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 1988. 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 Lookout Mountain 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. 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.

Alabama, Arkansas, Georgia, Mississippi, North Car↗
USGS1993

Quaternary geologic map of the Wichita 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 Wichita 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. 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↗
USGS1989

Geologic Map of the San Luis Hills Area, Conejos and Costilla Counties, Colorado

This report is a digital image of the U.S. Geological Survey Miscellaneous Investigations Series Map I-1906, 'Geologic map of the San Luis Hills area, Conejos and Costilla Counties, Colorado,' which was published in 1989 by Thompson and Machette, scale 1:50,000 but has been unavailable in a digital version. The map area represents the southwestern portion of the Alamosa 30' x 60' quadrangle, which is currently being remapped by the U.S. Geological Survey. The northern and eastern margins of the San Luis Hills area have been remapped at greater detail and thus small portions of the map area have been updated. The northern margin is shown on U.S. Geological Survey Open-File Report 2005-1392, the northeastern portion is shown on U.S. Geological Survey Open-File Report 2008-1124, and the eastern margin is shown on U.S. Geological Survey Open-File Report 2007-1074. The most significant changes to the 1989 map area are recognition of Lake Alamosa and its deposits (Alamosa Formation), remapping of bedrock in the northeastern San Luis Hills, and redating of volcanic units in the San Luis Hills. Although unpublished, new 40Ar/39Ar ages for volcanic units in the Conejos and Hinsdale Formations add precision to the previous K/Ar-dated rocks, but do not change the basic chronology of the units. The digital version of this map was prepared by Theodore R. Brandt by scanning the original map at 300 pixels per inch, prior to creating the press-quality (96 Mb) and standard (5 Mb) .pdf files.

IMAP↗
USGS1993

Geologic map of the Palo Alto and part of the Redwood Point 7-1/2' quadrangles, San Mateo and Santa Clara Counties, California

The Palo Alto and southern part of the Redwood Point 7-1/2' quadrangles cover an area on the San Francisco peninsula between San Francisco Bay and the Santa Cruz Mountains. San Francisquito and Los Trancos Creeks, in the southeastern part of the map area, form the boundary between San Mateo and Santa Clara Counties. The area covered by the geologic map extends from tidal and marsh lands at the edge of the bay southward across a gently sloping alluvial plain to the foothills of the northern Santa Cruz Mountains. The foothills are separated from the main mass of the mountains by two northwest-striking faults, the San Andreas and Pilarcitos, that cross the southwest corner of the map area (fig. 1). The map and adjoining areas are here divided into three structural blocks juxtaposed along these faults, adopting the scheme of Nilsen and Brabb (1979): (1) the San Francisco Bay block lying east of the San Andreas Fault Zone; (2) the Pilarcitos block lying between the San Andreas and Pilarcitos Faults; and (3) the La Honda block that includes the main mass of the Santa Cruz Mountains lying west of the Pilarcitos Fault. The west boundary of the La Honda block is the Seal Cove-San Gregorio Fault. Pre-late Pleistocene Cenozoic rocks of the foothills have been compressed into northwest-striking folds, which have been overridden by Mesozoic rocks along southwest-dipping low-angle faults. Coarse- to fine-grained upper Pleistocene and Holocene alluvial and estuarine deposits, eroded from the foothills and composing the alluvial plain, are essentially undeformed. Most of the alluvial plain, including some parts of the marsh land that borders the bay, has been covered by residential and commercial developments, and virtually all of the remaining marsh land has been diked off and used as salt evaporating ponds. The map area includes parts of the municipalities of San Carlos, Redwood City, Atherton, Woodside, Portola Valley, Menlo Park, and East Palo Alto in San Mateo County; and Palo Alto, Stanford University, Los Altos, and Los Altos Hills in Santa Clara County (fig. 2). Much of the university land remains as undeveloped open space surrounded by densely urbanized lands. Geologic maps of all or part of the present map area have been prepared previously by Branner and others (1909), Thomas (1949), Dobbs and Forbes (1960), Dibblee (1966), Page and Tabor (1967), Pampeyan (1970a, 1970b), Beaulieu (1970), Helley and others (1979), and by numerous Stanford University students working on topical earth science problems. In addition, numerous engineering geologic studies have been conducted for site investigations relating to residential and commercial developments and, in particular, for construction of the Stanford Linear Accelerator Center (SLAC). The reports pertaining to SLAC are summarized in Skjei and others (1965) and more recently in a report by Earth Sciences Associates (1983). The interested reader is referred to Brabb and Pampeyan (1983), Brabb and others (1982), Wentworth and others (1985), Wieczorek and others (1985), Thomson and Evernden (1986), Brabb and Olson (1986), Youd and Perkins (1987), Perkins (1987), and Mark and Newman (1988) for information pertaining to geology, history, slope stability, seismic shaking, liquifaction potential, and faulting and seismicity in San Mateo County, some of which can be applied directly to northern Santa Clara County. Field work for the present geologic map was done in 1962-1964 and 1966 when SLAC and Interstate 280 were in early stages of construction. Only minor additions and revisions have been made since this mapping was first released (Pampeyan, 1970a; 1970b) as it was impractical to keep pace with accelerating urban development of the area. Geologic units of the flatlands area are largely adapted from Helley and Lajoie (1979).

California↗
USGS2003

Geologic map of the Big Delta B-2 quadrangle, east-central Alaska

New 1:63,360-scale geologic mapping of the Big Delta B-2 quadrangle provides important data on the structural setting and age of geologic units, as well as on the timing of gold mineralization plutonism within the Yukon-Tanana Upland of east-central Alaska. Gold exploration has remained active throughout the region in response to the discovery of the Pogo gold deposit, which lies within the northwestern part of the quadrangle near the south bank of the Goodpaster River. Geologic mapping and associated geochronological and geochemical studies by the U.S. Geological Survey (USGS) and the Alaska Department of Natural Resources, Division of Mining and Water Management, provide baseline data to help understand the regional geologic framework. Teck Cominco Limited geologists have provided the geologic mapping for the area that overlies the Pogo gold deposit as well as logistical support, which has lead to a much improved and informative product. The Yukon-Tanana Upland lies within the Tintina province in Alaska and consists of Paleozoic and possibly older(?) supracrustal rocks intruded by Paleozoic (Devonian to Mississippian) and Cretaceous plutons. The oldest rocks in the Big Delta B-2 quadrangle are Paleozoic gneisses of both plutonic and sedimentary origin. Paleozoic deformation, potentially associated with plutonism, was obscured by intense Mesozoic deformation and metamorphism. At least some of the rocks in the quadrangle underwent tectonism during the Middle Jurassic (about 188 Ma), and were subsequently deformed in an Early Cretaceous contractional event between about 130 and 116 Ma. New U-Pb SHRIMP data presented here on zircons from the Paleozoic biotite gneisses record inherited cores that range from 363 Ma to about 2,130 Ma and have rims of euhedral Early Cretaceous metamorphic overgrowths (116 +/- 4 Ma), interpreted to record recrystallization during Cretaceous west-northwest-directed thrusting and folding. U-Pb SHRIMP dating of monazite from a Paleozoic gneiss sample yields an age of 112 +/- 2 Ma; the monazite presumably grew during the waning stages of the intense regional Cretaceous ductile deformation. The Cretaceous ductile deformation was followed closely by granite plutonism and gold mineralization. The main pulse of gold mineralization is temporally and spatially associated with the Cretaceous granitic dikes and plutons and occurred during regional uplift and extension.

IMAP↗
USGS1961

Geology of the Huntsville quadrangle, Alabama

The 7 1/2-minute Huntsville quadrangle is in south-central Madison County, Ala., and includes part of the city of Hunstville. The south, north, east, and west boundaries of the quadrangle are about 3 miles north of the Tennessee River, 15 1/2 miles south of the Tennessee line, 8 miles west of the Jackson County line, and 9 miles east of the Limestone County line. The bedrock geology of the Huntsville quadrangle was mapped by the U.S. Geological Survey in cooperation with the city of Hunstville and the Geological Survey of Alabama as part of a detailed study of the geology and ground-water resources of Madison County, with special reference to the Huntsville area. G. T. Malmberg began the geologic mapping of the county in July 1953, and completed it in April 1954. T. H. Sanford, Jr., assisted Malmberg in the final phases of the county mapping, which included measuring geologic sections with hand level and steel tape. In November 1958 Sanford, assisted by L. R. West, checked contacts and elevations in the Hunstville quadrangle; made revisions in the contact lines; and wrote the text for this report. The fieldwork for this report was completed in April 1959.

Alabama↗
USGS1961

Geology of the Moses Lake North quadrangle, Washington

The geology of the Moses Lake North quadrangle was mapped in 1954 and 1958 by the U.S. Geological Survey. Some of the basic hydrologic data has been collected by the Geological Survey during the early investigations of ground-water conditions in the Quincy Basin (Henshaw, written communication, 1917; Schwennesen and Meinzer, 1918). Most of the data, however, were obtained by the Geological Survey since 1941, in cooperation with the U.S. Bureau of Reclamation and the Washington State Department of Conservation under continuing programs in the area of the Columbia Basin Project of the Bureau of Reclamation. Some preliminary geologic field work in the Moses Lake North quadrangle was done by the Geological Survey in 1954 in cooperation with the Washington State Department of Conservation.

Washington↗
USGS2000

Geologic map of the upper Parashant Canyon and vicinity Mohave County, northwestern Arizona

The geologic map of the upper Parashant Canyon area covers part of the Colorado Plateau and several large tributary canyons that make up the western part of Arizona's Grand Canyon. The map is part of a cooperative U.S. Geological Survey and National Park Service project to provide geologic information for areas within the newly established Grand Canyon/Parashant Canyon National Monument. Most of the Grand Canyon and parts of the adjacent plateaus have been geologically mapped; this map fills in one of the remaining areas where uniform quality geologic mapping was needed. The geologic information presented may be useful in future related studies as to land use management, range management, and flood control programs for federal and state agencies, and private concerns. The map area is in a remote region of the Arizona Strip, northwestern Arizona about 88 km south of the nearest settlement of St. George, Utah. Elevations range from about 1,097 m (3,600 ft) in Parashant Canyon (south edge of map area) to 2,145 m (7,037 ft) near the east-central edge of the map area. Primary vehicle access is by dirt road locally known as the Mount Trumbull road; unimproved dirt roads and jeep trails traverse various parts of the map area. Travel on the Mount Trumbull road is possible with 2-wheel-drive vehicles except during wet conditions. Extra fuel, two spare tires and extra food and water are highly recommended when traveling in this remote area. The map area includes about 26 sections of land belonging to the State of Arizona, about 40 sections of private land, and a small strip of the Lake Mead National Recreation Area (southeast edge of the map area). The private land is mainly clustered around the abandoned settlement of Mt. Trumbull, locally known as Bundyville, and a few sections are scattered in the upper Whitmore Canyon area just south of Bundyville. Lower elevations within the canyons support a sparse growth of sagebrush, cactus, grass, creosote bush, and a variety of desert shrubs. Sagebrush, grass, cactus, cliffrose bush, pinyon pine trees, juniper trees, and some ponderosa pines thrive at higher elevations. Surface runoff in the north half of the map area drains northward towards the Virgin River in Utah via Hurricane Wash. In the south half of the area, it drains towards the Colorado River in Grand Canyon via Parashant and Whitmore Canyons. Upper Parashant and Whitmore Canyons are part of the physiography of the western Grand Canyon, but are not included within Grand Canyon National Park. The entire map area is now within the newly established Grand Canyon/Parashant Canyon National Monument (as of January, 2000), and is jointly managed by the Lake Mead National Recreational Area, Boulder City, Nevada, and the Bureau of Land Management, Arizona Strip District, St. George, Utah. Surface runoff in the north half of the map area drains northward towards the Virgin River in Utah via Hurricane Wash. In the south half of the area, it drains towards the Colorado River in Grand Canyon via Parashant and Whitmore Canyons. Upper Parashant and Whitmore Canyons are part of the physiography of the western Grand Canyon, but are not included within Grand Canyon National Park. The entire map area is now within the newly established Grand Canyon/Parashant Canyon National Monument (January, 2000), and is jointly managed by the Lake Mead National Recreational Area, Boulder City, Nevada, and the Bureau of Land Management, Arizona Strip District, St. George, Utah.

Arizona↗
USGS2002

Geologic map of the Tetilla Peak Quadrangle, Santa Fe and Sandoval counties, New Mexico

This digital geologic map summarizes all available geologic information for the Tetilla Peak quadrangle located immediately southwest of Santa Fe, New Mexico. The geologic map consists of new polygon (geologic map units) and line (contact, fault, fold axis, dike, flow contact, hachure) data, as well as point data (locations for structural measurements, geochemical and geochronologic data, geophysical soundings, and water wells). The map database has been generated at 1:24,000 scale, and provides significant new geologic information for an area of the southern Cerros del Rio volcanic field, which sits astride the boundary of the Espanola and Santo Domingo basins of the Rio Grande rift. The quadrangle includes the west part of the village of La Cienega along its eastern border and includes the southeasternmost part of the Cochiti Pueblo reservation along its northwest side. The central part of the quadrangle consists of Santa Fe National Forest and Bureau of Land Management lands, and parts of several Spanish-era land grants. Interstate 25 cuts through the southern half of the quadrangle between Santa Fe and Santo Domingo Pueblo. Canada de Santa Fe, a major river tributary to the Rio Grande, cuts through the quadrangle, but there is no dirt or paved road along the canyon bottom. A small abandoned uranium mine (the La Bajada mine) is found in the bottom of the Canada de Santa Fe about 3 km east of the La Bajada fault zone; it has been partially reclaimed. The surface geology of the Tetilla Peak quadrangle consists predominantly of a thin (1-2 m generally, locally as thick as 10? m) layer of windblown surficial deposits that has been reworked colluvially. Locally, landslide, fluvial, and pediment deposits are also important. These colluvial deposits mantle the principal bedrocks units, which are (from most to least common): (1) basalts, basanites, andesite, and trachyte of the Pliocene (2.7-2.2 Ma) Cerros del Rio volcanic field; (2) unconsolidated deposits of the Santa Fe Group, mainly along the western border, in the hanging wall of the La Bajada fault zone, but locally extending 2-3 km east under the Cerros del Rio volcanic field; (3) older Tertiary volcanic and sedimentary rocks (Abiquiu?, Espinaso, and Galisteo Formations); (4) intrusive rocks of the Cerrillos intrusive center that are roughly coeval with the Espinaso volcanic rocks; and (5) Mesozoic sedimentary rocks ranging in age from the Upper Triassic Chinle Formation to the Upper Cretaceous Mancos Shale.

New Mexico↗
USGS2001

Geologic Map of Part of the Uinkaret Volcanic Field, Mohave County, Northwestern Arizona

The geologic map of part of the Uinkaret Volcanic Field is one product of a cooperative project between the U.S. Geological Survey, the National Park Service, and the Bureau of Land Management to provide geologic information about this part of the Grand Canyon-Parashant Canyon National Monument of Arizona. The Uinkaret Volcanic Field is a unique part of western Grand Canyon where volcanic rocks have preserved the geomorphic development of the landscape. Most of the Grand Canyon, and parts of adjacent plateaus have already been mapped. This map completes one of the remaining areas where uniform quality geologic mapping was needed. A few dozen volcanoes and lava flows within the Grand Canyon are not included in the map area, but their geologic significance to Grand Canyon development is documented by Hamblin (1994) and mapped by Billingsley and Huntoon (1983) and Wenrich and others (1997). The geologic information in this report may be useful to resource managers of the Bureau of Land Management for range management, biological, archaeological, and flood control programs. The map area lies within the Shivwits, Uinkaret, and Kanab Plateaus, which are subplateaus of the Colorado Plateaus physiographic province (Billingsley and others, 1997), and is part of the Arizona Strip north of the Colorado River. The nearest settlement is Colorado City, Arizona, about 58 km (36 mi) north of the map area (fig. 1). Elevations range from about 2,447 m (8,029 ft) at Mount Trumbull, in the northwest quarter of the map area, to about 732 m (2,400 ft) in Cove Canyon, in the southeast quarter of the map area. Vehicle access is via the Toroweap and Mount Trumbull dirt roads (fig. 1). Unimproved dirt roads traverse other parts of the area except in designated wilderness. Extra fuel, two spare tires, and extra food and water are highly recommended for travelers in this remote area. The U.S. Bureau of Land Management, Arizona Strip Field Office, St. George, Utah manages most of the area. In addition, there are 12 sections belonging to the State of Arizona, about 12 sections are private land, and several sections are within the Grand Canyon National Park and Lake Mead National Recreational Area (U.S. Department of the Interior, 1993). The private land is in Potato Valley and Lake Valley, southwest and west of Mount Trumbull, and in Whitmore Canyon and Toroweap (Tuweap) Valley. Portions of the Sawmill Mountains, Mount Logan, and Mount Trumbull areas were originally established as part of the Dixie National Forest in 1904. In 1924, Dixie National Forest land became part of the Kaibab National Forest. Then on February 13, 1974, management of this part of the Kaibab National Forest was transferred to the Bureau of Land Management, Arizona Strip Field Office (personal commun. Becky Hammond, Bureau of Land Management, 1997). Mount Logan and part of the Sawmill Mountains are now designated as the Mount Logan Wilderness Area, and Mount Trumbull is designated as the Mount Trumbull Wilderness Area. Most of the map area is now part of the new Grand Canyon-Parashant Canyon National Monument established January 11, 2000. Lower elevations within Hells Hollow, Whitmore Canyon, Toroweap Valley, and Cove Canyon support a sparse growth of sagebrush, cactus, grass, and a variety of desert shrubs. Sagebrush, grass, cactus, cliffrose bush, pinion pine, and juniper trees thrive at elevations above 1,830 m (6,000 ft). Ponderosa pine and oak forests thrive at higher elevations in the Mount Trumbull and Mount Logan areas. Surface runoff within the map area drains south towards the Colorado River through Hells Hole, Hollow, Whitmore Canyon, Toroweap Valley, and Cove Canyon. Upper Toroweap Valley, upper Hells Hollow, and Whitmore Canyon are part of the physiographic area of Grand Canyon, but are not within Grand Canyon National Park (Billingsley and others, 1997). As of January 11, 2000, these areas are now part of the new Grand Canyon-Parashant

Miscellaneous Field Studies Map↗
USGS2001

Interpretive geologic cross sections for the Death Valley regional flow system and surrounding areas, Nevada and California

This report presents a network of 28 geologic cross sections that portray subsurface geologic relations within the Death Valley regional ground-water system, a ground-water basin that encompasses a 3? x 3? area (approximately 70,000 km2) in southern Nevada and eastern California. The cross sections transect that part of the southern Great Basin that includes Death Valley, the Nevada Test Site, and the potential high-level nuclear waste underground repository at Yucca Mountain. The specific geometric relationships portrayed on the cross sections are discussed in the context of four general sub-regions that have stratigraphic similarities and general consistency of structural style: (1) the Nevada Test Site vicinity; (2) the Spring Mountains, Pahrump Valley and Amargosa Desert region; (3) the Death Valley region; and (4) the area east of the Nevada Test Site. The subsurface geologic interpretations portrayed on the cross sections are based on an integration of existing geologic maps, measured stratigraphic sections, published cross sections, well data, and geophysical data and interpretations. The estimated top of pre-Cenozoic rocks in the cross sections is based on inversion of gravity data, but the deeper parts of the sections are based on geologic conceptual models and are more speculative. The region transected by the cross sections includes part of the southern Basin and Range Province, the northwest-trending Walker Lane belt, the Death Valley region, and the northern Mojave Desert. The region is structurally complex, where a locally thick Tertiary volcanic and sedimentary section unconformably overlies previously deformed Proterozoic through Paleozoic rocks. All of these rocks have been deformed by complex Neogene ex-tensional normal and strike-slip faults. These cross sections form a three-dimensional network that portrays the interpreted stratigraphic and structural relations in the region; the sections form part of the geologic framework that will be incorporated in a complex numerical model of ground-water flow in the Death Valley region.

California, Nevada↗
USGS2000

Geologic map and digital database of the Cougar Buttes 7.5' quadrangle, San Bernardino County, California

The Southern California Areal Mapping Project (SCAMP) of Geologic Division has undertaken regional geologic mapping investigations in the Lucerne Valley area co-sponsored by the Mojave Water Agency and the San Bernardino National Forest. These investigations span the Lucerne Valley basin from the San Bernardino Mountains front northward to the basin axis on the Mojave Desert floor, and from the Rabbit Lake basin east to the Old Woman Springs area. Quadrangles mapped include the Cougar Buttes 7.5' quadrangle, the Lucerne Valley 7.5' quadrangle (Matti and others, in preparation b), the Fawnskin 7.5' quadrangle (Miller and others, 1998), and the Big Bear City 7.5' quadrangle (Matti and others, in preparation a). The Cougar Buttes quadrangle has been mapped previously at scales of 1:62,500 (Dibblee, 1964) and 1:24,000 (Shreve, 1958, 1968; Sadler, 1982a). In line with the goals of the National Cooperative Geologic Mapping Program (NCGMP), our mapping of the Cougar Buttes quadrangle has been directed toward generating a multipurpose digital geologic map database. Guided by the mapping of previous investigators, we have focused on improving our understanding and representation of late Pliocene and Quaternary deposits. In cooperation with the Water Resources Division of the U.S. Geological Survey, we have used our mapping in the Cougar Buttes and Lucerne Valley quadrangles together with well log data to construct cross-sections of the Lucerne Valley basin (R.E. Powell, unpublished data, 1996-1998) and to develop a hydrogeologic framework for the basin. Currently, our mapping in these two quadrangles also is being used as a base for studying soils on various Quaternary landscape surfaces on the San Bernardino piedmont (Eppes and others, 1998). In the Cougar Buttes quadrangle, we have endeavored to represent the surficial geology in a way that provides a base suitable for ecosystem assessment, an effort that has entailed differentiating surficial veneers on piedmont and pediment surfaces and distinguishing the various substrates found beneath these veneers.

California↗