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At least 523 records · Page 29Linked to original sources
USGS1969

Geologic Settings of Subsidence

This paper reviews the role of geologic processes that contribute to subsidence in order to aid those starting investigations of ground-surface subsidence. Subsidence occurs, or at least is discovered, only infrequently, and little organized information has been available. In order to assess our present state of knowledge, the author gathered fragmentary bits of information from many sources widely scattered in the literature of geology and other earth sciences. The author cites examples for each geologic process that is a potential contributor to ground-surface subsidence together with geologic evidence for diagnosing their causes. The geologic processes involved are: (1) solution of gypsum and salt and redistribution of transient fill materials through solution cavities in calcareous rocks; (2) underground erosion of uncemented or lightly cemented silt and sand through temporary underground passageways; (3) lateral plastic flow of salt, gypsum and anhydrite, shale, and clay under loading; (4) compaction of sediments by loading, drainage, vibration, and hydrocompaction; (5) tectonic movements including primary and secondary effects of earthquakes, folding, and warping; and (6) volcanic activity. Because the first four processes may be accelerated by various engineering activities, examples have been selected to illustrate subsidence both under natural conditions and under conditions modified by man's activities. Although this extensive search for existing information on the role of geologic factors in subsidence indicates that much detailed work remains to be done, the future prospects for advancing our geologic knowledge are excellent. Methods of measuring ground-surface displacements are improving rapidly. Also, broadly based investigations of known areas of major subsidence throughout the world are developing new methods of diagnosis and treatment and are yielding quantitative data that will aid our evaluation of the rates and magnitude of present-day geologic processes.

Book chapter↗
USGS2019

Three-dimensional geologic mapping to assess geothermal potential: Examples from Nevada and Oregon

Geologic structure plays an important role in controlling fluid flow in geothermal systems. In particular, very complex structural settings, consisting of many closely spaced and intersecting faults, host many geothermal systems. To elucidate the key geologic factors that affect fault-controlled geothermal circulation, it is critical to precisely characterize the structural and stratigraphic geometries in these complex settings. Here, we present a methodology and the results of 3D geologic analyses of two geothermal systems in the Basin and Range, USA. This methodology is a quantitative and geologically focused technique that can be used to precisely characterize geothermal areas, in a time when future geothermal growth demands increased exploration precision and efficiency. Surficial and subsurface geologic and geophysical data are synthesized in the construction of detailed 3D geologic maps of geothermal areas. Based on these 3D geologic maps, we examine several geologic attributes that control permeability development and geothermal fluid flow along faults. We use the stress state of faults and the distribution of structural discontinuities (i.e., fault intersections and fault terminations) to identify locations of upflow along faults in these geothermal systems. These results and the methodology presented herein are directly applicable to structurally controlled geothermal fields in the Basin and Range and worldwide. As development focus shifts toward blind geothermal resources, integration of precisely characterized subsurface structural information into exploration methods will be increasingly critical to continued growth in geothermal exploration and development.

Nevada, Oregon↗
USGS1969

The Geologic Story of the Uinta Mountains

The opening of the West after the Civil War greatly stimulated early geologic exploration west of the 100th Meridian. One of the areas first studied, the Uinta Mountains region, gained wide attention as a result of the explorations of three Territorial Surveys, one headed by John Wesley Powell, one by Clarence King, and one by Ferdinand V. Hayden. Completion of the Union Pacific Railroad across southern Wyoming 100 years ago, in 1869, materially assisted geologic exploration, and the railheads at Green River and Rock Springs greatly simplified the outfitting of expeditions into the mountains. The overlap of the Powell, King, and Hayden surveys in the Uinta Mountains led to efforts that were less concerted than competitive and not without acrimony. Many parts of the area were seen by all three parties at almost the same time. Duplication was inevitable, of course, but all three surveys contributed vast quantities of new knowledge to the storehouse of geology, and many now-basic concepts arose from their observations. Powell's area of interest extended mainly southward from the Uinta Mountains to the Grand Canyon, including the boundless plateaus and canyons of southern Utah and northern Arizona. King's survey extended eastward from the High Sierra in California to Cheyenne, Wyoming, and encompassed a swath of country more than 100 miles wide. Hayden's explorations covered an immense region of mountains and basins from Yellowstone Park in Wyoming southeast throughout most of Colorado. Powell first entered the Uinta Mountains in the fall of 1868, having traveled north around the east end of the range from the White River country to Green River, Wyoming, then south over a circuitous route to Flaming Gorge and Browns Park, and finally back to the White River, where he spent the winter. In 1869, after reexamining much of the area visited the previous season, Powell embarked on his famous 'first boat trip' down the Green and Colorado Rivers. This trip was more exploratory than scientific; his second, more scientific trip was made 2 years later. Powell revisited the Uinta Mountains in 1874 and 1875 to complete the studies begun 6 years earlier. His classic 'Report on the Geology of the Eastern Portion of the Uinta Mountains and a Region of Country Adjacent Thereto' was published in 1876. King's survey?officially 'The United States Geological Exploration of the Fortieth Parallel'?is better known simply as the '40th Parallel Survey.' King began working eastward from California in 1867. The Uinta Mountains region, however, was mapped by S. F. Emmons, under the supervision of King, in the summers of 1869 and 1871. Emmons' work was monumental, and although he emphasized in his letter of transmittal to King the exploratory nature of the work?as the formal title of the report indicates?his maps, descriptions, and conclusions reflect a comprehensive understanding of the country and its rocks. The 40th Parallel report contains the best, most complete early descriptions of the Uinta Mountains. It, indeed, is a treasurechest of information and a landmark contribution to the emerging science of geology. Hayden visited the Uinta Mountains in 1870, descending the valley of Henrys Fork to Flaming Gorge in the fall after having earlier examined the higher part of the range to the west. Most of Hayden's observations were cursory, and he repeatedly expressed regret at having insufficient time for more detailed studies. In reference to the area between Clay Basin and Browns Park, he remarked (Hayden, 1871, p. 67) somewhat dryly that 'the geology of this portion of the Uinta range is very complicated and interesting. To have solved the problem to my entire satisfaction would have required a week or two.' Eighty-odd years later I spent several months there?looking at the same rocks. Powell was perhaps more creative?more intuitive?than either King or Hayden, and his breadth of interest in the fields of geology, physiography, ethnology, an

Bulletin↗
USGS2004

Geology of the National Capital Region: Field trip guidebook

The 2004 Joint Northeast-Southeast Section Meeting of the Geological Society of America is the fourth such meeting and the third to be held in or near Washington, D.C. This guidebook and the field trips presented herein are intended to provide meeting participants, as well as other interested readers, a means to understand and enjoy the rich geological and historical legacy of the National Capital Region. The field trips cover all of the major physiographic and geologic provinces of the central Appalachians in the Mid-Atlantic region. Trip 1 outlines the tectonic history of northern Virginia along an east-to-west transect from the Coastal Plain province to the Blue Ridge province, whereas the other field trips each focus on a specific province. From west to east, these excursions investigate the paleoclimate controls on the stratigraphy of the Paleozoic rocks of the Allegheny Plateau and Valley and Ridge province in West Virginia, Pennsylvania, and Maryland (Trip 3); Eocene volcanic rocks that intrude Paleozoic rocks in the westernmost Valley and Ridge province in Virginia and West Virginia (Trip 4); age, petrology, and structure of Mesoproterozoic gneisses and granitoids located in the Blue Ridge province within and near Shenandoah National Park, Virginia (Trip 2); the use of argon data to unravel the complex structural and thermal history of the metamorphic rocks of the eastern Piedmont province in Maryland and Virginia (Trip 5); the use of cosmogenic isotopes to understand the timing of bedrock incision and formation of terraces along the Potomac River in the eastern Piedmont province near Great Falls, Virginia and Maryland (Trip 6); the nature of the boundary between rocks of the Goochland and Chopawamsic terranes in the eastern Piedmont of Virginia (Trip 7); the role of bluffs and fluvial terraces of the Coastal Plain in the Civil War Battle of Fredericksburg, Virginia (Trip 8); and the Tertiary lithology and paleontology of Coastal Plain strata around the Chesapeake Bay of Virginia and Maryland (Trip 9). Some of the field trips present new geochronological research that uses isotopic techniques to unravel Earth history and processes, including U-Pb dating to determine the timing of metamorphism and igneous activity associated with the Mesoproterozoic Grenville orogeny (Trip 2); argon (4DAr/39Ar) analysis to understand the complex Paleozoic history of deformation and metamorphism in the Piedmont (Trip 5); and cosmogenic beryllium-10 data to derive exposure ages of landforms and deposits of the Potomac River valley (Trip 6). Several trips shed insight on significant or enigmatic geologic features of the region. Trip 3 presents evidence for global paleoclimate controls on the Paleozoic stratigraphy of the Appalachian basin, including evidence for Late Devonian glacial deposits. Trip 4 investigates unusual Eocene igneous rocks in the Eastern United States, and Trip 2 visits several local ductile high-strain zones, offering geologists opportunities to consider the importance of such structures relative to the poorly understood Rockfish Valley fault zone in the Blue Ridge province. In the Piedmont province, Trip 7 focuses on a controversial terrane boundary, whereas Trip 5 crosses several lithologic belts with distinct thermotectonic histories that suggest terrane boundaries. Trip 6 sheds new light on the erosional history of a major river gorge cut into crystalline rocks in the Fall Zone. Four trips are recommended for Earth science teachers and are cosponsored by the National Association of Geologic Teachers (NAGT). These trips focus on the tectonic history of northern Virginia (Trip 1), terraces of the Potomac River at Great Falls and cosmogenic isotope analysis to date the terraces and the incision history (Trip 6), and Tertiary lithology and paleontology of the Chesapeake Bay region (Trip 9). Trip 8 takes advantage of the rich Civil War history of this region to look at the role that geology played in the strategies and outcome of the Battle of Fredericksburg. This guidebook is the result of much hard work by many individuals. The editors wish to thank the field trip leaders and authors, the technical reviewers, and Nancy Stamm of ths USGS Geologic Names Committee. We also owe a very special thanks to Linda Gundersen, Chief Scientist, Geologic Discipline, USGS, who provided funding for the guidebook.

Maryland, Virginia, Washington DC↗
USGS2015

U.S. Geological Survey activities related to American Indians and Alaska Natives: Fiscal years 2009 and 2010

The U.S. Geological Survey is the earth and natural science bureau within the U.S. Department of the Interior. The U.S. Geological Survey provides impartial information on the health of our ecosystems and environment, the natural hazards that threaten us, the natural resources we rely on, the negative effects of climate and land-use change, and the core science systems that help us provide timely, relevant, and usable information. The U.S. Geological Survey is not responsible for regulations or land management. In the late 1800s, John Wesley Powell the second director of the U.S. Geological Survey, followed his interest in the Tribes of the Great Basin and Colorado Plateau and studied their cultures, languages, and surroundings. From that early time, the U.S. Geological Survey has recognized the importance of Native knowledge as a complement to the U.S. Geological Survey mission to better understand the Earth and its systems. Collaboration allows the U.S. Geological Survey and Native American governments, organizations, and peoples to increase their mutual understanding of the increasing challenges facing our natural world. Although this report uses the term “resources,” the U.S. Geological Survey, through its interdisciplinary research, acknowledges the interconnectedness of the Earth and all the life forms that live upon it.

Circular↗
USGS2026

Methodology for construction of a three-layer geologic model of the conterminous United States using land surface, top of bedrock, and top of basement

This report describes the methodology used for the construction of a digital three-layer geologic model of the conterminous United States by mapping the altitude of three surfaces: land surface, the top of bedrock, and the top of basement. These surfaces are mapped through the compilation and synthesis of published stratigraphic horizons from numerous topical studies. The mapped surfaces create a three-layer geologic model with three geomaterial-based subdivisions: unconsolidated to weakly consolidated sediment; layered consolidated rock strata that constitute bedrock; and crystalline rocks that are described as “basement,” consisting of either igneous, metamorphic, or highly deformed rocks. The data compilation and synthesis are highly dependent on the definition of the informal terms “bedrock” and “basement,” which may describe different ages or types of rock in different parts of the conterminous United States. This report presents the conceptualization of the three mapped layers, describes the datasets used, and summarizes the decisions made while compiling the three-layer model from the various sources. This digital dataset was created as part of efforts by the U.S. Geological Survey to develop subsurface geologic data in geospatial form as part of a broad directive to develop two-dimensional and three-dimensional geologic information at detailed, national, and continental scales. This digital dataset partly fulfills the goal of the U.S. Geological Survey’s National Cooperative Geologic Mapping Program to construct a national-scale three-dimensional geologic model.

conterminous United States↗
USGS2016

Digital geologic map data for the Ozark National Scenic Riverways and adjacent areas along the Current River and Jacks Fork, Missouri

The geology of the Ozark National Scenic Riverways (ONSR) in southern Missouri has been mapped at 1:24,000 scale. This endeavor was achieved through the combined efforts of U.S. Geological Survey and Missouri Geological Survey individual quadrangle mapping and additional fieldwork by the authors of this report. Geologic data covering the area of the ONSR and a 1-mile (1.6-kilometer) buffer zone surrounding the park, as well as geologic data from a few key adjoining areas, have been compiled into a single, seamless geographic information system database. The intent is to provide base geologic information for natural science research and land management in the park and surrounding areas. The data are served online at ScienceBase ( https://www.sciencebase.gov/catalog/ ), where they are provided in Environmental Systems Research Institute (ESRI) file geodatabase format, and are accompanied by metadata files. These data can be accessed at: http://dx.doi.org/10.5066/F7CJ8BKB . Additional detailed geologic information about the ONSR and surrounding areas is available in the separate 1:24,000-scale quadrangle maps and in a 1:100,000-scale map and report on the regional geology.

Missouri↗
USGS2005

Geologic Map Database of Texas

The purpose of this report is to release a digital geologic map database for the State of Texas. This database was compiled for the U.S. Geological Survey (USGS) Minerals Program, National Surveys and Analysis Project, whose goal is a nationwide assemblage of geologic, geochemical, geophysical, and other data. This release makes the geologic data from the Geologic Map of Texas available in digital format. Original clear film positives provided by the Texas Bureau of Economic Geology were photographically enlarged onto Mylar film. These films were scanned, georeferenced, digitized, and attributed by Geologic Data Systems (GDS), Inc., Denver, Colorado. Project oversight and quality control was the responsibility of the U.S. Geological Survey. ESRI ArcInfo coverages, AMLs, and shapefiles are provided.

Data Series↗
USGS2006

Digital geologic map and GIS database of Venezuela

The digital geologic map and GIS database of Venezuela captures GIS compatible geologic and hydrologic data from the 'Geologic Shaded Relief Map of Venezuela,' which was released online as U.S. Geological Survey Open-File Report 2005-1038. Digital datasets and corresponding metadata files are stored in ESRI geodatabase format; accessible via ArcGIS 9.X. Feature classes in the geodatabase include geologic unit polygons, open water polygons, coincident geologic unit linework (contacts, faults, etc.) and non-coincident geologic unit linework (folds, drainage networks, etc.). Geologic unit polygon data were attributed for age, name, and lithologic type following the Lexico Estratigrafico de Venezuela. All digital datasets were captured from source data at 1:750,000. Although users may view and analyze data at varying scales, the authors make no guarantee as to the accuracy of the data at scales larger than 1:750,000.

Data Series↗
USGS2020

Assessing geohazards to the Denali National Park road with geologic mapping

Denali National Park (DENA) is home to iconic and breathtaking landscapes surrounding the tallest mountain range in North America, the Alaska Range. The park, which covers 6 million acres, is a major draw for tourism and recreation, making it an important economic engine for central Alaska. However, the geologic forces that created the beautiful, steep landscape of DENA also make it prone to geologic hazards (geohazards) like landslides, debris flows, and earthquakes. DENA has only one major road, called the Park Road, that serves nearly all of its infrastructure. The success of DENA as a visitor destination, an economic engine, and a safe environment for visitors, residents, and staff relies on the resilience of this road, making it a major transportation lifeline for the region. Since 2017, the National Park Service and the U.S. Geological Survey National Cooperative Geologic Mapping Program have partnered to produce a new high-resolution geologic map of the Park Road corridor to identify and address ongoing geohazards affecting DENA infrastructure. In the area of Polychrome Overlook, this map is being used to guide a new route for the Park Road around an area of landslide-prone slopes, where ongoing slumping is costing National Park Service millions of dollars in annual road maintenance costs. Beyond this area, the map serves as a park resource to assess geohazard risk in future infrastructure and management decisions. Geologic mapping is also fueling new research in understanding the geologic and tectonic history of DENA, while training a new generation of geologic mappers through the USGS EDMAP program.

Alaksa↗
USGS1965

Aeromagnetic map of parts of Marquette, Dickinson, Baraga, Alger, and Schoolcraft Counties, Michigan, and its geologic interpretation

The U. S. Geological Survey, in cooperation with the Geological Survey Division of the Michigan Department of Conservation, is conducting a comprehensive restudy of the iron-bearing districts of Michigan. The use of aeromagnetic data is one of the fastest and most reliable methods for outlining the areal distribution of magnetic iron-formation and thus is of material value in assessing the iron resources of the United States. As part of this program of restudy, aeromagnetic surveys of approximately 4,500 square miles of the Northern Peninsula have been made. The results of several of these surveys have been presented by Balsley and others (1949) and by Wier and others (.1953). This report is about a survey made in 1950, over an area of about 1,400 square miles in Marquette County and ad-· joining strips in northern Dickinson and northeastern Baraga Counties, and a later survey flown in 1961, over about 500 square miles in parts of Marquette, Alger, and Schoolcraft Counties. The Marquette iron range extends in an east-west direction across approximately the west-central part of the area, and iron districts of lesser importance are located at Republic, in the southwestern part of the area, and near Gwinn, in the south -central part of the area. Aeromagnetic surveys were flown along north-south lines spaced at intervals of one-quarter mile in the western part of the area and at intervals of from about 1 to 3 miles in the eastern part. Lines were flown at approximately 500 feet above the surface or at elevations of 1,100 to 2,400 feet above sea level. The flight path of the aircraft was recorded by a gyrostabilized continuous-strip camera, and elevation was continuously recorded by a radio altimeter. Magnetic measurements were made by an AN/ASQ-3A fluxgate magnetometer. Compilation of aeromagnetic data was by standard methods, described by Balsley ( 1952 ), under the supervision of John Kirby and Frank Petrafeso. The aeromagnetic contours are relative to an arbitrary datum. Magnetic properties of rocks were measured by W. E. Huff. At the time the earlier aeromagnetic survey was flown, the only base maps available were planimetric maps such as the Helena NW quadrangle and county road maps. Small errors, therefore, may exist in the location of flight lines and specific aeromagnetic a nomalies. The major magnetic anomalies and broad areas that have characteristic magnetic patterns are correlated herein with geology as determined from published reports and from mapping done since 1957 by the U. S. Geological Survey in the eastern part of the Marquette iron range. The geology north of the Marquette iron range and west of the line between R. 25 W. and R. 26 W. is based mainly on a compilation made by Robert Reed of the Geological Survey Division of the Michigan Department of Conservation from data in the files of the State Survey. In addition some aeromagnetic features have been checked by ground magnetometer in selected localities and correlated directly with the rock types. A few oriented samples have been collected for measurement of the magnetic properties of the major rock units, but many hundreds or thousands of samples would be required to obtain a full range of values of the magnetic susceptibility and remanent magnetization of the rocks over such a large area. Although the geology of much of the area is still imperfectly known, the available aeromagnetic data together with the best obtainable geologic data are presented at this time, rather than awaiting the eventual extension or completion of the present mapping program, because the combined data provide much information on the extent and location of magnetic iron-formation and other major rock units where concealed beneath glacial, vegetative, and alluvial cover.

Michigan↗
USGS1991

Geologic map and profiles of the north wall of the Snake River Canyon, Thousand Springs and Niagara quadrangles, Idaho

The Snake River Plain is a broad, arcuate region of low relief that extends more than 300 mi across southern Idaho. The Snake River enters the plain near Idaho Falls and flows westward along the southern margin of the eastern Snake River Plain (fig. 1), a position mainly determined by the basaltic lava flows that erupted near the axis of the plain. The highly productive Snake River Plain aquifer north of the Snake River underlies most of the eastern plain. The aquifer is composed of basaltic rocks that are interbedded with fluvial and lacustrine sedimentary rocks. The top of the aquifer (water table) is typically less than 500 ft below the land surface but is deeper than 1,000 ft in a few areas. The Snake River has excavated a canyon into the nearly flat lying basaltic and sedimentary rocks of the eastern Snake River Plain aquifer, which discharges from the northern canyon wall as springs of variable size, spacing, and altitude. Geologic controls on springs are of importance because nearly 60 percent of the aquifer's discharge occurs as spring flow along the describes the geologic occurrence of springs along the northern wall of the Snake River canyon. This report is one of several that describes the geologic occurrence of springs along the northern wall of the Snake River canyon from Milner Dam to King Hill. To understand the local geologic controls on springs, the Water Resources Division of the U.S. Geological Survey initiated a geologic mapping project as part of their Snake River Plain Regional Aquifer System-Analysis Program. Objectives of the project were (1) to prepare a geologic map of a strip of land immediately north of the Snake River canyon, (2) to map the geology of the north canyon wall in profile, (3) to locate spring occurrences along the north side of the Snake River between Milner Sam and King Hill, and (4) to estimate spring discharge from the north wall of the canyon.

Idaho↗
USGS2001

Geologic Map of the Hellas Region of Mars

INTRODUCTION This geologic map of the Hellas region focuses on the stratigraphic, structural, and erosional histories associated with the largest well-preserved impact basin on Mars. Along with the uplifted rim and huge, partly infilled inner basin (Hellas Planitia) of the Hellas basin impact structure, the map region includes areas of ancient highland terrain, broad volcanic edifices and deposits, and extensive channels. Geologic activity recorded in the region spans all major epochs of martian chronology, from the early formation of the impact basin to ongoing resurfacing caused by eolian activity. The Hellas region, whose name refers to the classical term for Greece, has been known from telescopic observations as a prominent bright feature on the surface of Mars for more than a century (see Blunck, 1982). More recently, spacecraft imaging has greatly improved our visual perception of Mars and made possible its geologic interpretation. Here, our mapping at 1:5,000,000 scale is based on images obtained by the Viking Orbiters, which produced higher quality images than their predecessor, Mariner 9. Previous geologic maps of the region include those of the 1:5,000,000-scale global series based on Mariner 9 images (Potter, 1976; Peterson, 1977; King, 1978); the 1:15,000,000-scale global series based on Viking images (Greeley and Guest, 1987; Tanaka and Scott, 1987); and detailed 1:500,000-scale maps of Tyrrhena Patera (Gregg and others, 1998), Dao, Harmakhis, and Reull Valles (Price, 1998; Mest and Crown, in press), Hadriaca Patera (D.A. Crown and R. Greeley, map in preparation), and western Hellas Planitia (J.M. Moore and D.E. Wilhelms, map in preparation). We incorporated some of the previous work, but our map differs markedly in the identification and organization of map units. For example, we divide the Hellas assemblage of Greeley and Guest (1987) into the Hellas Planitia and Hellas rim assemblages and change the way units within these groupings are identified and mapped (table 1). The new classification scheme includes broad, geographically related categories and local, geologically and geomorphically related subgroups. Because of our mapping at larger scale, many of our map units were incorporated within larger units of the global-scale mapping (see table 1). Available Viking images of the Hellas region vary greatly in several aspects, which has complicated the task of producing a consistent photogeologic map. Best available image resolution ranges from about 30 to 300 m/pixel from place to place. Many images contain haze caused by dust clouds, and contrast and shading vary among images because of dramatic seasonal changes in surface albedo, opposing sun azimuths, and solar inclination. Enhancement of selected images on a computer-display system has greatly improved our ability to observe key geologic relations in several areas. Determination of the geologic history of the region includes reconstruction of the origin and sequence of formation, deformation, and modification of geologic units constituting (1) the impact-basin rim and surrounding highlands, (2) volcanic and channel assemblages on the northeast and south sides of the basin, (3) interior basin deposits, and (4) slope and surficial materials throughout the map area. Various surface modifications are attributed to volcanic, fluvial, eolian, mass-wasting, and possibly glacial and periglacial processes. Structures include basin faults (mostly inferred), wrinkle ridges occurring mainly in volcanic terrains and interior plains, volcanic collapse craters, and impact craters. Our interpretations in some cases rely on previous work, but in many significant cases we have offered new interpretations that we believe are more consistent with the observations documented by our mapping. Our primary intent for this mapping has been to elucidate the history of emplacement and modification of Hellas Planitia materials, which form the basis for analysis of their r

IMAP↗
USGS2001

Geologic map of the San Bernardino North 7.5' quadrangle, San Bernardino County, California

Introduction Open-File Report OF 01-131 contains a digital geologic map database of the San Bernardino North 7.5’ quadrangle, San Bernardino County, California that includes: 1. ARC/INFO (Environmental Systems Research Institute) version 7.2.1 coverages of the various components of the geologic map 2. A PostScript file to plot the geologic map on a topographic base, and containing a Correlation of Map Units (CMU) diagram, a Description of Map Units (DMU), an index map, and a regional structure map. 3. Portable Document Format (.pdf) files of: a. This Readme; includes an Appendix, containing data found in sbnorth_met.txt . b. The Description of Map Units identical to that found on the plot of the PostScript file. c. The same graphic as plotted in 2 above. (Test plots from this .pdf do not produce 1:24,000-scale maps. Use Adobe Acrobat pagesize setting to control map scale.) The Correlation of Map Units and Description of Map Units is in the editorial format of USGS Miscellaneous Investigations Series (I-series) maps. Within the geologic map data package, map units are identified by standard geologic map criteria such as formation-name, age, and lithology. Even though this is an author-prepared report, every attempt has been made to closely adhere 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). If roads in some areas, especially forest roads that parallel topographic contours, do not show well on plots of the geologic map, we recommend use of the USGS San Bernardino North 7.5’ topographic quadrangle in conjunction with the geologic map.

California↗
USGS2001

Geologic map of the Fifteenmile Valley 7.5' quadrangle, San Bernardino County, California

Open-File Report OF 01-132 contains a digital geologic map database of the Fifteenmile Valley 7.5’ quadrangle, San Bernardino 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, a Description of Map Units, an index map, and a regional structure map. 3. Portable Document Format (.pdf) files of: a. This Readme; includes in Appendix I, data contained in fif_met.txt b. The same graphic as plotted in 2 above. (Test plots have not produced 1:24,000-scale map sheets. Adobe Acrobat pagesize setting influences map scale.) The Correlation of Map Units (CMU) and Description of Map Units (DMU) is in the editorial format of USGS Miscellaneous Investigations Series (I-series) maps. Within the geologic map data package, map units are identified by standard geologic map criteria such as formation-name, age, and lithology. Even though this is an author-prepared report, every attempt has been made to closely adhere 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). If roads in some areas, especially forest roads that parallel topographic contours, do not show well on plots of the geologic map, we recommend use of the USGS Fifteenmile Valley 7.5’ topographic quadrangle in conjunction with the geologic map.

California↗
USGS2001

Geologic map of the Devore 7.5' quadrangle, San Bernardino County, California

This Open-File Report contains a digital geologic map database of the Devore 7.5' quadrangle, San Bernardino County, California, that includes: 1. ARC/INFO (Environmental Systems Research Institute) version 7.2.1 coverages of the various components of the geologic map 2. A PostScript (.ps) file to plot the geologic map on a topographic base, containing a Correlation of Map Units diagram, a Description of Map Units, an index map, and a regional structure map 3. Portable Document Format (.pdf) files of: a. This Readme; includes an Appendix, containing metadata details found in devre_met.txt b. The same graphic as plotted in 2 above. (Test plots from this .pdf do not produce 1:24,000-scale maps. Adobe Acrobat page-size settings control map scale.) The Correlation of Map Units and Description of Map Units are in the editorial format of USGS Miscellaneous Investigations Series maps (I-maps) but have not been edited to comply with I-map standards. Within the geologic-map data package, map units are identified by such standard geologic-map criteria as formation name, age, and lithology. Even though this is an author-prepared report, every attempt has been made to closely adhere 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). If roads in some areas, especially forest roads that parallel topographic contours, do not show well on plots of the geologic map, we recommend use of the USGS Devore 7.5’ topographic quadrangle in conjunction with the geologic map.

California↗
USGS2001

Geologic map of the Telegraph Peak 7.5' quadrangle, San Bernardino County, California

Open-File Report OF 01-293 contains a digital geologic map database of the Telegraph Peak 7.5’ quadrangle, San Bernardino County, California that includes: ARC/INFO (Environmental Systems Research Institute, http://www.esri.com) version 7.2.1 double precision coverages of the various elements of the geologic map. A PostScript file to plot the geologic map on a topographic base, and containing a Correlation of Map Units diagram, a Description of Map Units, an index map, and a regional structure map. Portable Document Format (.pdf) files of: a. This Readme; includes in Appendix I, data contained in fif_met.txt b. The same graphic as plotted in 2 above. Test plots have not produced 1:24,000-scale map sheets. Adobe Acrobat pagesize setting influences map scale. The Correlation of Map Units and Description of Map Units is in the editorial format of USGS Miscellaneous 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. Even though this is an author-prepared report, every attempt has been made to closely adhere 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). If roads in some areas, especially forest roads that parallel topographic contours, do not show well on plots of the geologic map, we recommend use of the USGS Telegraph Peak 7.5’ topographic quadrangle in conjunction with the geologic map.

California↗
USGS2001

Geologic map of the Cucamonga Peak 7.5' quadrangle, San Bernardino County, California

Open-File Report OF 01-311 contains a digital geologic map database of the Cucamonga Peak 7.5’ quadrangle, San Bernardino 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, a Description of Map Units, an index map, and a regional structure map 3. Portable Document Format (.pdf) files of: a. This Readme; includes in Appendix I, data contained in fif_met.txt b. The same graphic as plotted in 2 above. (Test plots have not produced 1:24,000-scale map sheets. Adobe Acrobat pagesize setting influences map scale.) The Correlation of Map Units and Description of Map Units is in the editorial format of USGS Miscellaneous 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. Even though this is an author-prepared report, every attempt has been made to closely adhere 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). If roads in some areas, especially forest roads that parallel topographic contours, do not show well on plots of the geologic map, we recommend use of the USGS Cucamonga Peak 7.5’ topographic quadrangle in conjunction with the geologic map.

California↗