This digital map shows the geographic extent of rock stratigraphic units (formations) as compiled by Colton in 1976 under the Front Range Urban Corridor Geology Program. Colton used his own geologic mapping and previously published geologic maps to compile one map having a single classification of geologic units. The resulting published color paper map (USGS Map I-855-G, Colton, 1978) was intended for land-use planning and to depict the regional geology. In 1997-1999, another USGS project designed to address urban growth issues was undertaken. This project, the USGS Front Range Infrastructure Resources Project, undertook to digitize Colton's map at 1:100,000 scale, making it useable in Geographical Information Systems (GIS). That product is described here. In general, the digitized map depicts in its western part Precambrian igneous and metamorphic rocks, Pennsylvanian and younger sedimentary rock units, major faults, and brecciated zones along an eastern strip (5-20 km wide) of the Front Range. The central and eastern parts of the map (Colorado Piedmont) show a mantle of Quaternary unconsolidated deposits and interspersed outcrops of sedimentary rock of Cretaceous or Tertiary age. A surficial mantle of unconsolidated deposits of Quaternary age is differentiated and depicted as eolium (wind-blown sand and silt), alluvium (river gravel, sand, and silt of variable composition), colluvium, and a few landslide deposits. At the mountain front, north-trending, Paleozoic and Mesozoic formations of sandstone, shale, and minor limestone dip mostly eastward and form folds, fault blocks, hogbacks and intervening valleys. Local dikes and sills of Tertiary rhyodacite and basalt intrude rocks near the range front, mostly in the Boulder area.

This digital map shows the areal extent of surficial deposits and rock stratigraphic units (formations) as compiled by Trimble and Machette from 1973 to 1977 and published in 1979 under the Front Range Urban Corridor Geology Program. Trimble and Machette compiled their geologic map from published geologic maps and unpublished geologic mapping having varied map unit schemes. A convenient feature of the compiled map is its uniform classification of geologic units that mostly matches those of companion maps to the north (USGS I-855-G) and to the south (USGS I-857-F). Published as a color paper map, the Trimble and Machette map was intended for land-use planning in the Front Range Urban Corridor. This map recently (1997-1999) was digitized under the USGS Front Range Infrastructure Resources Project. In general, the mountainous areas in the western part of the map exhibit various igneous and metamorphic bedrock units of Precambrian age, major faults, and fault brecciation zones at the east margin (5-20 km wide) of the Front Range. The eastern and central parts of the map (Colorado Piedmont) depict a mantle of unconsolidated deposits of Quaternary age and interspersed outcroppings of Cretaceous or Tertiary-Cretaceous sedimentary bedrock. The Quaternary mantle comprises eolian deposits (quartz sand and silt), alluvium (gravel, sand, and silt of variable composition), colluvium, and a few landslides. At the mountain front, north-trending, dipping Paleozoic and Mesozoic sandstone, shale, and limestone bedrock formations form hogbacks and intervening valleys.

This digital map shows the areal extent of surficial deposits and rock stratigraphic units (formations) as compiled by Trimble and Machette from 1973 to 1977 and published in 1979 under the Front Range Urban Corridor Geology Program. Trimble and Machette compiled their geologic map from published geologic maps and unpublished geologic mapping having varied map unit schemes. A convenient feature of the compiled map is its uniform classification of geologic units that mostly matches those of companion maps to the north (USGS I-855-G) and to the south (USGS I-857-F). Published as a color paper map, the Trimble and Machette map was intended for land-use planning in the Front Range Urban Corridor. This map recently (1997-1999) was digitized under the USGS Front Range Infrastructure Resources Project. In general, the mountainous areas in the western part of the map exhibit various igneous and metamorphic bedrock units of Precambrian age, major faults, and fault brecciation zones at the east margin (5-20 km wide) of the Front Range. The eastern and central parts of the map (Colorado Piedmont) depict a mantle of unconsolidated deposits of Quaternary age and interspersed outcroppings of Cretaceous or Tertiary-Cretaceous sedimentary bedrock. The Quaternary mantle comprises eolian deposits (quartz sand and silt), alluvium (gravel, sand, and silt of variable composition), colluvium, and a few landslides. At the mountain front, north-trending, dipping Paleozoic and Mesozoic sandstone, shale, and limestone bedrock formations form hogbacks and intervening valleys.

This geologic database is a digitized version of the original 1:24,000-scale analog geologic map titled "Geologic map of the Vidal, California, and Parker SW, California-Arizona quadrangles", published by the U.S. Geological Survey (USGS) in 1980. The map area straddles the Arizona-California border, and is located approximately 9.0 km (5.6 mi) west-southwest of Parker, CA, immediately south of the unincorporated communities of Vidal and Vidal Junction, CA. The map area includes the northern Riverside Mountains, which contain a prominent suite of Permian, Mesozoic, and potentially Precambrian metamorphic and metasedimentary rocks. These rocks predominantly consist of gneisses, schists, limestones, and dolomites, separated by three mapped structural discontinuities and the prominent Whipple Mountains Detachment Fault. The map area additionally contains small outcrops of Miocene intermediate-to-felsic volcanic rocks consisting of basaltic andesite flows, andesitic porphyry, rhyolitic intrusives, and the Peach Springs Tuff. The Riverside Mountains are surrounded by numerous sedimentary units, largely consisting of fluvial deposits, that record the arrival and subsequent fluctuations of the Colorado River in the region from the Pliocene through the Holocene. These sedimentary units additionally record Quaternary alluvial fan processes on the flanks of the Riverside Mountains and in the lower Vidal Valley.

This geologic database is a digitized version of the original 1:24,000-scale analog geologic map titled "Geologic map of the Vidal, California, and Parker SW, California-Arizona quadrangles", published by the U.S. Geological Survey (USGS) in 1980. The map area straddles the Arizona-California border, and is located approximately 9.0 km (5.6 mi) west-southwest of Parker, CA, immediately south of the unincorporated communities of Vidal and Vidal Junction, CA. The map area includes the northern Riverside Mountains, which contain a prominent suite of Permian, Mesozoic, and potentially Precambrian metamorphic and metasedimentary rocks. These rocks predominantly consist of gneisses, schists, limestones, and dolomites, separated by three mapped structural discontinuities and the prominent Whipple Mountains Detachment Fault. The map area additionally contains small outcrops of Miocene intermediate-to-felsic volcanic rocks consisting of basaltic andesite flows, andesitic porphyry, rhyolitic intrusives, and the Peach Springs Tuff. The Riverside Mountains are surrounded by numerous sedimentary units, largely consisting of fluvial deposits, that record the arrival and subsequent fluctuations of the Colorado River in the region from the Pliocene through the Holocene. These sedimentary units additionally record Quaternary alluvial fan processes on the flanks of the Riverside Mountains and in the lower Vidal Valley.

This geologic database is a digitized version of the original 1:24,000-scale analog geologic map titled "Geologic map of the Vidal, California, and Parker SW, California-Arizona quadrangles", published by the U.S. Geological Survey (USGS) in 1980. The map area straddles the Arizona-California border, and is located approximately 9.0 km (5.6 mi) west-southwest of Parker, CA, immediately south of the unincorporated communities of Vidal and Vidal Junction, CA. The map area includes the northern Riverside Mountains, which contain a prominent suite of Permian, Mesozoic, and potentially Precambrian metamorphic and metasedimentary rocks. These rocks predominantly consist of gneisses, schists, limestones, and dolomites, separated by three mapped structural discontinuities and the prominent Whipple Mountains Detachment Fault. The map area additionally contains small outcrops of Miocene intermediate-to-felsic volcanic rocks consisting of basaltic andesite flows, andesitic porphyry, rhyolitic intrusives, and the Peach Springs Tuff. The Riverside Mountains are surrounded by numerous sedimentary units, largely consisting of fluvial deposits, that record the arrival and subsequent fluctuations of the Colorado River in the region from the Pliocene through the Holocene. These sedimentary units additionally record Quaternary alluvial fan processes on the flanks of the Riverside Mountains and in the lower Vidal Valley.

This data release contains a digital compilation of geologic data from the Scottsbluff 1° x 2° quadrangle of western Nebraska and northeastern Colorado, a region predominantly characterized by Quaternary and Tertiary sedimentary and extrusive igneous rocks. This geodatabase, digitized from published resources, includes the position of volcanic ash-bed localities, structural data of inclined beds, orientation of geologic contacts and structural contours of specified stratigraphic horizons, and geographic extent of mapped geologic outcrops. This geologic compilation includes a geodatabase with applicable spatial feature classes accompanied by non-spatial tables with information that describes the data sources, glossary of terms, and description of map units. Spatial data are also available as shapefiles.

This data release contains a digital compilation of geologic data from the Scottsbluff 1° x 2° quadrangle of western Nebraska and northeastern Colorado, a region predominantly characterized by Quaternary and Tertiary sedimentary and extrusive igneous rocks. This geodatabase, digitized from published resources, includes the position of volcanic ash-bed localities, structural data of inclined beds, orientation of geologic contacts and structural contours of specified stratigraphic horizons, and geographic extent of mapped geologic outcrops. This geologic compilation includes a geodatabase with applicable spatial feature classes accompanied by non-spatial tables with information that describes the data sources, glossary of terms, and description of map units. Spatial data are also available as shapefiles.

This geologic database is a digitized version of the original 1:24,000-scale analog geologic map titled "Geologic map of the Parker NW, Parker, and parts of the Whipple Mountains SW and Whipple Wash quadrangles, California and Arizona", published by the U.S. Geological Survey (USGS) in 1980. The map area straddles the Arizona-California border and includes the community of Parker, AZ, and the southeastern part of the Whipple Mountains, where the prominent Whipple Mountains Detachment Fault separates lower plate Cretaceous and older gneisses from upper plate crystalline, volcanic, and sedimentary rocks. The Whipple Mountains are surrounded by numerous Neogene sedimentary units that record the arrival and subsequent fluctuations of the Colorado River in the region from the Pliocene through the Holocene, as well as Quaternary alluvial fan processes on the southern flank of the Whipple Mountains and in lower Vidal Valley.

This geologic database is a digitized version of the original 1:24,000-scale analog geologic map titled "Geologic map of the Parker NW, Parker, and parts of the Whipple Mountains SW and Whipple Wash quadrangles, California and Arizona", published by the U.S. Geological Survey (USGS) in 1980. The map area straddles the Arizona-California border and includes the community of Parker, AZ, and the southeastern part of the Whipple Mountains, where the prominent Whipple Mountains Detachment Fault separates lower plate Cretaceous and older gneisses from upper plate crystalline, volcanic, and sedimentary rocks. The Whipple Mountains are surrounded by numerous Neogene sedimentary units that record the arrival and subsequent fluctuations of the Colorado River in the region from the Pliocene through the Holocene, as well as Quaternary alluvial fan processes on the southern flank of the Whipple Mountains and in lower Vidal Valley.