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 Trimble and Machette compiled their geologic map from published geologic maps and unpublished geologic mapping having varied map unit schemes.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 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 database release contains elevation surfaces on 24 surfaces representing the tops of geological formations in the Denver Basin. These surfaces were exported as raster data from Leapfrog software, in which the model was constructed. Inputs to the model include well top data compiled from state agencies, formation contacts extracted from the Stage Geological Map Compilation, and structural elevation contours from Colorado and Wyoming state agencies and USGS water studies. These data are not included in this release. However, the sources are documented in the included DataSources table to allow retrieval of source data, should it be desired by the user. Other Non-Spatial tables include a Description of Model Units, describing the geology of each formation included as a unit in the model, a Glossary of terms, and a GeoMaterialDict table with terms common to GeMS-formatted databases. The EntityAndAttribute_DataDictionary_DenverBasin.csv file provides a listing of all outputs included in this release. DenverBasinInputSummaryTable.csv documents settings used to build the model (boundary filter, snapping, data sources, etc.) Three faults were used in the construction of the model. The Rocky Mountain Front reverse fault cuts the model from north to south. The Hartville Fault terminates against the Rocky Mountain Front in Wyoming. Finally, the Laramie Fault of Wyoming forms the edge of the study area in the northwest of the model. These faults are included as grids of points in point feature classes. The Denver Basin is a sedimentary basin primarily located in northeastern Colorado, with portions in Wyoming, Nebraska, and Kansas. The basin is bounded by the Hartville Uplift in Wyoming, the Chadron and Cambridge Arches of Nebraska, the Las Animas Arch in Colorado and Kansas, and the Apishapa Uplift in Colorado. The fault-bounded Rocky Mountain Front forms the western boundary of the model. Thrust faulting and sediment loading associated with the Rocky Mountain Front created the asymmetric shape of the Denver Basin, with a foredeep centered near Boulder, Colorado. Broad changes in geology can be seen in this Denver Basin model, from a Paleozoic-dominated carbonate platform near the Las Animas Arch transitioning to Penn-Perm clastics shed off the Ancestral Rocky Mountains. Other geologic features of interest visible within the model include Red Rocks Amphitheater in Morrison, CO, Garden of the Gods Park near Colorado Springs, and an interpretation of the Ralston Dike and associated Table Mountain volcanics near Golden, Colorado.

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 digital data release contains geospatial geologic and paleontological data of the 1° x2 °, 1:250,000 Limon quadrangle covering eastern Colorado and western Kansas. The dataset is a digital reproduction of previously published U.S. Geological Survey field mapping which illustrates the spatial configuration of primarily Quaternary surficial units overlying upper Miocene, Oligocene, Paleocene, and Upper Cretaceous bedrock (Sharps, 1980). This quadrangle contains numerous outcrop of the Ogallala Formation, which is a prolific freshwater aquifer throughout the broader great plains. A structure contour map of the top of the Dakota Sandstone are included, which was constructed using selected oil and gas well logs (Sharps, 1980). The Dakota Sandstone is a productive hydrocarbon reservoir within the Limon quadrangle, and the broader Denver-Julesburg Basin. Point data for Mesozoic invertebrate fossil collection localities are depicted on the map, depicted with either Denver or Washington D.C. U.S. Geological Survey catalog numbers (Sharps, 1980). The digital geologic database presented here is an accurate replication of original US. Geological Survey mapping in the Limon quadrangle (Sharps, 1980). Geologic map polygons, fossil points, faunal zones, and structure contours were digitized and attributed as GIS data sets as part of the U.S. Geological Survey’s ongoing studies on a regional and national scale. The geologic map polygons, fossil point features, faunal zone lines, and structure contour lines are distributed as separate feature classes within a geographic information system geodatabase. Contoured elevation values are given in feet, to maintain consistency with the original publication, and in meters. Nonspatial tables define the data sources used, define terms used in the dataset, and describe the geologic units. A tabular data dictionary describes the entity and attribute information for all attributes of the geospatial data and the accompanying nonspatial tables.

This digital data release contains geospatial geologic and paleontological data of the 1° x2 °, 1:250,000 Limon quadrangle covering eastern Colorado and western Kansas. The dataset is a digital reproduction of previously published U.S. Geological Survey field mapping which illustrates the spatial configuration of primarily Quaternary surficial units overlying upper Miocene, Oligocene, Paleocene, and Upper Cretaceous bedrock (Sharps, 1980). This quadrangle contains numerous outcrop of the Ogallala Formation, which is a prolific freshwater aquifer throughout the broader great plains. A structure contour map of the top of the Dakota Sandstone are included, which was constructed using selected oil and gas well logs (Sharps, 1980). The Dakota Sandstone is a productive hydrocarbon reservoir within the Limon quadrangle, and the broader Denver-Julesburg Basin. Point data for Mesozoic invertebrate fossil collection localities are depicted on the map, depicted with either Denver or Washington D.C. U.S. Geological Survey catalog numbers (Sharps, 1980). The digital geologic database presented here is an accurate replication of original US. Geological Survey mapping in the Limon quadrangle (Sharps, 1980). Geologic map polygons, fossil points, faunal zones, and structure contours were digitized and attributed as GIS data sets as part of the U.S. Geological Survey’s ongoing studies on a regional and national scale. The geologic map polygons, fossil point features, faunal zone lines, and structure contour lines are distributed as separate feature classes within a geographic information system geodatabase. Contoured elevation values are given in feet, to maintain consistency with the original publication, and in meters. Nonspatial tables define the data sources used, define terms used in the dataset, and describe the geologic units. A tabular data dictionary describes the entity and attribute information for all attributes of the geospatial data and the accompanying nonspatial tables.

This release contains geospatial data digitized from the Map Showing Geology, Structure, and Oil and Gas Fields in the Sterling 1x2 Degree Quadrangle, Colorado, Nebraska, and Kansas (Scott, 1978) and was compiled as part of the National Geologic Synthesis project. The geospatial data depicts the geology of this quadrangle, which is dominated by Quaternary alluvial and aeolian deposits overlying Tertiary and Cretaceous sedimentary rock, including the Ogallala formation, the Fox Hills sandstone, and the Pierre shale. The included database includes spatial data depicting the locations of mapped geologic contacts and faults, polygons denoting the mapped surficial extent of geologic formations, and structural contours denoting the depth to the top of the D sandstone of the Dakota Group. The database also contains non-spatial tables, including a list of data sources, a description of map units, a glossary of terms, and a data dictionary.

This release contains geospatial data digitized from the Map Showing Geology, Structure, and Oil and Gas Fields in the Sterling 1x2 Degree Quadrangle, Colorado, Nebraska, and Kansas (Scott, 1978) and was compiled as part of the National Geologic Synthesis project. The geospatial data depicts the geology of this quadrangle, which is dominated by Quaternary alluvial and aeolian deposits overlying Tertiary and Cretaceous sedimentary rock, including the Ogallala formation, the Fox Hills sandstone, and the Pierre shale. The included database includes spatial data depicting the locations of mapped geologic contacts and faults, polygons denoting the mapped surficial extent of geologic formations, and structural contours denoting the depth to the top of the D sandstone of the Dakota Group. The database also contains non-spatial tables, including a list of data sources, a description of map units, a glossary of terms, and a data dictionary.