This geologic map database compiles, in digital form, geologic data previously published as printed maps showing the altitude of the base of Dakota Sandstone and equivalent rocks on the Colorado Plateau in Arizona, Colorado, New Mexico, and Utah. Data were compiled from U.S. Geological Survey 1:250,000-scale geologic maps and other topical maps that included structure contours of the base of the Dakota Sandstone. Surface and subsurface data compiled include mapped polygons of the Dakota Sandstone and equivalent units, faults, fold axes, structure contours, and bedding attitudes calculated from the structure contours. All data were compiled as a GeMS digital database. This digital geologic database is a companion dataset to an interpretive USGS report "Methodology for Compilation of Previously Published Contour Data Showing the Altitude of the Base of Dakota Sandstone on the Colorado Plateau, Arizona, Colorado, New Mexico, and Utah". These digital data are a compilation of data from previously published maps of the base of the Dakota Formation made digital for the first time, providing a digital dataset for future scientific and resource evaluations of the Colorado Plateau region. The dataset includes a geographic information system geodatabase that contains mapped contacts and faults, map unit polygons of the Dakota Sandstone and stratigraphic equivalents, fold axes, structure contour lines, and point data of bedding attitudes. Vector data are attributed according to the USGS National Cooperative Geologic Mapping Program’s GeMS digital geologic map schema. The spatial data are accompanied by non-spatial tables that describe the sources of geologic information, a description of geologic map units, a glossary of terms, and a Data Dictionary that duplicates the Entity and Attribute information contained in the metadata file. To maximize usability, spatial data are also distributed as shapefiles and tabular data are distributed as ascii text files in comma separated values (CSV) format.

The Upper Colorado River Basin has a drainage area of about 113,500 square miles in western Colorado, eastern Utah, southwestern Wyoming, northeastern Arizona, and northwestern New Mexico. In the 1980’s and 1990’s, the Upper Colorado River Basin was a study area under of the U.S. Geological Survey's Regional Aquifer-System Analysis (RASA) program (Sun and Johnston, 1994; Sun and Weeks, 1991). The objectives of the RASA program for the Upper Colorado River Basin were to provide regional assessments of major aquifer systems by providing quantitative assessments of the occurrence, movement, and availability of water stored in rock formations that underlie the basin/watershed. These assessments included: (1) the classification of stratigraphic sequences into those intervals that constitute aquifers and those that constitute confining beds; and (2) the generation of maps that portrayed the areal extent of aquifers, aquifer thickness, and overburden thickness. These studies generated a large body of subsurface geologic information as part of the regional aquifer analyses, some of which are captured in this digital data release. Aquifer systems in consolidated rocks in the Upper Colorado River Basin have been grouped into three major subdivisions of sedimentary rocks; in descending order: (1) Tertiary-rock aquifers, (2) Mesozoic-rock aquifers, and (3) Paleozoic-rock aquifers (Taylor and others, 1983; 1986). Within each aquifer group, rocks are further divided into aquifers and confining units on the basis of lithology, depositional environment, and hydrologic characteristics (Glover and others, 1998; Freethy and Cordy, 1991; Geldon, 2003). In a report describing consolidated-rock aquifers of Mesozoic age, 10 hydrostratigraphic units were defined, five aquifers and five confining units (Freethy and Cordy, 1991). The hydrostratigraphic units of Mesozoic age occur throughout the Upper Colorado River Basin study area, except in parts of the Uinta, White River, and San Juan uplifts where they have been removed by erosion. These hydrostratigraphic units are part of the stratigraphic sequence of Mesozoic rocks that has a total thickness of more than 8,000 ft. The sandstones of Mesozoic age are the most areally extensive and the thickest bedrock aquifers in the Upper Colorado River Basin. This digital dataset contains spatial datasets corresponding to the contoured subsurface maps produced by the U.S. Geological Survey's Regional Aquifer-System Analysis (RASA) of the Upper Colorado River Basin (Freethy and Cordy, 1991). The data define the thickness and extent of principal hydrostratigraphic units of Mesozoic age in the basin. The digital data describe the following hydrostratigraphic units: the Chinle-Moenkopi confining unit, the Navajo-Nugget aquifer, the Carmel-Twin Creek confining unit, the Entrada-Preuss aquifer, the Curtis-Stump confining unit, the Morrison aquifer, the Morrison confining unit, the Dakota aquifer, the Mancos confining unit, and the Mesaverde aquifer. Contoured thickness data for each unit are contained in line features classes within a geodatabase; unit extents are represented as polygon feature classes. Both types of data are also saved as individual shapefiles. Nonspatial tables define the data sources used, and the stacking hierarchy and component geologic formations of each the of hydrostratigraphic units.

The Upper Colorado River Basin has a drainage area of about 113,500 square miles in western Colorado, eastern Utah, southwestern Wyoming, northeastern Arizona, and northwestern New Mexico. In the 1980’s and 1990’s, the Upper Colorado River Basin was a study area under of the U.S. Geological Survey's Regional Aquifer-System Analysis (RASA) program (Sun and Johnston, 1994; Sun and Weeks, 1991). The objectives of the RASA program for the Upper Colorado River Basin were to provide regional assessments of major aquifer systems by providing quantitative assessments of the occurrence, movement, and availability of water stored in rock formations that underlie the basin/watershed. These assessments included: (1) the classification of stratigraphic sequences into those intervals that constitute aquifers and those that constitute confining beds; and (2) the generation of maps that portrayed the areal extent of aquifers, aquifer thickness, and overburden thickness. These studies generated a large body of subsurface geologic information as part of the regional aquifer analyses, some of which are captured in this digital data release. Aquifer systems in consolidated rocks in the Upper Colorado River Basin have been grouped into three major subdivisions of sedimentary rocks; in descending order: (1) Tertiary-rock aquifers, (2) Mesozoic-rock aquifers, and (3) Paleozoic-rock aquifers (Taylor and others, 1983; 1986). Within each aquifer group, rocks are further divided into aquifers and confining units on the basis of lithology, depositional environment, and hydrologic characteristics (Glover and others, 1998; Freethy and Cordy, 1991; Geldon, 2003). In a report describing consolidated-rock aquifers of Mesozoic age, 10 hydrostratigraphic units were defined, five aquifers and five confining units (Freethy and Cordy, 1991). The hydrostratigraphic units of Mesozoic age occur throughout the Upper Colorado River Basin study area, except in parts of the Uinta, White River, and San Juan uplifts where they have been removed by erosion. These hydrostratigraphic units are part of the stratigraphic sequence of Mesozoic rocks that has a total thickness of more than 8,000 ft. The sandstones of Mesozoic age are the most areally extensive and the thickest bedrock aquifers in the Upper Colorado River Basin. This digital dataset contains spatial datasets corresponding to the contoured subsurface maps produced by the U.S. Geological Survey's Regional Aquifer-System Analysis (RASA) of the Upper Colorado River Basin (Freethy and Cordy, 1991). The data define the thickness and extent of principal hydrostratigraphic units of Mesozoic age in the basin. The digital data describe the following hydrostratigraphic units: the Chinle-Moenkopi confining unit, the Navajo-Nugget aquifer, the Carmel-Twin Creek confining unit, the Entrada-Preuss aquifer, the Curtis-Stump confining unit, the Morrison aquifer, the Morrison confining unit, the Dakota aquifer, the Mancos confining unit, and the Mesaverde aquifer. Contoured thickness data for each unit are contained in line features classes within a geodatabase; unit extents are represented as polygon feature classes. Both types of data are also saved as individual shapefiles. Nonspatial tables define the data sources used, and the stacking hierarchy and component geologic formations of each the of hydrostratigraphic units.

This digital dataset release of the Tectonic Map of the Colorado Plateau is a courtesy publication of the previously published legacy report by V.C. Kelley in 1955. The original publication, "Tectonic Map of the Colorado Plateau Showing Uranium Deposits" contains elevation contours from the top of the Chinle formation in 1000 ft intervals and geologic structural formations such as monoclinal, synclinal, and anticlinal structures. The digitizing of this map is to provide a more accessible dataset to be available for public usage. The original dataset was in relation to a larger project by the University of New Mexico and their publications in geology of uranium distributions throughout the Colorado Plateau (Kelley, V.C., 1955, Regional tectonics of the Colorado Plateau and relationship to the origin and distribution of uranium: Albuquerque, University of New Mexico, Publications in Geology no. 5, 120 p., 1 sheet, scale 1:1,000,000.). The entirety of this dataset includes both spatial and non-spatial data held in a singular, GeMS compliant geodatabase. This geodatabase includes a geologic map feature dataset holding fault lines, iso value lines, structure contours, and other geologic lines; nonspatial data recorded in standalone tables such as a description of map units, glossary, data source reference, geomaterials dictionary, and their entities and attributes. Data source references include web links to published standards, data dictionaries, and any other referenced data within the published map. There is a final nonspatial table that is in reference to the original digitized and identified geologic structures per the legacy map plate, these structures were broken up by state (Arizona, Colorado, New Mexico, and Utah) with each structure given a numerical value (starting at 1, for each individual state) these structures were compiled into a synchronous excel document to provide a digital record of those structures and features listed on the legacy map plate.

This digital dataset release of the Tectonic Map of the Colorado Plateau is a courtesy publication of the previously published legacy report by V.C. Kelley in 1955. The original publication, "Tectonic Map of the Colorado Plateau Showing Uranium Deposits" contains elevation contours from the top of the Chinle formation in 1000 ft intervals and geologic structural formations such as monoclinal, synclinal, and anticlinal structures. The digitizing of this map is to provide a more accessible dataset to be available for public usage. The original dataset was in relation to a larger project by the University of New Mexico and their publications in geology of uranium distributions throughout the Colorado Plateau (Kelley, V.C., 1955, Regional tectonics of the Colorado Plateau and relationship to the origin and distribution of uranium: Albuquerque, University of New Mexico, Publications in Geology no. 5, 120 p., 1 sheet, scale 1:1,000,000.). The entirety of this dataset includes both spatial and non-spatial data held in a singular, GeMS compliant geodatabase. This geodatabase includes a geologic map feature dataset holding fault lines, iso value lines, structure contours, and other geologic lines; nonspatial data recorded in standalone tables such as a description of map units, glossary, data source reference, geomaterials dictionary, and their entities and attributes. Data source references include web links to published standards, data dictionaries, and any other referenced data within the published map. There is a final nonspatial table that is in reference to the original digitized and identified geologic structures per the legacy map plate, these structures were broken up by state (Arizona, Colorado, New Mexico, and Utah) with each structure given a numerical value (starting at 1, for each individual state) these structures were compiled into a synchronous excel document to provide a digital record of those structures and features listed on the legacy map plate.

The Upper Colorado River Basin has a drainage area of about 113,500 square miles in western Colorado, eastern Utah, southwestern Wyoming, northeastern Arizona, and northwestern New Mexico. In the 1980’s and 1990’s, the Upper Colorado River Basin was a study area under of the U.S. Geological Survey's Regional Aquifer-System Analysis (RASA) program (Sun and Johnston, 1994; Sun and Weeks, 1991). The objectives of the RASA program for the Upper Colorado River Basin were to provide regional assessments of major aquifer systems by providing quantitative assessments of the occurrence, movement, and availability of water stored in rock formations that underlie the basin/watershed. These assessments included: (1) the classification of stratigraphic sequences into those intervals that constitute aquifers and those that constitute confining beds; and (2) the generation of maps that portrayed the areal extent of aquifers, aquifer thickness, and overburden thickness. These studies generated a large body of subsurface geologic information as part of the regional aquifer analyses, some of which are captured in this digital data release. Aquifer systems in consolidated rocks in the Upper Colorado River Basin have been grouped into three major subdivisions of sedimentary rocks; in descending order: (1) Tertiary-rock aquifers, (2) Mesozoic-rock aquifers, and (3) Paleozoic-rock aquifers (Taylor and others, 1983; 1986). Within each aquifer group, rocks are further divided into aquifers and confining units on the basis of lithology, depositional environment, and hydrologic characteristics (Glover and others, 1998; Freethy and Cordy, 1991; Geldon, 2003). In a report describing consolidated-rock aquifers of Paleozoic age, 7 hydrostratigraphic units were defined, four aquifers and three confining units (Geldon, 2003). The hydrostratigraphic units of Paleozoic age are locally exposed around the margins of uplifts and in deeply-incised canyon; they occur widely in the subsurface of the Upper Colorado River Basin study area, except in parts of the Uinta, Wind River, and Uncompahgre uplifts where they have been removed by erosion. These hydrostratigraphic units are part of the stratigraphic sequence of Paleozoic rocks that has a total thickness of more than 5,000 ft. This digital dataset contains spatial datasets corresponding to the contoured subsurface maps of Paleozoic rock units produced by the U.S. Geological Survey's Regional Aquifer-System Analysis (RASA) of the Upper Colorado River Basin (Geldon, 2003). The data define the thickness, extent, nomenclature, and facies characteristics of principal hydrostratigraphic units of Paleozoic age in the basin. The digital data describe the following hydrostratigraphic units: the Flathead aquifer, the Gros Ventre confining unit, the Bighorn aquifer, the Elbert-Parting confining unit, the Madison aquifer (consisting of two zones, the Redwall-Leadville zone, and the Darwin-Humbug zone), the Four Corners confining unit (consisting of the Belden-Molas subunit and the Paradox-Eagle Valley subunit), and the Canyonlands aquifer (consisting of three zones, the Cutler-Maroon zone, the Weber-de Chelly zone, and the Park City-State Bridge zone). Contoured thickness and lithology data for each unit are contained in line features classes within a geodatabase; unit extents, facies extents, and formation nomenclatural extents are represented as polygon feature classes. Both types of data are also saved as individual shapefiles. Nonspatial tables define the data sources used, terminology, and the stacking hierarchy and component geologic formations of each the of hydrostratigraphic units

The Upper Colorado River Basin has a drainage area of about 113,500 square miles in western Colorado, eastern Utah, southwestern Wyoming, northeastern Arizona, and northwestern New Mexico. In the 1980’s and 1990’s, the Upper Colorado River Basin was a study area under of the U.S. Geological Survey's Regional Aquifer-System Analysis (RASA) program (Sun and Johnston, 1994; Sun and Weeks, 1991). The objectives of the RASA program for the Upper Colorado River Basin were to provide regional assessments of major aquifer systems by providing quantitative assessments of the occurrence, movement, and availability of water stored in rock formations that underlie the basin/watershed. These assessments included: (1) the classification of stratigraphic sequences into those intervals that constitute aquifers and those that constitute confining beds; and (2) the generation of maps that portrayed the areal extent of aquifers, aquifer thickness, and overburden thickness. These studies generated a large body of subsurface geologic information as part of the regional aquifer analyses, some of which are captured in this digital data release. Aquifer systems in consolidated rocks in the Upper Colorado River Basin have been grouped into three major subdivisions of sedimentary rocks; in descending order: (1) Tertiary-rock aquifers, (2) Mesozoic-rock aquifers, and (3) Paleozoic-rock aquifers (Taylor and others, 1983; 1986). Within each aquifer group, rocks are further divided into aquifers and confining units on the basis of lithology, depositional environment, and hydrologic characteristics (Glover and others, 1998; Freethy and Cordy, 1991; Geldon, 2003). In a report describing consolidated-rock aquifers of Paleozoic age, 7 hydrostratigraphic units were defined, four aquifers and three confining units (Geldon, 2003). The hydrostratigraphic units of Paleozoic age are locally exposed around the margins of uplifts and in deeply-incised canyon; they occur widely in the subsurface of the Upper Colorado River Basin study area, except in parts of the Uinta, Wind River, and Uncompahgre uplifts where they have been removed by erosion. These hydrostratigraphic units are part of the stratigraphic sequence of Paleozoic rocks that has a total thickness of more than 5,000 ft. This digital dataset contains spatial datasets corresponding to the contoured subsurface maps of Paleozoic rock units produced by the U.S. Geological Survey's Regional Aquifer-System Analysis (RASA) of the Upper Colorado River Basin (Geldon, 2003). The data define the thickness, extent, nomenclature, and facies characteristics of principal hydrostratigraphic units of Paleozoic age in the basin. The digital data describe the following hydrostratigraphic units: the Flathead aquifer, the Gros Ventre confining unit, the Bighorn aquifer, the Elbert-Parting confining unit, the Madison aquifer (consisting of two zones, the Redwall-Leadville zone, and the Darwin-Humbug zone), the Four Corners confining unit (consisting of the Belden-Molas subunit and the Paradox-Eagle Valley subunit), and the Canyonlands aquifer (consisting of three zones, the Cutler-Maroon zone, the Weber-de Chelly zone, and the Park City-State Bridge zone). Contoured thickness and lithology data for each unit are contained in line features classes within a geodatabase; unit extents, facies extents, and formation nomenclatural extents are represented as polygon feature classes. Both types of data are also saved as individual shapefiles. Nonspatial tables define the data sources used, terminology, and the stacking hierarchy and component geologic formations of each the of hydrostratigraphic units

The top of the Upper Cretaceous Dakota Sandstone is present in the subsurface throughout the Uinta and Piceance basins of UT and CO and is easily recognized in the subsurface from geophysical well logs. This digital data release captures in digital form the results of two previously published contoured subsurface maps that were constructed on the top of Dakota Sandstone datum; one of the studies also included a map constructed on the top of the overlying Mancos Shale. A structure contour map of the top of the Dakota Sandstone was constructed as part of a U.S. Geological Survey Petroleum Systems and Geologic Assessment of Oil and Gas in the Uinta-Piceance Province, Utah and Colorado (Roberts, 2003). This surface, constructed using data from oil and gas wells, from digital geologic maps of Utah and Colorado, and from thicknesses of overlying stratigraphic units, depicts the overall configuration of major structural trends of the present-day Uinta and Piceance basins and was used to define the elevation of the base of a specific source-rock interval as part of the assessment. A second structure contour map of the top of the Dakota Sandstone, along with a contoured map showing the elevation of the top of the overlying Mancos Shale, was constructed from well data as part of a stratigraphic research thesis of the Douglas Creek Arch, a structural high which separates the Uinta and Piceance basins (Kuzniak, 2009). This digital dataset contains spatial datasets corresponding to the structure contour maps of the top of the Dakota Sandstone produced by the U.S. Geological Survey's petroleum assessment (Roberts, 2003) and the topical studies along the Douglas Creek Arch (Kuzniak, 2009). Both structure contour maps of the top of the Dakota Sandstone were digitized and attributed as GIS data sets so that these data could be used in digital form as part of U.S. Geological Survey and other studies of these basins. The contours depicting the elevation of the top of the Dakota Sandstone are contained in line feature classes within a geographic information system geodatabase and are also saved as individual shapefiles. Feature classes have a single attribute, elevation, that represents the contoured value. Contoured 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.

The top of the Upper Cretaceous Dakota Sandstone is present in the subsurface throughout the Uinta and Piceance basins of UT and CO and is easily recognized in the subsurface from geophysical well logs. This digital data release captures in digital form the results of two previously published contoured subsurface maps that were constructed on the top of Dakota Sandstone datum; one of the studies also included a map constructed on the top of the overlying Mancos Shale. A structure contour map of the top of the Dakota Sandstone was constructed as part of a U.S. Geological Survey Petroleum Systems and Geologic Assessment of Oil and Gas in the Uinta-Piceance Province, Utah and Colorado (Roberts, 2003). This surface, constructed using data from oil and gas wells, from digital geologic maps of Utah and Colorado, and from thicknesses of overlying stratigraphic units, depicts the overall configuration of major structural trends of the present-day Uinta and Piceance basins and was used to define the elevation of the base of a specific source-rock interval as part of the assessment. A second structure contour map of the top of the Dakota Sandstone, along with a contoured map showing the elevation of the top of the overlying Mancos Shale, was constructed from well data as part of a stratigraphic research thesis of the Douglas Creek Arch, a structural high which separates the Uinta and Piceance basins (Kuzniak, 2009). This digital dataset contains spatial datasets corresponding to the structure contour maps of the top of the Dakota Sandstone produced by the U.S. Geological Survey's petroleum assessment (Roberts, 2003) and the topical studies along the Douglas Creek Arch (Kuzniak, 2009). Both structure contour maps of the top of the Dakota Sandstone were digitized and attributed as GIS data sets so that these data could be used in digital form as part of U.S. Geological Survey and other studies of these basins. The contours depicting the elevation of the top of the Dakota Sandstone are contained in line feature classes within a geographic information system geodatabase and are also saved as individual shapefiles. Feature classes have a single attribute, elevation, that represents the contoured value. Contoured 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 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.