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 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.

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.

Geospatial datasets were developed to estimate the depth to the top of the Dakota Sandstone in feet below land surface datum within the Ute Mountain Ute Reservation in Colorado. This study was completed by the U.S. Geological Survey (USGS) in cooperation with the Ute Mountain Ute Tribe. One dataset was created for the contours showing the altitude (in feet) of the top of the Dakota Sandstone (shapefile Kd_talt_hand), and a second dataset was created for polygons representing the outcrops of the Dakota Sandstone (shapefile Dakota_outcrop_poly). These two datasets were used in combination with USGS digital elevation models (DEM) to create a dataset for the depth of the top of the Dakota Sandstone below the land surface contoured at a 100-foot interval (shapefile kd_depth_ci100). The kd_depth_ci100 dataset was used to generate a figure showing the generalized depth to the top of the Dakota Sandstone in feet below land surface in Bauch and Arnold (2019).

Geospatial datasets were developed to estimate the depth to the top of the Dakota Sandstone in feet below land surface datum within the Ute Mountain Ute Reservation in Colorado. This study was completed by the U.S. Geological Survey (USGS) in cooperation with the Ute Mountain Ute Tribe. One dataset was created for the contours showing the altitude (in feet) of the top of the Dakota Sandstone (shapefile Kd_talt_hand), and a second dataset was created for polygons representing the outcrops of the Dakota Sandstone (shapefile Dakota_outcrop_poly). These two datasets were used in combination with USGS digital elevation models (DEM) to create a dataset for the depth of the top of the Dakota Sandstone below the land surface contoured at a 100-foot interval (shapefile kd_depth_ci100). The kd_depth_ci100 dataset was used to generate a figure showing the generalized depth to the top of the Dakota Sandstone in feet below land surface in Bauch and Arnold (2019).

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 data release presents subsurface data from multiple geologic units that were part of a previous study of the regional subsurface structural configuration of the Powder River Basin in Wyoming and Montana. The original data within this geodatabase is sourced from an unpublished doctoral dissertation by Jessie Melick at Montana State University (Melick, 2013). Data contained in this release were generated from elevation grids developed by Jessie Melick using 28,000 wells and geophysical well logs penetrating Paleozoic to Mesozoic strata over a 70,000 square-kilometer area designated by the Department of Energy as a realistic locality for geologic carbon sequestration (Melick, 2013). Information included in this release represents a small component of the larger geomodel, which includes rock-property details such as facies analysis, porosity calculations, and net to gross thickness, among others. Well locations, well identification numbers, geophysical logs, and any other non-public data or information used in the creation of this dataset has been explicitly omitted. Data in this release includes elevation point features on the stratigraphic tops of the Mesaverde Group, Frontier Formation, Lakota Formation, Tensleep Formation, Madison Group, and Precambrian basement that were exported from the original horizon grids as points on a 500x500 m grid spacing. This release additionally contains structure contour maps of the tops of these same units; the contours were digitally generated from the point arrays using automated contouring methods within a geographic information system. Characterizing these units in the subsurface is of value, as they have been identified as potential reservoirs for the geologic sequestration of carbon, units of interest for geothermal energy production, may serve as regional groundwater aquifers, and are currently considered productive hydrocarbon reservoirs (Melick, 2013). Formation top points and structure contours were formatted and attributed as GIS data sets for use in digital form as part of U.S. Geological Survey’s ongoing effort to inventory, catalog, and release subsurface geologic data in geospatial form. This effort is part of a broad directive to develop 2D and 3D geologic information at detailed, national, and continental scales. This data approximates, but does not strictly follow the USGS NCGMP GeMS data structure schema for geologic maps.Structure contour lines for each formation are stored within separate “IsoValueLine” feature classes, while formation tops for each formation are stored as point data in separate “MapUnitPoints” feature classes. These are distributed within a geographic information system geodatabase and are also saved as shapefiles. Contour and point data are provided in both feet and meters to maintain consistency with the original publication and for ease of use. Nonspatial tables define the data sources used, define terms used in the dataset, and describe the geologic units referenced herein. A tabular data dictionary describes the entity and attribute information for all attributes of the geospatial data and accompanying nonspatial tables.

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

Post-Eocene (predominantly Pliocene) continental sedimentary rocks of the Sacramento Valley, CA are up to 1,200 m thick beneath the valley. These rocks contain most of the fresh ground water in the valley, forming a key component of the total water budget for the valley. A 1974 study by the U.S. Geological Survey was an early attempt to develop detailed knowledge of the subsurface geology of the Sacramento Valley. The study delineated the configuration of the base post-Eocene continental sedimentary rocks of the Sacramento Valley and mapped the thickness of those deposits. This digital dataset contains spatial datasets corresponding to the contoured base and thickness of the post-Eocene continental sedimentary rocks as mapped by the U.S. Geological Survey's study of the Sacramento Valley. The structure contour and thickness maps 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 the basin.