In 2019 the U.S. Geological Survey (USGS) quantitively assessed the potential for undiscovered, technically recoverable continuous (unconventional) oil and gas resources in the Niobrara interval of the Cody Shale in the Bighorn Basin Province (Finn and others, 2019). Leading up to the assessment, in 2017, the USGS collected samples from the Niobrara and underlying Sage Breaks intervals (Finn, 2019) to better characterize the source rock potential of the Niobrara interval. Eighty-two samples from 31 wells were collected from the well cuttings collection stored at the USGS Core Research Center in Lakewood, Colorado. The selected wells are located near the outcrop belt along the shallow margins of the basin to obtain samples that were not subjected to the effects of deep burial and subsequent organic carbon loss due to thermal maturation as described by Daly and Edman (1987) (fig. 1). Sixty samples are from the Niobrara interval, and 22 from the Sage Breaks interval (fig. 2).

The Bighorn Basin is a large Laramide structural and sedimentary basin that encompasses about 10,400 square miles in north-central Wyoming and south-central Montana (fig. 1). The basin is bounded on the northeast by the Pryor uplift, on the east by the Bighorn uplift and on the south by the Owl Creek uplift. The northern margin is formed by a zone of faulting and folding referred to as the Nye-Bowler lineament. The western and northwestern margins are formed by the Absaroka volcanics and Beartooth uplift, respectively (fig. 1). Commercial hydrocarbon production was first established in the Bighorn Basin when oil was discovered from Cretaceous reservoirs at Garland field in 1906 (Biggs and Espach, 1960). Since then, many important conventional oil and gas resources have been discovered and produced from reservoirs ranging from Cambrian through Tertiary in age (De Bruin, 1993; Fox and Dolton, 1989,1996). In addition, a potential basin-centered gas accumulation may be present in Cretaceous reservoirs in the deeper parts of the basin (Spencer, 1987; Ryder, 1987; Surdam and others, 1997; Johnson and Finn, 1998; Johnson and others, 1999; and Finn and others, 2010). It has been suggested that various Upper Cretaceous marine shales are the principal hydrocarbon source rocks for many of these accumulations (Geis, 1923; Burtner and Warner, 1984; Hagen and Surdam, 1984; Meissner and others, 1984; Ryder, 1987). With new drilling and well completion technologies, equivalent marine source rock intervals, in particular the Niobrara Formation, are now important continuous (unconventional) shale gas and shale oil objectives in other Rocky Mountain basins (Matthews, 2011; Sonnenberg, 2011; Williams and Lyle, 2011; Durham, 2012a,b, 2013; Taylor and Sonnenberg, 2014; and Hawkins, 2016). In the Bighorn Basin the Niobrara is represented by shales, calcareous shales, marls, siltstones, and sandstones in the lower part of the Upper Cretaceous Cody Shale (Finn, 2014) (fig. 2). Please see supplemental information for associated references. Selected figures have also been included to help describe this data release. These figures are provided in pdf and jpg format. These include: Fig. 1_Rocky Mountain basins.pdf/jpg. Map of Rocky Mountain region showing locations of Laramide sedimentary and structural basins and intervening uplifts. Fig. 2_Xsection.pdf/jpg. Regional east-west stratigraphic cross section of Cretaceous rocks in the Wind River Basin. Each modified from Finn (2014). Please see data dictionary sheet in the excel file for detailed table column/attribute information.

The Bighorn Basin is a large Laramide structural and sedimentary basin that encompasses about 10,400 square miles in north-central Wyoming and south-central Montana (fig. 1). The basin is bounded on the northeast by the Pryor uplift, on the east by the Bighorn uplift and on the south by the Owl Creek uplift. The northern margin is formed by a zone of faulting and folding referred to as the Nye-Bowler lineament. The western and northwestern margins are formed by the Absaroka volcanics and Beartooth uplift, respectively (fig. 1). Commercial hydrocarbon production was first established in the Bighorn Basin when oil was discovered from Cretaceous reservoirs at Garland field in 1906 (Biggs and Espach, 1960). Since then, many important conventional oil and gas resources have been discovered and produced from reservoirs ranging from Cambrian through Tertiary in age (De Bruin, 1993; Fox and Dolton, 1989,1996). In addition, a potential basin-centered gas accumulation may be present in Cretaceous reservoirs in the deeper parts of the basin (Spencer, 1987; Ryder, 1987; Surdam and others, 1997; Johnson and Finn, 1998; Johnson and others, 1999; and Finn and others, 2010). It has been suggested that various Upper Cretaceous marine shales are the principal hydrocarbon source rocks for many of these accumulations (Geis, 1923; Burtner and Warner, 1984; Hagen and Surdam, 1984; Meissner and others, 1984; Ryder, 1987). With new drilling and well completion technologies, equivalent marine source rock intervals, in particular the Niobrara Formation, are now important continuous (unconventional) shale gas and shale oil objectives in other Rocky Mountain basins (Matthews, 2011; Sonnenberg, 2011; Williams and Lyle, 2011; Durham, 2012a,b, 2013; Taylor and Sonnenberg, 2014; and Hawkins, 2016). In the Bighorn Basin the Niobrara is represented by shales, calcareous shales, marls, siltstones, and sandstones in the lower part of the Upper Cretaceous Cody Shale (Finn, 2014) (fig. 2). Please see supplemental information for associated references. Selected figures have also been included to help describe this data release. These figures are provided in pdf and jpg format. These include: Fig. 1_Rocky Mountain basins.pdf/jpg. Map of Rocky Mountain region showing locations of Laramide sedimentary and structural basins and intervening uplifts. Fig. 2_Xsection.pdf/jpg. Regional east-west stratigraphic cross section of Cretaceous rocks in the Wind River Basin. Each modified from Finn (2014). Please see data dictionary sheet in the excel file for detailed table column/attribute information.

In 2021 the United States Geological Survey (USGS) sampled the lower part of the Upper Cretaceous Lewis Shale in the eastern part of the Southwestern Wyoming Province to better characterize its petroleum source rock potential for an upcoming resource assessment. Ninety-five samples from 24 wells were collected from well cuttings of the lower part of the Lewis Shale stored at the U.S. Geological Survey Core Research Center in Lakewood, Colorado. The selected wells are located near the shallow margins of the basin to obtain samples that were not subjected to the effects of deep burial and subsequent organic carbon loss due to thermal maturation as described by Daly and Edman (1987) (fig, 1). The sample intervals were selected based on high gamma ray responses that Pyles and Slatt (2007) interpreted to be organic-rich condensed sections. Special emphasis was given to the Asquith marker bed which represents the maximum transgression of the Lewis Shale (Pasternack, 2005) (fig. 2).

In 2021 the United States Geological Survey (USGS) sampled the lower part of the Upper Cretaceous Lewis Shale in the eastern part of the Southwestern Wyoming Province to better characterize its petroleum source rock potential for an upcoming resource assessment. Ninety-five samples from 24 wells were collected from well cuttings of the lower part of the Lewis Shale stored at the U.S. Geological Survey Core Research Center in Lakewood, Colorado. The selected wells are located near the shallow margins of the basin to obtain samples that were not subjected to the effects of deep burial and subsequent organic carbon loss due to thermal maturation as described by Daly and Edman (1987) (fig, 1). The sample intervals were selected based on high gamma ray responses that Pyles and Slatt (2007) interpreted to be organic-rich condensed sections. Special emphasis was given to the Asquith marker bed which represents the maximum transgression of the Lewis Shale (Pasternack, 2005) (fig. 2).

The Wind River Basin is a large Laramide (Late Cretaceous through Eocene) structural and sedimentary basin that encompasses about 7,400 square miles in central Wyoming (fig. 1). The basin is bounded by the Washakie Range and Owl Creek and southern Bighorn Mountains on the north, the Casper arch on the east, the Granite Mountains on the south, and Wind River Range on the west (figs. 1). Many important conventional and unconventional oil and gas resources have been discovered and produced from reservoirs ranging from Mississippian through Tertiary in age (Keefer, 1969; Fox and Dolton, 1989, 1996; De Bruin, 1993; Johnson and others, 1996, 2007). It has been suggested by numerous authors including: Keefer, 1969; Meissner and others, 1984; Fox and Dolton, 1989, 1996; Johnson and Rice, 1993; Nuccio and others, 1996; and Schelling and Wavrek, 1999, 2001: that various Upper Cretaceous marine shales are the principal hydrocarbon source rocks for many of these accumulations. With new drilling and well completion technologies, equivalent marine source rock intervals, in particular the Niobrara Formation, are now important continuous (unconventional) shale gas and shale oil objectives in other Rocky Mountain basins ((Matthews, 2011; Sonnenberg, 2011; Williams and Lyle, 2011; Durham, 2012a,b, 2013; Taylor and Sonnenberg, 2014; and Hawkins, 2016). In the Wind River Basin the Niobrara is represented by shales, calcareous shales, marls, siltstones, and sandstones in the lower shaly member of the Upper Cretaceous Cody Shale (Finn, 2017) (fig. 2). Please see supplemental information for associated references. Selected figures have also been included to help describe this data release. These figures are provided in pdf and jpg format. These include: Fig. 1_Rocky Mountain basins.pdf/jpg. Map of Rocky Mountain region showing locations of Laramide sedimentary and structural basins and intervening uplifts. Fig. 2_Regional Cretaceous X section.pdf/jpg. Regional east-west stratigraphic cross section of Cretaceous rocks in the Wind River Basin. Each modified from Finn (2017).

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

In 2024, the United States Geological Survey (USGS) compiled rock properties data from the USGS Core Research Center's (CRC) database for the Southwestern Wyoming Province and adjoining areas to better characterize the potential hydrocarbon sources and reservoirs in the area. Data from 53 wells were collected from data analysis results located in the CRC database. These data are derived from a combination of USGS and non-USGS laboratory analyses, with samples provided over several decades by researchers who accessed the CRC collection. The compiled data are from pre-Cretaceous Formations in the Southwestern Wyoming Province area. For each well, accompanying metadata details the sample sources, analytical methods, and quality considerations to aid in scientific analysis and public use.

This data release contains geochemical and mineralogical laboratory results from core samples collected from the USGS Cow Creek 1-21 well. The well was drilled and cored in 2022 and targeted the Lewis Shale on the eastern edge of the Washakie Basin in Carbon County, Wyoming. The core data include results from total organic carbon (TOC) and total carbon (TC) analysis, programmed pyrolysis, inductively coupled plasma-optical emission spectroscopy and mass spectrometry (ICP-OES/MS), X-ray diffraction (XRD), stable isotope (C-13) analysis, and vitrinite reflectance analysis. A separate data release contains 4 geophysical wire line logs and is available at .