DOI: 10.5066/p14x4xx2
title: Data sets associated with the Hydrogeologic Framework of the Upper Cretaceous and Lower Tertiary Aquifer Systems, Williston and Powder River Structural Basins, United States and Canada

description: These data were released prior to the October 1, 2016 effective date for the USGS’s policy dictating the review, approval, and release of scientific data as referenced in USGS Survey Manual Chapter 502.8 Fundamental Science Practices: Review and Approval of Scientific Data for Release.

Note that this data release has been modified from its original version. This data release was originally published on the U.S. Geological Survey (USGS) Water Mission Area NSDI Node (Node) in 2014. The Node has since been deprecated, and in 2023, the data release was revised and the files were moved to Sciencebase, which is a USGS trusted digital repository. In 2023, when this migration of files to Sciencebase occurred, each unit extent and surface file for the Upper Cretaceous and Lower Tertiary aquifer systems was given its own landing page and citation. In 2025, the 2023 version of these data release were modified further. In the 2025 version, the extents, surfaces, and metadata files were consolidated into a main Sciencebase page, three child pages, and one citation. The 2025 Sciencebase’s main landing page contains a shapefile with the extents of the Upper Cretaceous and Lower Tertiary aquifer systems and the southern boundary of deposits of Quaternary age in the Williston and Powder River Structural Basins area. A child page was created for the Upper Cretaceous aquifer, Lower Tertiary aquifer, and the deposits of Quaternary age detailed in the associated publication (SIR2014_5047). The child pages for the Upper Cretaceous and Lower Tertiary aquifer systems provide the extents, thicknesses, and top altitude surfaces of the two aquifers and their subunits. The child page for the deposits of Quaternary age in the glaciated part of the Williston and Powder River Structural Basins area provide the extent and thickness of the deposits. A new master metadata file was compiled for each child page to document all the datasets. Raster datasets of thickness and top altitude are presented in two formats: ASCII and TIFF, in feet. The 2025 version of the data release was created to make the associated spatial data more accessible to the user and to simplify the ScienceBase catalog.

This data release provides outcrop and subcrop extents and rasters of the top altitude and thickness in feet of the Lower Tertiary aquifer and its subunits (Lower Fort Union, Middle Fort Union, Upper Fort Union), the Upper Cretaceous aquifer and its subunits and base (Fox Hills, Lower Hell Creek, Upper Hell Creek, and the basal confining unit), and the extents and thicknesses of deposits of Quaternary age in the glaciated part of the Williston and Powder River structural basins in Montana, South Dakota, North Dakota, Wyoming, and parts of Canada.The shapefiles of potentiometric surface contours and rasters of horizontal hydraulic conductivity, which were developed as part of the original publication (Thamke and others, 2014), are not included in this data release but are available for download from http://dx.doi.org/10.3133/sir20145047.

The abbreviations used in the data set names are listed below:
Structural basins:
1. WB - Williston Basin
2. PRB - Powder River Basin

Aquifer names:
1. LTRTRY - Lower Tertiary Aquifer
2. UPCTCS - Upper Cretaceous Aquifer

Deposits of Quaternary age files:
QTRNRY - Deposits of Quaternary age

Data category:
1. Extents – polygon extent of aquifer or subunit
2. Thick – unit thickness
3. TopAlt – altitude of top surface of unit

For each child item, files were organized by data category (extent, thickness, or top altitude) and compressed into a zip archive. Zip archives were named by the principal aquifer or Quaternary abbreviation and then by the data category for example LTRTRY_TopAlt.zip contains the top altitude raster surfaces for the Lower Tertiary Aquifer.

The following is a list of Digital Object Identifiers (DOI), for the 2023 versions of the data sets. These DOI have been deprecated and superseded by this data release's DOI (doi:10.5066/P14X4XX2): doi:10.5066/P9IDDOQ1, doi:10.5066/P9IILS7S, doi:10.5066/P946VBV2, doi:10.5066/P9VM11PC, doi:10.5066/P92WNH4Z, doi:10.5066/P90O39NP, doi:10.5066/P9AU0US7, doi:10.5066/P95BLCXN, doi:10.5066/P9Y8751J, doi:10.5066/P9B5X3OK, doi:10.5066/P9A2NSK0, doi:10.5066/P9N9KZPO, doi:10.5066/P943JURD, doi:10.5066/P9XCCQK0, doi:10.5066/P9YT4LP1, doi:10.5066/P9O89YZM, doi:10.5066/P91ZYX07, doi:10.5066/P9UWVV9G, doi:10.5066/P9TMK1OR, doi:10.5066/P9T8PTLS, doi:10.5066/P9Q47D2U, doi:10.5066/P9G6MD3G, doi:10.5066/P92B4REF, doi:10.5066/P92MPNQX, doi:10.5066/P9R6XM7V, doi:10.5066/P9DGQ3VZ, doi:10.5066/P9WPATN3, doi:10.5066/P9XZZG9E, doi:10.5066/P97A695Z, doi:10.5066/P9XJN3D6, doi:10.5066/P9F1W7PD, doi:10.5066/P9B5HEAK, doi:10.5066/P914U0YY.