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Digital Representation of Isopach Maps for Selected Geologic Periods from an Atlas Published by Sloss and Others (1960) (ver. 2.0, July 2026)

Published by U.S. Geological Survey | Department of the Interior | Catalog Last Checked: August 01, 2026 at 04:45 AM | Dataset Last Updated: July 07, 2026 at 12:00 AM
This data release is the update of the U.S. Geological Survey - ScienceBase data release Sharpe and others (2024). Information of hydrogeologic and geologic importance from the book, "Lithofacies Maps: An Atlas of the United States and Southern Canada" (Sloss and others, 1960) detailing geologic periods, including the Cambrian, Ordovician, Silurian, and Devonian were digitized from scanned maps. Isopach contours were captured and, along with Geologic Map of North America (GMNA) information (Garrity and Soller, 2009), were used to interpolate thickness rasters for each period. Additionally, the lithofacies information on each map was also digitized. First release: November, 2024 Revision 2.0: July, 2026 Data from version 1.0 of the data release are available in the original formats as compressed (.zip) geodatabases (.gdb) of geologic period feature classes, including isopach contours, lithofacies, raster interpolation masks, control points, and thickness rasters. A layer file for symbolizing the lithofacies feature classes and the metadata document are also included. Data for version 2.0 of the data release includes, 1) step 3 masks as shapefiles for all geologic periods, available in Sloss_Isopach_Maps_Step3_Masks.zip, and 2) Step 3 thickness rasters as TIFs for all geologic periods, available in Sloss_Isopach_Maps_Step3_Thickness_Rasters.zip. Citations: Sharpe, J.B., Belitz, K., Fleming, B.J., and Donmoyer, S.J., 2024, Digital representation of isopach maps for selected geologic periods from an atlas published by Sloss and others (1960): U.S. Geological Survey data release, https://doi.org/10.5066/P1GFQCQX. Sloss, L.L., Dapples, E.C., and Krumbein, W.C., 1960, Lithofacies Maps: An Atlas of the United States and Southern Canada, John Wiley & Sons, Inc., 108 pages. Garrity, C.P., and Soller, D.R., 2009, Database of the Geologic Map of North America; adapted from the map by J.C. Reed, Jr. and others (2005): U.S. Geological Survey Data Series 424, http://pubs.usgs.gov/ds/424/.

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