20250522 14581200 1.0 TRUE Cooperative National Geologic Map: Precambrian Geology <DIV STYLE="text-align:Left;font-size:12pt"><DIV>The USGS National Cooperative Geologic Mapping Program (NCGMP) was directed by Congress to "bring together detailed national and continental-resolution 2D and 3D information produced throughout the Survey and by federal and state partners" (House Report 116-100), to create a new geologic map of the United States. To fulfill this goal, the NCGMP created a map synthesis engine (Johnstone and others, 2025) based on the Geologic Map Schema (GeMS) standard and used it to bring together and (to some extent) to harmonize source geologic maps originally published by the USGS and by State Geological Surveys. Currently, this map covers the conterminous U.S.; however, work is underway to expand the coverage.The Precambrian geology layer depicts all Precambrian rocks including map units with minimum ages that are younger, such as "Paleozoic to Precambrian" units. The map was composited from all geologic maps that show Precambrian rocks, including where they are mostly buried beneath Phanerozoic sedimentary rocks and inferred from boreholes and geophysical data. In areas covered by maps of both Precambrian outcrops and buried Precambrian basement, the outcropping Precambrian units are preserved instead of the more generalized buried units. Due to the large disparity in scale and degree of interpretation between outcrop maps and subsurface maps, the Precambrian layer is highly discontinuous along source map boundaries. Phanerozoic rocks are included in the map, subdivided into stratified rocks vs. igneous and metamorphic rocks.This layer is one of four created for the new national geologic map. The other layers available are: Earth’s surface (the geology exposed at the Earth’s surface) Quaternary (geologic units of Quaternary age, exposed at the Earth’s surface) Pre-Quaternary (geologic units older than Quaternary, including many "bedrock" geologic maps).Each layer is published by the USGS as GeMS-compliant Esri geodatabases. Those geodatabases are products of the overall geospatial database, which is published as a geopackage. These products and static images of the layers are available from the National Geologic Map Database, at https://ngmdb.usgs.gov/Prodesc/proddesc_118545.htm. For a more performant viewing and data exploration experience for the four layers, please visit the web application at ngmdb.usgs.gov/nationalgeology.</DIV></DIV> This map emphasizes Precambrian geology at both the Earth’s surface and at the buried Precambrian surface. It is part of a new geologic map of the U.S. that is intended as an overview and introduction to the Nation's geology. For a more performant viewing and data exploration experience, please visit the web application at ngmdb.usgs.gov/nationalgeology. For more site-specific information that can inform decision making, please refer to the vast collection of more detailed geologic maps, reports, and data available in the National Geologic Map Database and from State Geological Surveys. <DIV STYLE="text-align:Left;font-size:12pt">Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty.</DIV> USGS NGMDB NGS geology geologic map geologic hazards natural resources