Description: 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 Quaternary layer depicts geologic units of Quaternary age that are exposed at the Earth’s surface in the conterminous United States. Although mostly consisting of unconsolidated materials commonly referred to as "surficial deposits", this layer also includes volcanic rocks of Quaternary age. Also included are all units that may, or are known to, span the Quaternary – Neogene boundary. Where present, units older than Quaternary and map units that are primarily colluvium and/or residuum are categorized as generalized rock and regolith units. In the glaciated regions of the Midwest and Northeast, the map is a composite of 8 state geologic maps depicting Quaternary deposits. In the West and parts of the Southeast, the map is a composite of Quaternary units from 19 state geologic maps depicting geology at the Earth’s surface. The remaining area is populated from 18 regional Quaternary geologic maps produced as part of the USGS Quaternary Atlas series.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) Pre-Quaternary (geologic units older than Quaternary, including many "bedrock" geologic maps) Precambrian (emphasizes Precambrian units at Earth's surface and those depicted in "basement" 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.