Developed by the Association of American State Geologists (AASG) and the United States Geological Survey (USGS), the National Geologic Map Database (NGMD) is a data portal designed to provide a mapped overview of geologic spatial data and to provide a pointer to users on the source data. 

• National-scale bedrock and surficial maps, and four state-scale maps
• a Dynamic Legend that shows only the map units within the field of view
• a new Geologic Materials classification, designed to help the layman by bringing these maps into a unified view, using simple terms and definitions
• a simplified back-end database whose design and science terminologies are related to the new “NCGMP09″ design
• integration with other NGMDB databases (Map Catalog and Geolex) that provides users with information about the geologic units and source maps
• links to the source maps and related Web-mapping systems, in the state geological surveys.