Digital Maps, Data, and GIS

Piece of a digital map showing GIS layers for streams, lakes, state and local roads, 7.5-minute quadrangle boundaries, municipal boundaries, and bedrock geology; all over a 10-meter resolution topographic shaded-relief surface. Location is near Avondale, West Grove 7.5-minute quadrangle, Chester County, Pa.

Geologic maps, topographic maps, aerial photographs, and geospatial data are now being offered in a digital format. The demand is strong for digital geologic and topographic products, particularly georeferenced data that may be used for spatial analysis in Geographic Information Systems (GIS) applications. To meet this demand, the Bureau of Topographic and Geologic Survey is concentrating on creating products in a digital format (including historic work). The basic fieldwork still must be done; however, digital maps and datasets will be the primary means of distributing new products.

Digital Geologic Maps

• Geologic maps in a digital format are included in the list of online publications. Maps in the list of online open-file reports include recent work, and most have associated GIS data files available for downloading.

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