Geologic Map Database of the Washington DC Area Featuring Data From Three 30' X 60' Quadrangles: Frederick, Washington West, and Fredericksburg, USGS OFR 01-227

Geology was researched and compiled for use in studies of ecosystem health,
environmental impact, soils, groundwater, land use, tectonics, crustal genesis,
sedimentary provenance, and any others that could benefit from geographically
referenced geological data.

The Washington DC Area geologic map database (DCDB) provides geologic map
information of areas to the NW, W, and SW of Washington, DC to various
professionals and private citizens who have uses for geologic data. Digital,
geographically referenced, geologic data is more versatile than traditional
hard copy maps, and facilitates the examination of relationships between
numerous aspects of the geology and other types of data such as: land-use data,
vegetation characteristics, surface water flow and chemistry, and various types
of remotely sensed images. The DCDB was created by combining Arc/Info
coverages, designing a Microsoft (MS) Access database, and populating this
database. Proposed improvements to the DCDB include the addition of more
geochemical, structural, and hydrologic data.

Data are provided in several common GIS formats and MS Access database files.
The geologic data themes included are bedrock, surficial, faults and fold axes,
neat line, structural data, and sinkholes; the base themes are political
boundaries, roads, elevation contours, and hydrography.

Data were originally collected in UTM coordinates, zone 18, NAD 1927, and
projected to geographic coordinates (Lat/Long), NAD 1983. The data base is
accompanied by large format color maps, a readme.txt file, and a explanatory
PDF pamphlet.