Conversion of Geologic Quadrangle Maps to Geologic Coverages
Abstract
Three hundred sixty-eight geologic maps of 7 1/2-minute quadrangles in Tennessee were converted to geographic information system (GIS) coverages. The procedure used was documented and a list was made of the quadrangles included in the coverages. Maps were converted to GIS coverages by making film copies of scribecoats of the maps. The film copies were scanned, vectorized, and written into a generate format. Coverage polygons were tagged with symbols to identify geologic units, and coverage lines were tagged with line types to designate stratigraphic contacts. Geologic coverages available to geographic information system (GIS) users typically have been made from 1 :250,000-scale base maps. Maps at this scale provide insufficient resolution of detail needed for hydrogeologic and other studies of areas that are less than regional in scope. Studies of these smaller areas often require the more detailed information available on maps at a scale of 1:24,000. At present, this need is met by using geologic maps of quadrangles published at a scale of 1:24,000 by the U.S. Geological Survey (USGS) and the Tennessee Division of Geology. However, the use of paper copies of geologic maps to produce derivative maps is inefficient; in contrast, this task is handled quickly and efficiently with GIS technology. Therefore, the USGS, in cooperation with the Tennessee Department of Environment and Conservation, the U.S. Army Corps of Engineers, the Tennessee Valley Authority, and the U.S. Soil Conservation Service, initiated a project during spring 1990, to convert information on the 7 1/2-minute geologic quadragle maps to digital files that can be accessed with different types of GIS software.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1994
- Accession Number
- ADA444935
Entities
People
- Joseph F. Connell
- Reavis L. Mitchell Iii
- William R. Barron Jr.
Organizations
- United States Department of the Interior