What are digitally vectorized geologic quadrangle maps (DVGQs), and how do they differ from scanned images?
The citizens of Kentucky are fortunate that the entire state is mapped geologically at the detailed scale of 1:24,000. The 707 paper maps were first published in cooperation with the U.S. Geological Survey as part of the GQ series. The same maps will now be available in two computerized formats. The first format is scanned, georeferenced images of the original paper maps. These data are exact facsimiles of the GQ maps, and because they are georeferenced, they can be compared to other spatially referenced data from KGS or other sources. The scanned images cannot be edited or queried in the same way that a vectorized database can, however. They can be downloaded at no cost from the Kentucky Infrastructure Authority’s Web site (kymartian.state.ky.us/gqmaps/).
The second computerized format is digitally vectorized geologic quadrangles (or DVGQ’s). The DVGQ’s are databases of geologic information adapted from the original geologic maps. The data sets represent geologic features as vector points, lines, or areas; characteristics and descriptions of the features are also provided. Geologic maps are complex documents that contain various kinds of information that relate to the age, composition, and structure of rock units occurring at the earth’s surface. Geologic maps also contain locations and descriptions of economic and mineral features. Because of this complexity, the information cannot be stored as a single data structure; rather, individual themes have been created to represent different kinds of geologic features. This document describes the DVGQ database and how to use it.