This image represents part of a 7.5-minute geologic quadrangle
map produced on Mylar, which was used as part of the printing
process by the U.S. Geological Survey. The Mylar maps contain
all of the geologic information plotted on a topographic base.
In this image, the geologic information is shown as black lines,
and the topographic and cultural information is shown as green
lines. A second set of Mylar maps is produced from these
originals by removing the topographic and cultural features
using a photographic enhancement technique that filters out the
green lines and leaves only the black-line geologic information.
The second set of Mylar maps is then used in Step 2. We are
currently investigating new methods of converting these Mylar
maps utilizing an image classification program.