Digital Geologic Map of Sherman Quadrangle, North-Central Texas

This data set was created for use in a regional ground-water model of the Lake
Texoma watershed for a project by the U.S. Environmental Protection Agency,
National Risk Management Research Laboratory located in Ada, Oklahoma, titled
"Development of protocols and decision support tools for assessing watershed
system assimilative capacity, in support of risked-based ecosystem management
and restoration practices."

Although this data set was created for use in a specific project, it may be
used to make geologic maps, and determine approximate areas and locations of
various geologic units.

This digital data set contains geologic formations for the 1:250,000-scale
Sherman quadrangle, Texas and Oklahoma. The original data are from the Bureau
of Economic Geology publication, "Geologic Atlas of Texas, Sherman sheet", by
J.H. McGowen, T.F. Hentz, D.E. Owen, M.K. Pieper, C.A. Shelby, and V.E. Barnes,
1967, revised 1991.

Additional geology data sets are available for Oklahoma at URL
"http://ok.water.usgs.gov/gis/geology/index.html". The source maps for three
counties in the Oklahoma panhandle are at a scale of 1:125,000. The source maps
for the rest of Oklahoma are at a scale of 1:250,000.

The original geology source map was published in the Transverse Mercator
Projection, Zone 14. This data set was projected to an Albers Equal Area
projection (Synder, 1987), cast on the North American Datum of 1983.

This electronic report was subjected to the same review standard that applies
to all U.S. Geological Survey reports. Reviewers were asked to check the
topological consistency, tolerances, attribute frequencies and statistics,
projection, and geographic extent. Reviewers were given digital data sets and
paper plots for checking against the source maps to verify the linework and
attributes. The reviewers were asked to check the metadata and accompanying
files for completeness and accuracy.