Digital Geologic Map of the Butler Peak 7.5' Quadrangle, San Bernardino County, California

The data set for the Butler Peak quadrangle has been prepared by the Southern
California Areal Mapping Project (SCAMP), a cooperative project sponsored
jointly by the U.S. Geological Survey and the California Division of Mines and
Geology, as part of an ongoing effort to utilize a Geographical Information
System (GIS) format to create a regional digital geologic database for southern
California. This regional database is being developed as a contribution to the
National Geologic Map Data Base of the National Cooperative Geologic Mapping
Program of the USGS. Development of the data set for the Butler Peak quadrangle
has also been supported by the U.S. Forest Service, San Bernardino National
Forest.

The digital geologic map database for the Butler Peak quadrangle has been
created as a general-purpose data set that is applicable to other land-related
investigations in the earth and biological sciences. For example, the U.S.
Forest Service, San Bernardino National Forest, is using the database as part
of a study of an endangered plant species that shows preference for particular
rock type environments. The Butler Peak database is not suitable for
site-specific geologic evaluations at scales greater than 1:24,000 (1 in =
2,000 ft).

This data set maps and describes the geology of the Butler Peak 7.5'
quadrangle, San Bernardino County, California. Created using Environmental
Systems Research Institute's ARC/INFO software, the data base consists of the
following items: (1) a map coverage showing geologic contacts and units,(2) a
scanned topographic base at a scale of 1:24,000, and (3) attribute tables for
geologic units (polygons), contacts (arcs), and site-specific data (points).
In addition, the data set includes the following graphic and text products: (1)
A PostScript graphic plot-file containing the geologic map on a 1:24,000
topographic base accompanied by a Description of Map Units (DMU), a Correlation
of Map Units (CMU), and a key to point and line symbols; (2) PDF files of the
DMU and CMU, and of this Readme, and (3) this metadata file.

The geologic map data base contains original U.S. Geological Survey data
generated by detailed field observation and by interpretation of aerial
photographs. The map was created by transferring lines from the aerial
photographs to a 1:24,000 mylar orthophoto-quadrangle and then to a base-stable
topographic map. This map was then scribed, and a .007 mil, right-reading,
black line clear film made by contact photographic processes.The black line was
scanned and auto-vectorized by Optronics Specialty Company, Northridge, CA.
The non-attributed scan was imported into ARC/INFO, where the database was
built. Within the database, geologic contacts are represented as lines (arcs),
geologic units as polygons, and site-specific data as points. Polygon, arc, and
point attribute tables (.pat, .aat, and .pat, respectively) uniquely identify
each geologic datum and link it to other tables (.rel) that provide more
detailed geologic information.