Geologic and structure map of the Choteau 1 x 2 degree quadrangle, western Montana: a digital database.

This dataset was developed to provide geologic map GIS of the Choteau
1:250,000 quadrangle for use in future spatial analysis by a variety of users.
These data can be printed in a variety of ways to display various geologic
features or used for digital analysis and modeling. This database is not meant
to be used or displayed at any scale larger than 1:250,000 (e.g. 1:100,000 or
1:24,000).

The geologic and structure map of Choteau 1 x 2 degree quadrangle (Mudge and
others, 1982) was originally converted to a digital format by Jeff Silkwood
(U.S. Forest Service and completed by the U.S. Geological Survey staff and
contractor at the Spokane Field Office (WA) in 2000 for input into a geographic
information system (GIS). The resulting digital geologic map (GIS) database
can be queried in many ways to produce a variey of geologic maps. Digital base
map data files (topography, roads, towns, rivers and lakes, etc.) are not
included: they may be obtained from a variety of commercial and government
sources. This database is not meant to be used or displayed at any scale
larger than 1:250,000 (e.g. 1:100,000 or 1:24,000. The digital geologic map
graphics and plot files (chot250k.gra/.hp/.eps and chot-map.pdf) that are
provided in the digital package are representations of the digital database.
They are not designed to be cartographic products.

This GIS consists of two major Arc/Info datasets, a line and polygon file
(chot250k) containing geologic contact and structures (lines) and geologic map
rock units (polygons), and a point file (chot250kp) containing structural point
data for plunging folds.