This digital Open-File Report (ofr-98-0623) represents version 1.0 of the
geologic map of the Thirsty Canyon NW quadrangle, Nye County, Nevada.  Most of
the files constituting this geologic map database have been archived (bundled)
and compressed into the accompanying file tcnw.tar.gz using the UNIX TAR and
GZIP utilities.  (For software that enables you to uncompress and extract these
files on your Windows or Macintosh computer,
see http://greenwood.cr.usgs.gov/maps/software.html )

Accompanying the tcnw.tar.gz archive file and this Readme.txt file are two
files in Portable Document Format (PDF) that allow for viewing and printing
the map using Adobe Acrobat Reader (v. 4.0 or later).  (Adobe Acrobat Reader
4.0 viewing software is available free from
http://www.adobe.com/prodindex/acrobat/readstep.html ).  File tcnw24k.pdf is
a 1:24,000-scale graphics display of the actual geologic map and accessory
elements.  Accessory map elements displayed in this graphics file are:
(1) correlation of map units diagram, (2) list of map unit symbols and names,
(3) index map showing regional location and geologic setting of quadrangle,
(4) index map showing sources and dates of geologic mapping, and (5)
explanation of map symbols.  File tcnwexpl.pdf is a detailed textual
description of geologic map units and a discussion of deposits, structure,
and geologic history of the map area that can also be displayed using the
Adobe Acrobat viewing software.

The actual geologic map database comprises six component ArcINFO map coverages
that can be accessed after decompressing and unbundling the tcnw.tar.gz file.
These six coverages (tcnwpoly, tcnwflt, tcnwfold, tcnwdike, tcnwcald, and
tcnwatt) are formatted here in Arc EXPORT format (i.e., tcnw*.e00).  The
tcnwpoly coverage contains all contact lines and labelpoints for each of the
map polygons.  The database includes four line coverages that depict faults
(tcnwflt), fold axes (tcnwfold), dikes (tcnwdike), and caldera-wall segments
(tcnwcald).  Faults that are contacts also appear in the tcnwpoly coverage.
The tcnwatt coverage contains points recording site-specific structural
observations and measurements, such as strike and dip of bedding.

To use these various geographic information system (GIS) files included in the
archive, please first run the import.aml file.  To do this you must have this
directory accessible to the ArcINFO program.  The easiest way to do this is to
change directories to this directory first and then type "arc" at the command
prompt to launch the program.  You may then want to type "w" and return to
confirm your directory location.  You may see the text "WARNING:  New location
is not a workspace." returned from the program.  This is because the GIS
coverage files and associated shadeset file (color524.shd) have not yet been
imported.  In order to make it easier to import the data, an import.aml
program is provided.  To run this program, type "import" and return at the
Arc command prompt.  The program will then import all the necessary files.
Next, type "listcoverages" and return to confirm that coverages and shadeset
have been created for all files with the .e00 extension.  Please refer to the
file tcnwmetdat.txt or tcnwmetdat.html for detailed metadata documentation for
the geologic GIS database.

List of files:

Readme
Readme.pdf
color524.shd
import.aml
tcnw24k.pdf
tcnwatt.e00
tcnwcald.e00
tcnwdike.e00
tcnwexpl.pdf
tcnwflt.e00
tcnwfold.e00
tcnwmetdat.html
tcnwmetdat.txt
tcnwpoly.e00