Digital geologic map of Lawton quadrangle, southwestern Oklahoma

                             (diskette 2 of 3)



        U.S. Geological Survey Open-File Report 96-376



Directory   / (root) a_readme.1st  file:





                                ABSTRACT



   This diskette contains a digital data set and accompanying

documentation for surficial geology of the 1:250,000-scale Lawton

quadrangle, Oklahoma.  The original data are from the Geologic Map,

sheet 1 of 4, included in the Oklahoma Geological Survey publication,

Reconnaissance of the water resources of the Lawton quadrangle,

southwestern Oklahoma, Hydrologic Atlas 6, Havens, 1977.  The geology

on sheet 1 was compiled by R.O. Fay, 1967-68 and J.S. Havens, 1973.

                                         

                                INTRODUCTION



   This diskette contains a digital data set and accompanying

documentation for surficial geology of the 1:250,000-scale Lawton

quadrangle, Oklahoma.  The original data are from the Geologic Map,

sheet 1 of 4, included in the Oklahoma Geological Survey publication,

Reconnaissance of the water resources of the Lawton quadrangle,

southwestern Oklahoma, Hydrologic Atlas 6, Havens, 1977.  The geology

on sheet 1 was compiled by R.O. Fay, 1967-68 and J.S. Havens, 1973.

                                         

   The data are provided in ARC/INFO export file format (ESRI, 1995).

The use of trade names is for descriptive purposes only, and does not

imply endorsement by the U.S. Government.  ARC/INFO software was used

in the development of the data set, and an ARC/INFO original-format

file is provided for users' convenience.



   All references to file names, directories, and pathnames in this

document are enclosed in quotation marks.  Pathnames use MS-DOS-style

naming conventions, with the "\" character indicating the highest-

level directory of the diskette.  



   Compilation of the data set on this diskette was funded under a

cooperative Joint Funding Agreement between the U.S. Geological Survey

and the State of Oklahoma, Office of the Secretary of Environment.



                            FILE FORMATS



   The data set files with ".gz" extensions were compressed for

distribution on the diskette.  The data are in ARC/INFO export file

format.  These files need to be uncompressed to access the digital

data. The file "\gzip\gunzip.exe" is an MS-DOS executable program

included on diskette 3 of 3 that will uncompress the data files. To

uncompress a file, type "gunzip -a" and the file name. Then the file

should be renamed to its original name.  For example:



gunzip -a geology.gz

rename geology geology.e00



Table 1 shows the uncompressed file characteristics.



Table 1.  Uncompressed file characteristics.

---------------------------------------------------------------------- 

File name       Original     Uncompressed    Uncompressed

                file name    DOS file size   UNIX file size

                             in bytes        in bytes

----------------------------------------------------------------------

geology.gz      geology.e00  4,253,068       4,177,724





   A graphic image of the data sets on both diskettes is provided in a

Graphics Interchange Format (GIF) file and has a file extension of

".gif".  The GIF file can be easily displayed on a variety of computer

systems using readily available display software.  This image provides

a simplified view of the data sets, and may be used for browsing

purposes.  The GIF file portrays significantly less spatial resolution

and information content than the actual data sets.



                           DISKETTE ORGANIZATION



   The diskette is compatible with the MS-DOS operating system.  File

names with extensions of ".gz", and ".gif" are binary-format files.

Other files are ASCII format files.  All ASCII files use MS-DOS record

delimiters (carriage return, line feed) to indicate the end of lines.

Conversion of record delimiters in these ASCII files may be necessary

for use with operating systems other than MS-DOS.  A utility such as

DOS2UNIX, the FTP file transfer utility, or a text editor may be used

to convert the record delimiters.  Unix users may use the following

perl script to convert the record delimiters:



#!/usr/bin/perl -pi.dosbak

s/\r\n$/\n/;





   This diskette is organized into five files:



\-------|-a_readme.1st  - This file

        |-a_notice.txt  - Liability disclaimer

        |-geology.gz    - Geology data set in ARC/INFO export file

        |                 format

        |-geology.fgd   - Complete documentation of the sources

        |                 and procedures used to create the geology

        |                 data set

        |-browse.gif    - Browse image of the data sets in GIF format



                         DATA-SET DOCUMENTATION

     

   A documentation file (known as metadata) for the data set has the

file extension of ".fgd".  The documentation file complies with the

Federal Geographic Data Committee (FGDC) Content Standards for Digital

Geospatial Metadata (Federal Geographic Data Committee, 1994).  The

FGDC-compliant metadata file contains detailed descriptions of the

data set, and includes narrative sections describing the procedures

used to produce the data set in digital form.



   The ARC/INFO version of the data contains the documentation

information used to create the FGDC-compliant metadata file.  The

DOCUMENT program, an ARC Macro Language program, jointly developed by

the U.S. Geological Survey, the U.S. Environmental Protection Agency,

and Environmental Systems Research Institute, may be used to display,

reference, or update the data documentation file (Nebert, 1994).  The

DOCUMENT program works with ARC/INFO revisions 7.0.2 and 7.0.3.

Although the FGDC-compliant metadata file is intended to document the

ARC/INFO-format data set, the DOCUMENT program produces metadata files

that contain some ARC/INFO-specific terminology.  Users are cautioned

not to be confused by this terminology.  The FGDC-compliant metadata

file should contain enough information to eliminate any confusion

caused by the use of ARC/INFO-specific terminology.



                           GEOMETRIC REGISTRATION



   The Albers Equal Area map projection (Snyder, 1987) is used for the

data set.  This projection is appropriate for maps of the conterminous

United States because of the visual presentation and equal-area

characteristic, which facilitates areal analysis.  This projection

frequently is used for nationwide digital map data sets.  The

projection is cast on the North American Datum of 1983. Table 2

provides map projection information.



This projection slightly distorts shapes and distances (scale) in

order to maintain equal-area properties.  Scale is true along the

standard parallels, which are to the north and south of Oklahoma.

Scale distortion in Oklahoma reaches a maximum of slightly less than

one percent at the northern border of the state (Snyder, 1987.)



------------------------------------------------------------------------------

Table 2.  Albers Equal Area projection parameters



[GRS80, Geodetic Reference System 1980; NAD83, North American Datum 1983]

______________________________________________________________________________



Projection parameters:



   Spheroid                            GRS80

   Datum                               NAD83

   First standard parallel             29 30 00 North

   Second standard parallel            45 30 00 North

   Central meridian                    96 00 00 West

   Latitude of projection origin       23 00 00 North



Coordinate system parameters:



   False easting                       0

   False northing                      0

   Planimetric units of measure        meters

______________________________________________________________________________



                             REFERENCES CITED



Environmental Systems Research Institute, Inc. (ESRI), 1995,

     ARC/INFO Command References, ARC/INFO Version 7.0.3 ArcDoc:

     Redlands, CA.  [online documentation].



Federal Geographic Data Committee, 1994, Content standards for digital

     geospatial metadata (June 8): Federal Geographic Data Committee,

     Washington, D.C., 78 p.



Havens, J.S., 1977, Reconnaissance of the water resources of the             

     Lawton quadrangle, southwestern Oklahoma: Oklahoma Geological

     Survey Hydrologic Atlas 6, scale 1:250,000, 4 sheets.  (Geology

     on sheet 1 compiled by R.O. Fay, 1967-68 and J.S. Havens, 1973.)

                                            

Nebert, D.D., 1994, Design of the distributed spatial data library

     (DSDL) for the Water Resources Division: U.S. Geological Survey

     Open-File Report 94-327, 26 p.



Snyder, J.P., 1987, Map projections--A working manual: U.S. Geological

     Survey Professional Paper 1395, 383 p.



