From: Sam Wormley 
Newsgroups: sci.geo.satellite-nav
Subject: USGS: DRGs On-Line (It's a beginning)
Date: 9 Sep 1998 19:33:27 GMT
Organization: Iowa State University
Message-ID: <6t6l67$v2o$3@news.iastate.edu>

Ref: ftp://ftp.emtc.usgs.gov/pub/gis_data/
     ftp://ftp.emtc.usgs.gov/pub/gis_data/drg_data/

11/27/96

ftp.emtc.nbs.gov:/pub/gis_data directory structure
Please read the index files in the directories.

         |-100k_sections-----------------|-a--|-ada_mn
         |                               |-.  |-.
         |-aerial_photos-umrs-|-alton    |-.  |-.
gis_data-|                    |-.        |-.  |-.
         |                    |-.        |-y  |-ava_mo
         |                    |-.        
         |                    |-starved_rock
         |
         |-graphics--|-example_gifs
         |           |-map_products---|--umrs
         |-metadata                   |--msp_atlas
         |
         |-umrs_floodplain--|-alton
         |                  |-.
         |-gps_basestation  |-.
                            |-.
                            |-starved_rock
                            
100k_sections:
   100k_sections contains GIS data tiled to either 1:100,000-scale 
   or 1:24,000-scale USGS quadrangle boundaries.  Types of data 
   contained within these directories are, USGS DLG data, scanned
   and rectified USGS quadrangle images, and Landsat Thematic Mapper
   data.

aerial_photos:
   Aerial_photos contains scanned images of 1994 1:15,000-scale 
   color infrared aerial photographs of the Upper Mississippi River 
   System's floodplain.
   
graphics:
   Graphics contains two types of data, example .GIF images, and map 
   products.  The example .GIF images are used by the EMTC Web site 
   to provide users with an idea of what the various data sets look 
   like.  The map_products directory currently contains images, 
   ARC/INFO graphic files (.GRA), and acrobat reader files (.PDF) for 
   selected EMTC map products.

metadata:
   Metadata contains the individual coverage's metadata files. 

umrs_floodplain:
   UMRS_floodplain contains GIS data files created for Upper Mississippi
   River System.  Most of the coverages contained within this directory 
   do not contain data for outside the river's floodplain.  Types of
   data contained within this directory are, land cover/land use data,
   aquatic areas, bathymetric data, navigation structures, and habitat
   data.

Note: Some of the files are compressed using the GNU compression utility
"gzip". You will need the GNU utility to uncompress them. The gzip
utilities are available via anonymous ftp from prep.ai.mit.edu:/pub/gnu.

Files with the .gz extension are double precision coverages, compressed 
with the gzip utility.  Files with the .exe extension are single 
precisions coverages, compressed with a PC-based self extracting pkzip 
utility.