Readme for U.S. Geological Survey Geologic Investigations 
Series I-2723

This digital database was compiled with ArcInfo version 
7.2.1 and consists of files containing geologic map and 
topographic base data in ArcInfo coverage and grid format. 
ArcInfo-compatible GIS software is therefore required to 
use the files of this database. The database is stored in a 
single zipped folder (lassenpeak.zip) in this release for 
ease of transfer. The scale of the source map limits the 
spatial resolution (scale) of the database to 1:24,000 or 
smaller except in the area of a 1:2,500-scale inset map of 
the Lassen Peak summit area. Available ArcInfo coverages 
and grids are described below:

ArcInfo coverage         Description
or grid

  geo                    Faults, contacts, and rock units 
                           (line, polygon)

  vent                   Volcanic vents (points)

  sumbnd                 Map boundary for 1:2,500 
                           enlargement of  Lassen Peak 
                           Summit area (lines)

  mzgrd                  Manzanita Lake quad topographic 
                           base

  wppgrd                 West Prospect Peak quad 
                           topographic base

  rpgrd                  Reading Peak quad topographic base

  lpgrd                  Lassen Peak quad topographic base

  sumgrd                 Lassen Peak summit 1:2,500 
                           topographic base