http://pubs.usgs.gov/sim/3268/README.txt

Version 1.1, March, 2014
  - Minor edits were made to the geodatabase to correct geology
    and facilitate edgematch with adjacent USGS maps.
  - The database was upgraded from ArcGIS 9.3 to ArcGIS 10.2.
  - Changes made to the geodatabase are not reflected in the
    pamphlet or on map sheet PDFs.

U.S. Geological Survey Scientific Investigations Map SIM-3268
Geologic Map of the Glen Canyon Dam 30' x 60' Quadrangle,
Coconino County, Northern Arizona

Description of digital dataset files posted on this website:

README.txt - this file

SIM3268_metadata.txt - FGDC compliant metadata. Each geodatabase
  feature class also has its own metadata.

glca_db.zip - zipped package of files necessary to create an
ArcMap Personal Geodatabase project.
     -- readme_glca_db.txt
     -- glencanyon100k_v1.1.mdb - ArcGIS Personal Geodatabase
     -- glencanyon100k.style - ArcMap style for symbolizing data
     -- f36111e1.tif - 1:100,000-scale DRG base

glca_shape.zip - zipped package of Feature Classes converted to
shapefiles to facilitate use of the data in ArcMap and other
applications.
     -- readme_glca_shape.txt
     -- glca_shapefiles_v1.1 - Shapefiles folder
     -- glencanyon100k.style - ArcMap style for symbolizing data
     -- f36111e1.tif - 1:100,000-scale DRG base