http://pubs.usgs.gov/imap/i2628/lfreadme.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 Geologic Investigations Series I-2628
Geologic Map of the Littlefield 30' x 60' Quadrangle, Mohave
County, Northwestern Arizona

Description of digital dataset files posted on this website:

lfreadme.txt - this file

lfmeta.txt - FGDC compliant metadata. Each Geodatabase Feature
Class also has its own metadata.

lfdb.zip - zipped package of files necessary to create an ArcMap
Personal Geodatabase project.
    -- dbreadme.txt
    -- littlefield100k_v1.1.mdb - ArcGIS Personal Geodatabase
    -- littlefield100k.style - ArcMap style for symbolizing data
    -- f36113e1.tif - 1:100,000-scale DRG base

I2628_shapefiles.zip - zipped package of Feature Classes converted
to shapefiles to facilitate use of the data in ArcMap and other
applications.
    -- readme_lfshape.txt
    -- lf_shapefiles_v1.1 - shapefiles folder
    -- littlefield100k.style - ArcMap style for symbolizing data
    -- f36113e1.tif - 1:100,000-scale DRG base