http://pubs.usgs.gov/sim/3108/hrv_readme.txt

  Description of digital dataset files posted on this 
  website:

  hrv_readme.txt - this file

  hrv_metadata.txt - FGDC compliant upper level metadata. 
  Feature dataset, feature classes and list of map units 
  (lmu) table also have their own metadata.

  hrv_db.zip - zipped package of files necessary to create 
  an ArcMap Personal Geodatabase project.
      -- readme_hrv_db.txt
      -- hrv_mdb.zip - Personal geodatabase
      -- hrv24k.style - ArcMap style for symbolizing data
      -- hrv_base.zip - zipped 1:100,000-scale DRG base

  hrv_shape.zip - zipped package of feature classes 
  converted to shapefiles to facilitate use of the data in 
  ArcMap and other applications.
      -- readme_hrv_shape.txt
      -- hrv24k.style - ArcMap style for symbolizing data
      -- hrv_base.zip - zipped 1:100,000-scale DRG base
      -- Shapefiles include:
        -- hrv_arc.shp - geologic contacts and faults
        -- hrv_atd.shp - bedding, fault offsets and joints
        -- hrv_fld.shp - fold axes
        -- hrv_gln.shp - fractures
        -- hrv_kar.shp - karst features
        -- hrv_min.shp - mines
        -- hrv_poly.shp - geologic unit polygons
        -- hrv_pt.shp - geologic unit points