readme.txt for USGS I-2778 that explains the contents of the two data files This data release contains a digital database that was compiled with ESRI ArcInfo version 7.2.2 and consists of files containing geologic map and topographic base data in ArcInfo coverage format. ArcInfo-compatible GIS software is required to use the files of this database. The database is stored in a single zipped folder (i2778database.zip) in this release for ease of transfer. The zip file contains geology, organized by quadrangle, and all other relevant GIS layers and metadata. The scale of the source map limits the spatial resolution (scale) of the database to 1:63,360. Available ArcInfo coverages are described below: "quad name"-bndry Map boundary for 1:63,360 quad (lines) "quadname"-geo Faults, contacts, and rock units (lines, polygons) isopach Isopachs of the 1912 Novarupta eruption ash fall (lines) samps Locations of rock samples (points) struc Locations of structure samples Locations of rock samples (points) vent Volcanic vents (points) base Katmai Cluster 1:63,360 topographic base (lines) This data release also contain digital photographs of Katmai Cluster with accompanying photograph captions. The photographs are stored in a single zipped file (i2778photos.zip).