README for U.S. Geological Survey Data Series 961 

Database Compilation for the Geologic Map of the San Francisco Volcanic Field, North-Central Arizona  
By Joseph A. Bard, David W. Ramsey, Edward W. Wolfe, George E. Ulrich, Christopher G. Newhall, Richard B. Moore, Norman G. Bailey, and Richard F. Holm 
2015 
(Database compilation for Miscellaneous Field Studies Maps MF-1956, MF-1957, MF-1958, MF-1959, and MF-1960) 

This digital database was compiled in ArcGIS version 10.1 as a personal geodatabase that contains geologic map feature classes for the geologic map of the San Francisco Volcanic Field, north-central Arizona.  ArcGIS-compatible GIS software is required to use the files of this database.  The geodatabase is delivered in a single zipped folder (161.9 MB in size) in this release for ease of transfer.  The scale of the source mapping limits the usable spatial resolution of the database to 1:50,000 scale or less detailed.  

Available ArcGIS feature classes are described below:

ArcGIS feature class 	Description

geolines 		Contacts between rock units, fault lines offsetting rock units, axes of geologic structures (lines)
geounits 		Rock units (polygons)
map_extents 		Original extents of the five previously-published geologic maps in this compilation (polygons)
sample_points 		Locations of collected geochemical and geochronological samples (points)  

Federal Geographic Data Committee (FGDC) metadata are available for each feature class.