GIS Database and Discussion for the Distribution, Composition, and Age of Cenozoic Volcanic Rocks of the Pacific Northwest Volcanic Aquifer System Study Area

by David R. Sherrod and Mackenzie K. Keith

U.S. Geological Survey Open-File Report 2018-1030

2018

This digital database originated as shp files from Open-File Report 2005-1305,
to which additional tabular data were added for age and composition classifications
needed for two-dimensional statistical hydrogeological analysis using fundamental
lithologic criteria. Editing was conducted with ArcGIS 10.2.2.3552 and Mapinfo 12.5.

The final database was exported as shp files for publication.

Two feature classes contain the geologic map data. No topographic bases are provided. The scale of the source map limits the spatial resolution (scale) of the database to 1:500,000 (Idaho, Nevada, Oregon, Utah, Washington) and 1:750,000 (California).

Feature classes and 
Description

NVASA_AgeComp_geo	
Feature class containing the geologic units (polygons)

NVASA_AgeComp_struct	
Feature class containing faults and folds


Also available is an explanatory pamphlet, with illustrations, showing the rationale
and methodology used in the compilation of the newly added tabular data.

Federal Geographic Data Committee (FGDC) metadata are available
for the digital geologic map in text format.