Labels:text | map OCR: USGS science for a changing world Maps Showing Geology, Oil and Gas Fields, and Geologic Provinces of South America Compiled by Christopher J. Schenk, 1 Roland J. Viger,1 and Christopher P. Anderson2 1U.S. Geological Survey, Denver, CO 2Contractor to the U.S. Geological Survey, Denver, CO U.S. Department of the Interior Open File Report 97-470D U.S. Geological Survey 1999