1994. King, Philip B., Arndt, Raymond E., Schruben, Paul G., Bawiec, Walter J., and Beikman, Helen M. This polygon shapefile shows the boundaries of geologic units within the United States. This layer is part of the Geologic Map of the United States... Geological Survey (U.S.).
2005. Geological Survey (U.S.). This map layer contains locations and information on faults and associated folds, in the United States, that are believed to be sources of signific... National Atlas of the United States.