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Start Over Place Delaware Resource Type Line data Subject Impact craters
2005. King, Philip B., Arndt, Raymond E., Schruben, Paul G., Bawiec, Walter J., and Beikman, Helen M. This line shapefile shows the outlines of major calderas and impact structures in the United States. A caldera is a large, generally circular depre... Geological Survey (U.S.) and National Atlas of the United States.