Circular-shaped depressions at the summit of a volcanic core or on the surface of the land caused by the impact of a meteorite; man-made depressions caused by an explosion. [USGS GNIS Feature Class Definitions <>]
This category is also used for calderas.
Alexandria Digital Library Feature Type Thesaurus
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Geologic Map of the Tularosa Mountains 30´ × 60´ Quadrangle, Catron County, New Mexico

This digital map database was compiled from previously published and unpublished data by the author and USGS colleagues, and from published maps by others, as indicated in figure 3 on the map sheet. A pamphlet included with the map provides a brief discu

Generalized Geologic Map of the Upper Animas River Watershed and Vicinity, Silverton, Colorado

This dataset represents geology compiled for the upper Animas River Watershed near Silverton, Colorado. The source data used are derived from 1:24,000, 1:20,000, 1:48,000 and 1:250,000-scale geologic maps by geologists who have worked in this area since

Digital Geologic Map of the Nevada Test Site and Vicinity, Nye, Lincoln, and Clark Counties, Nevada, and Inyo County, California

This digital geologic map of the Nevada Test Site (NTS) and vicinity, as well as its accompanying digital geophysical maps, are compiled at 1:100,000 scale. The map compilation presents new polygon (geologic map unit contacts), line (fault, fold axis, me