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| Close-up view of calcite crystal crusts covering the cavern wall in Jewel Cave. The surface crust of crystals formed after the cavern had formed by dissolution of the Mississippian-age Pahasapa Limestone (also regionally known as the Madison Limestone) that crops out around the Precambrian-age rocks exposed in the core of the Black Hills (Fox, 2004; DeWitt and others, 1989). |
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