Virtual Silurian Reef - Prereef Rock - Grafton, Wisconsin

Silurian Reef at Grafton, Wisconsin

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Prereef deposits consist of coarse-grained dolostone composed of visible dolomite crystals, fossil shell debris, and fewer whole shells. This rock represents an original sediment of carbonate sand. The rock shows extensive cross-bedding, a feature that indicates a shallow seafloor on which sediment particles were moved frequently by waves and currents.



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