Snail (Helix leidyi) on pedestal.
The position of this fossil demonstrates how erosion and "settling" work to concentrate fossils in the Badlands. Rain water washing over the ground in sheet flow has enough energy to carry away the fine silt and clay matrix surrounding the fossils but not the larger and heavier fossils. The fossils therefore "settle" as the matrix is removed from around and beneath them and end up concentrating on the slower eroding flats. Badlands National Park.
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All images ©1999 Daniel Moore