Jungle on a Seabed
A jungle grew here. Before that, a shallow sea covered the land. Both are gone now, but both left evidence of their passing.
The sea's signature is ammonites, baculites, and clams, pearly fossils entombed in a fossil mud called the Pierre Shale. This shale is exposed in the gully below you.
A jungle sprang up after the sea drained away about 65 million years ago. For a long time tree roots broke up the shale, and chemicals from decaying plants produced a yellow soil. About 37 million years ago sediment from the west washed over the jungle.
The jungle rebounded, converting the new sediment into a red soil. Buried by later sediments, both yellow and red soils were fossilized. We call them the Yellow Mounds Paleosol and the Interior Paleosol.
Marker is on Badlands Loop Road (State Highway 240) 0.3 miles east of Conata Road (Road 509), on the right when traveling east.
Courtesy hmdb.org
