Landscape in Layers
At Toadstool Geologic Park, the geologic record becomes visible at 34 million years ago. Then, heavy clouds of ash from Great Basin (Utah and Nevada) volcanoes blanketed the land. An ancient river carved the valley while the landscape changed to a semi-arid plain.
These layered rocks and clays reveal the area's natural history, exposed by the river that once flowed through here. Seasonal floods and volcanic ash reshaped the face of the land, adding new sediments to this floodplain, like new coats of paint. Eventually the layers were exposed as you see them today by the continuing wind and water erosion.
not a toad nor a stool, but... a sandstone block resting on a small pedestal, resembling
Caption: Read the rocks and clays
Distinctive bands in the rocks and clay illustrate geologic processes that occurred millions of years ago. The bottom layers were deposited the earliest, and are the oldest. Colors are best seen in early morning or late afternoon when the sun is not directly overhead.
Erected by US Forest Service, Department of Agriculture.
Topics. This historical marker is listed in these topic lists: Environment • Paleontology.
Location. 42° 51.476′ N, 103° 35.047′ W. Marker is near Crawford, Nebraska, in Sioux County. Marker can be reached from Oglala National Grassland (Forest Road 902) 1.4 miles Toadstool Road. Located in Toadstool Geologic Park and Campground. Touch for map. Marker is in this post office area: Crawford NE 69339, United States of America. Touch for directions.
Other nearby markers. At least 8 other markers are within 15 miles of this marker, measured as the crow flies. Africa in Nebraska (here, next to this marker); Toadstool (here, next to this marker); Grassroots (here, next to this marker); The Innovation of Early Homesteaders (about 400
Credits. This page was last revised on June 11, 2021. It was originally submitted on June 8, 2021, by Connor Olson of Lemmon, South Dakota. This page has been viewed 66 times since then and 19 times this year. Photos: 1, 2. submitted on June 8, 2021, by Connor Olson of Lemmon, South Dakota. • Bill Pfingsten was the editor who published this page.