June 23, 2017
Toadstools are sandstone slabs resting on clay pedestals. They look like mushrooms.
Toadstools are formed when wind and water erode the soft clay under the cap of the toadstool. Sometimes the toadstool stem collapses and caps are left scattered around. 
The picture below shows harder quartzite surrounded by mud.
This park contains not only the toadstool formations but a wealth of fossils and evidence of animals from the Oligocene epoch 30 million years ago.
Fossils of miniature horses, humpless camels, giant tortoises, pigs and rhinoceroses have been found here. The animals left their footprints in soft soils of the ancient broad shallow river that used to flow through this area.
We were struck by the beauty of other rocks in the park.
We ate our picnic lunch here by a reproduction sod house built in 1984.
2 Comments
Laura · July 18, 2017 at 11:14 am
The sky is awesomely blue. Ever any clouds? I am so enjoying my history lessons. Thanks.
Jane Appel · July 18, 2017 at 1:33 pm
Thank you for your comments! In Nebraska the sky is ALWAYS blue [in our experience]. Not so much in South Dakota but approaching storms make for striking photos sometimes. Stay tuned. We’re working on new posts.