Surface Bed Rock
Why is some bedrock smoother than others?
Gitchie Manitou means Great Spirit. This state preserve offers a unique look at bedrock because it is right at the surface.
Transcript
[Abby Brown] Have you ever heard of bedrock? It's the uppermost crust of the earth and it's everywhere. Layered on top of bedrock is the softer material like soil, gravel and sand. Here in Iowa, geologists say that in some areas there are hundreds of feet of that softer material. But up here in northwest Iowa, there's some bedrock right at the surface. And it's an amazing sight to see.
(Map marking Lyon County in the northwest corner of the state.)
Gitchie Manitou State Preserve in Larchwood covers 91 acres along the eastern bank of the Big Sioux River. Its name means great spirit or great force of nature. It was a special place for Native Americans.
As you look around or hike, you can almost feel the ancient history here. Patches of native prairies share this preserve with outcroppings of Sioux quartzite containing shades of pink. This bedrock is over 1.6 billion years old. That makes it the oldest surface bedrock in Iowa. Some of the rock surfaces are smooth, meaning they've been weathered by the wind for a very long time. Bedrock is different in different parts of our state, but here in Gitchie Manitou State Preserve it's out in the open for visitors to admire.
Every county in Iowa has an earthly story to tell. It was an honor visiting these ancient grounds in Lyon County.
Funding for FIND Iowa has been provided by The Coons Foundation, Pella and the Gilchrist Foundation.