13,500 years ago huge continental glaciers up to a mile high decended upon Iowa leaving behind lakes, hills, kettle holes and other features on the landscape.

Devil's Ridge is one of the best places to observe the kame and kettle topography associated with the last glacier, the Wisconsin Glacier.  The Wisconsin Glacier carved a path through Osceola County forming unique geological features such as the lateral moraine, several kames and a kettle-hole at the Devil's Ridge Wildlife Management Area. 

The Ocheyedan Mound was long thought to be  an Indian burial ground.  This was disproved when geologists investigated and found that it is a kame of glacial origin.  Kames are hills and ridges of stratified drift deposited by glaciers at the mouths of  ice tunnels or ice channels as the glaciers retreated.

Devil's Ridge