Indian Mound Reserve PrevEnvironmental Features Historic Log HouseNext Geology of the Overhang Overhangs at the Indian Mound Reserve There are several examples of overhangs at the Indian Mound Reserve, but this location, called the Large Overhang, is by far the best to observe this natural process. As water – which is already one of nature’s most powerful forces – flows downstream, it carries with it eroded and loosened sediments which add to it an extra grit.1 As a result, Massie Creek cuts away at the rock bodies on either side of the gorge. However, different rocks erode at different rates and in different ways due to their chemical makeup. Therefore, every rock layer will look a little different as it erodes. Massie Shale erodes very easily. You can actually break it apart between two fingers! This makes it very fragile. As a result, it erodes the most easily and rapidly of the three rock layers. Springfield Dolomite resists erosion much more than Massie Shale can, but is still susceptible to erosion by water as it fractures in a brick-like pattern. Cedarville Dolomite is the strongest against erosion of the three, especially because it does not have a specific fracture pattern. Because of the erosive properties of these three rock layers and their varying levels of resistance against erosion, the result is an upside-down stair-step formation. REFERENCES Illig, A., & Rice, T. (2020). Geologic History of the Overhang at the Indian Mound Reserve. personal. Content developed by Audrey Illig.