As you walk along the Devonian fossil bed here, you will see hundreds of holes carved into the limestone. They have been formed by a unique process. During the winter months when the upper gates of McAlpine dam are wide open, the fossil beds are submerged below rapidly moving water. A small rock harder than the limestone gets whirled around by the current and cuts away at the limestone. Over time, the rock continues to wear away the limestone carving the pothole larger and larger. If you look closely, you will observe that many of the potholes here have a small rock still inside. Or even a geocache.
Note: Access by foot is possible during low water periods, generally August through October. Ground Zero can also be accessed via boat when river conditions allow. Call McAlpine Dam 502-775-5056 and listen to the short recording.
- Foot Access: If the upper dam spillway is open at all, foot access is not possible.
- Boat Access: If the lower gauge is 20 feet or higher, the cache is under water.