When we put in the seawall at Sinclair, they found a chunk of granite the size of a Volkswagen. Lake Sinclair drive is full of good size hills compared to just a few miles away.
I learned about it years ago when I visited a buddy's hunt club near Columbus. The first thing I noticed when I stepped out of the truck was the sandy soil filled with pieces of sea shells.
We have a lease in Johnson county on the Oconee river. You can find red clay at the higher elevations and sand,like beach sand, in others. We got a ridge along the river that in some places drops 100’ in elevation pretty quick. Pretty cool place