I attended the EcoAddendum walk at Boat Rock Preserve, led by Kathryn Kolb.
When Pangaea formed, volcanic islands that had been located off the coast of Georgia got squished into Georgia. As a result, plutons were formed (as well as the Appalachian Mountains) below ground. Surrounding rock eroded, leaving the intrusions of granite exposed, including rock outcrops like Stone Mountain, Panola Mountain, and Arabia Mountain, as well as the rocks at Boat Rock Preserve.
Another fun fact is that granite erodes to clay. The clay that Georgia is well-known for comes from the Appalachians, which used to be as high as the Himalayas, but have eroded.
Kathryn laid out her "Tape of Time", showing in relative terms when various geological and ecological events occurred. It was interesting to gain perspective on how recently humans and recorded history are in the scale of geological time.
The Tape of Time
Kathryn told us about the forest here. We can tell that it is a native forest in the sense that the soil is original. The land was never used for farming, because of the difficulty of farming with all the rocks. That said, the timber has been cut, so the trees are mostly young.
But since the soil is original, some native species remain that didn't survive farmed areas: wild ginger, black oak, and short-leaf pine. There are also lots of sourwoods and blackgum in the woods here.