"This is simple to answer. They are all pointing toward the coastline...i.e., downhill. " Okay, good answer, I understand.
I was in the Charleston area in the early 60's and while walking along a marshy area of the bay, I found a two inch long, black shark tooth. I was told that they are common and are about 50 million years old.
If you were near Charleston, those shark's teeth would be less than 2 million years old. You'd have to go up near Columbia to find anything in the 50-million year range.