I would think that most of the artifacts would've been made and used after the glaciers receded, but I could be wrong. Most of the artifacts in my part of Georgia, to my knowledge, are from a couple thousand to a couple hundred years ago when the Creeks were pushed back. Google Earth is a useful tool for spotting likely areas to search. I few years ago I decided to plot where I was finding alot of flakes, broken points, and a few good ones on a satellite map of our property. It ended up being an almost straight line all the way across, which would indicate a small migration route. Who knows how long it was in use, but it was very interesting.