Wider pit on top, usually used for cracking nuts.
Smaller, usually used for point sharpening and known to be used for bow drill fires.
The attached was found at site with mostly archaic artifacts/hearth. If you find something similar in an area where there’s no other artifacts, then you got a question whether or not it’s natural for sure. The one in the picture also has the same markings on both sides. It was found with Flint flakes, got a couple of other absolutely incredible and unusual finds. Hopefully someday I’ll be able to post those as well.
It is often thought that pitted, Notting stands, more frequently in archaic settings.