Guess it’s a context thing in relation to past artifact production on these specific spots. Not any local reliable supplies of a specific chert or flint so when I get into a 20 foot circle that contains Knife River Flint from over 200 miles away and other flakes of various material pretty sure they didn’t occur naturally that way on top of the ridge. These prairie sites saw a lot of animal processing so do occasionally find perfectly shaped beautifully crafted scrapers and some days you find these