We have locations here where the natives found the particular type of stone they preferred for knapping arrowheads and spear points. Tribes would camp there while the artisans knapped the tribes needs. No sense it carrying the whole stone when you only need a little of it, and hunter/gatherer tribes could easily camp about anywhere, for awhile. Over thousands of years these locations accumulated not only considerable knapping debris, but a lot of artifacts discarded or lost by succeeding cultures using the site, which made archeologists say, heap good spot find stuff.