Stone Tool Analysis: Potlid
A potlid is a disc-shaped flake that is flat on one side and convex on the other. Potlids initiate at a flaw on the stone, often microscopic in size, located at the apex of the convex side. The stresses created by extreme temperatures, or temperature change, cause the stone to fail at the flaw and a crack to form. The fracture front propagates outward and upwards towards the free face of the stone, popping out the potlid flake from the surface.