This picture is a little hard to understand,
but it's worth the effort. We're at the top and back of the cave; the black is the ceiling, that has been covered with the grease and soot from cooking. The floor is smooth here, whereas at the front (opening) of the cave it was layered with rock. I didn't touch the ceiling (because of threat of losing a hand), but it looked like you would be able to pick off the charred rock.)