In my online search for area information, I found this curious article about a conversation between Bob Jones and Jim McCulloch at http://stone-bridge.blogspot.com/2005/05/traces-of-other-americas.html
“Once at Cornudas Mountain, which is near Alamo Mountain and product of the same episode of volcanism, I noticed a curious slickness high up on some of the giant boulders tumbled arou
nd the base; it looked like something had been rubbing against the rock. But these spots were ten feet off the ground and on vertical slabs.
I had seen this kind of slickness on the floors of Indian rock shelters, where the Indians had used the shelters for centuries, sometimes millennia, and thus the rock had been worn shiny, polished and oiled by human feet.
We mentioned this to an old rancher who lived near Cornudas all his life, a man named Bob Jones who was one of a type the west is still full of, men whose reading and thinking and isolation lead them to toss out startling but offhand conversational insights. He poured his coffee into his saucer to cool it, an old custom that is dying out; and he said “Oh, I figure it was mammoths that made those slick places high up on the rock.”
“Of course” I thought, suddenly illuminated, “a mammoth rub.” It was really pretty obvious. Neither trees rubbing against rock, nor glacial forces, could make such a polish. But even though it seemed intuitively right–certainly no other animal could have rubbed against these rocks–I considered it a matter of conjecture, a brilliant rancher insight into something science would not care enough about to investigate. Later, though, I found an old report in a 1947 issue of Science, where some geologist took a thin section from the surface of this same slickened rock and by heating it extracted oil, ten or fifteen thousand year old rancid body oils, apparently of animal origin.
I later found other mammoth rubs, and every time I could get up to reach one, I would rub my hand over it. Touching the smooth old rock was the next best thing to touching the mammoth itself, old cool smooth rock that soothed great itches thousands of years ago.”