NOT REALLY ROCK ART – ARBORGLYPHS (TREE RUBBING MARKS):

Grooves worn in the cliff by a tree,

Signature Rock, Boise City, OK,

May 12, 2006. Photo: Peter Faris.

On some occasions you will find wide, smooth abraded areas on a vertical rock surface that looks vaguely reminiscent of the ground-out basin of a bedrock metate, or a wide tool mark. These markings, however, were not always created by people. One natural phenomenon that sometimes produces these markings is rubbing by a tree trunk or limb that has grown in contact with the rock face and is moved by the wind. The most appropriate term for these would be dendroglyphs, from the Greek dendro (tree) but this term has already been applied to symbols carved into the bark of a tree. As a substitute I suggest using the Latin word arbor (tree) so these could be termed arborglyphs. Of course, if you are one of the people who calls the symbols carved into tree bark arborglyphs, then maybe they should be called dendroglyphs. In either case they are markings on the rock that were created by trees.

Grooves worn in the cliff by a tree,

Signature Rock, Boise City, OK,

May 12, 2006. Photo: Peter Faris.

I have seen examples of this phenomenon in a number of places. Although easily spotted while the tree that created them is still alive and in place, they can be much harder to recognize when the tree is gone. I have seen them on a number of surfaces with no sign of a tree within present reach. In one instance the mark was considerably higher on the cliff than the tops of the contemporary trees. A tree had produced the mark on the cliff so long ago that the valley bottom had eroded down a number of feet since that mark had been created. The species of trees that grew in that environment were not tall enough to reach that mark from the present valley bottom. So if you are viewing what looks like a metate or a large, wide tool mark on a cliff or other vertical rock surface, keep this in mind, it just might be a natural phenomenon.