Old Rock Art

I just ran across this article yesterday, and was reminded of a discussion Arthur Wilderson and I had recently where I talked about the difficulties in dating rock art.  Larry Benson, a researcher at the University of Colorado - Boulder, has used multiple lines of evidence to date these petroglyphs found near the shore of Pleistocene Lake Winnemucca in Nevada, to between 10,500 - 14,800 BP.

Benson and his colleagues used radiocarbon assays on carbonate concretions on the surface of the rock as well as geologically dated lake levels to bracket the time period when the rocks would have been above the water and available to be incised and then submerged below the lake level and covered with carbonate. He believes this may be the oldest securely dated rock art in North America.

One of the things I found interesting about this discovery is that the art is abstract. Most of the rock art that is attributed to Pleistocene age in North America has been based on depictions of extinct megafauna.