Mr. Rogers was a physicist and engineer with the China Lake Naval Weapons Laboratory until retiring in 2002. He has written numerous papers on hunter-gatherer cultures of the Great Basin and the archaeology of rock art. He holds masters degrees in physics and anthropology.
He gave us an excellent presentation of the petroglyphs of the Coso region which includes the upper Mojave Desert and southwestern. He explained how obsidian can be dated and its origin traced. Obsidian arrowheads and tools are found along early native trade routes and their origin can be identified.