White Shaman, Val Verde County, TX.
Photograph Peter Faris, March 2004.
Also, I recommend Boyd's book Rock Art of the Lower Pecos, Carolyn E. Boyd, Texas A & M University Press, College Station, 2003. While I do not agree with some of her conclusions, I did find it full of information (and some good pictures) about the amazing rock art of the Lower Pecos, and even some of her supporting evidence is interesting and worth knowing.
NOTE: These things come up regularly. I would like to refer readers to previous RockArtBlog postings on Ogam in North America (April 20, 2009), and A Misplaced Reliance on Statistical Analysis (January 25, 2011) which addressed a report that statistical analysis proves that symbols painted on cave walls in Europe constitute a written language.