In early 2013, I was out hiking in the backcountry of Joshua Tree National Park and came across this solitary boulder with petroglyphs and pictographs. They are inside of a concave, hollowed out section of a large White Tank monzogranite boulder along what could have been an ancient trail. The area was last used by the Serrano and Chemehuevi.
This is an interesting site. If you visit across it, please respect it and take only pictures. Some of the petroglyphs and pictographs seem to have been chalked. Please do not chalk (or touch) any pictographs. Touching them helps to wear away the pigment.