This photo during my descent from the San Gabriels yesterday may not look like much, but I tried to capture the contrast between rock types. As I walked along the trail a few miles before Soledad Canyon Road, the surface went from white to black in the span of no more than 4-5 inches. I looked up the side of the trail and saw a clear line with white rock smashed up against black rock. I had seen similar differences before, but not this stark.