Theres found terrain and then there’s found natural terrain. Outside of the Moab footage, this spot in Sierra Nevada filmed by Brandon Rein is the most skate able natural rock formation I’ve ever seen. It looks natural for the most part, but there are definitely sections that look like a concrete surface, which seems highly illogical. Brendon does not give any info however, so you’ll just have enjoy the clip. The skateboarding only makes up about a quarter of the footage in the entire video, so you’ll have to wait for it.
SFGate has posted some pictures in a feature called Four decades of skateboarding in San Francisco. It’s part of their Let’s Go to the Morgue! series where they dig up old photographs from the San Francisco Chronicle. Better versions of the picture, along with a little commentary are on the SFGate blog. The earliest photo dates back to 1964, and the last one is from 1994.