Just around the corner from Hidden Valley in Joshua Tree are two pictograph sites. They are not well known and only a few pictographs are here but they are still well worth a visit. Both sites were once used for bouldering (rock climbing) but are now off-limits. The climbers definitely used their imaginations when naming the sites.
The pictographs at Zombie Woof are difficult to see, so you will have to look carefully. The Shipwreck is much easier. I used DStretch on both of them to bring out the details.