I trust this one is a joke...
I know the BLM and FS don't advertise a lot of their rock art sites, to prevent vandalism. Same thing with some of the rare animals such as Midget Faded Rattlesnake dens. People either vandalize or remove them (yes, remove rock art by cutting slates out of the rocks) to sell or collect. The rare reptile market is bigger than many think, and the indian artifact black market is HUGE..