As MacKenzie mentioned below, we spent the weekend at Arches National Park, down in southeastern Utah. Along with sandstone fins, Balanced Rock, and the eponymous arches, we saw this feature, which is not listed in any park literature or guidebooks:
That is just uncanny. A quick Google search indicates that we are not the first people to notice this particular geologic feature, which can be found just west of the main park road, north of the Petrified Sand Dunes. It also seems that the National Park Service is aware of this. There is a paved turnout on the park road right in front of this rock. There are no signs there, nor are there any other notable features listed on the park map in this area. I'm guessing that the NPS built this turnout after noticing numerous cars pulling over here to take pictures. While they don't want to publicize this formation, they must have felt that, for the sake of safety and the roadside vegetation, that they'd better give people a place to pull over and take pictures like the one above.
Who says geology is boring?