I was surprised, though, by the geological scenery as well. I had studied the geological maps and realized we would be spending most of the day in the Eocene-aged Green River Formation. I was expecting to see some badlands topography similar to what we saw the previous day at Fossil Butte, but the canyon was deep, very rugged, and wonderfully scenic. It turns out that the lake that formed the Green River Formation had shorelines, and included riverbeds and alluvial fans that carried sands and gravel. These sediments formed a series of cliffs that were ideal sites for rock art and for building granaries.
They actually can be picked up off the ground almost anywhere in the valley.
OK, I promised prairie dogs...when we stopped to ask for directions at the beginning of the day, we realized we were stopped in the middle of a prairie dog town.
The pictures of the prairie dogs and petroleum/gas stuff are courtesy of Mrs. Geotripper.