As you drive to Billings on US310, just north of Greybull you pass by the Sheep Mountain Anticline. An anticline is a fold in which the rocks get younger as you move away from the axis (center) of the fold (as opposed to a syncline, in which the rocks get older as you move away from the axis).
At the south end of Sheep Mountain (above) is a bright red rock layer; as at Wind River Canyon and Shell Creek Canyon, this is the Triassic Chugwater Formation. The grey rocks just to the left are the Permain Phosphoria Formation.
Below, the buff-colored rocks at the top of the mountain are once again the Mississippian-age Madison Limestone.