Sheep Rock is one of the three units of John Day Fossil Beds National Monument, Oregon. The place is so named because of the resemblance between a sheep and one of the mountains in the unit. While the Painted Hills Unit is dominated by red layers, the Sheep Rock unit is characterized by green claystones, which are composed of volcanic ash containing a mineral called celadonite. The appearance is a product of chemical weathering that happened millions of years ago. The picture at the bottom was taken at Smith Rock State Park.