The main hiking area in the Sheep Rock Unit of John Day Fossil Beds National Monument is Blue Basin, centered on an outcrop of grey-blue badlands, heavily eroded, lacking any vegetation and split by a branched ravine, which provides a course for the 0.8 mile Island in Time Trail, the best way to see the rocks close up. Far fewer people hike the 3 mile (loop) Blue Basin Trail, which circles all around the basin, climbing quite high above so giving good views not only of the badlands but also up and down the John Day River valley. The basin is one of the more important fossil sites in the monument, and while no specimens are visible in a natural state, there are three replica fossils embedded in stone along the Island in Time Trail. The brightly colored rocks were originally volcanic ash, resulting from eruptions around 29 million years ago.
