In 1865, pioneer minister and amateur scientist Thomas Condon rode through this dry land on the first of many visits and discovered the imprints of countless fossilized leaves near the Painted Hills, leaves from plants that could not survive the modern near-desert environment. These fossils opened a window onto vast changes in climate, plants, and animals. The colorful Painted Hills are part of the lower John Day formations, with layers of the Clarno formations and Picture Gorge Basalts visible nearby. At Sheep Rock and Clarno units, other aspects of the John Day Fossil Beds can be explored.