The rock layers of the John Day Fossil Beds spread far beyond the boundaries of the National Monument.
The oldest layers are on the bottom, the youngest layers are on the top.
To learn more about each of these different Formations click on the links in the index on the left side of this page. They are (from youngest to oldest) the Rattlesnake, Mascall, John Day strata, and Clarno formations.
Did You Know?
Fossils from the Clarno Unit show that 44 million years ago, in what is now a near desert in Oregon, crocodiles and palm trees flourished.