Welcome to the Age of Mammals“No region in the world shows a more complete sequence of Tertiary land populations, both plant and animal than the John Day Basin.” - Dr. Ralph W. Chaney
Preserved within the assemblages of the John Day Basin is a fossil record that spans over 40 million years. If each time period recorded here is a page in a book, the National Monument holds an entire chapter of Earth’s history which tells the story of changing life and landscapes. Explore each of the fossil bearing assemblages of the John Day Basin and imagine how much life and the landscape has changed in the past 50 million years. What will it look like in another 50 million years?
Clarno Nut Beds (44 Ma)
Oregon was a hot, wet, semitropical place filled with a wide diversity of plants including palm trees and avocados.
Hancock Mammal Quarry (40 Ma)
Herbivores such as brontotheres, tapirs, oreodonts, and horses were found in the Hancock Mammal Quarry .
Turtle Cove Assemblage (29 Ma)
Turtle Cove is the thickest and most productive fossil-bearing layer within the John Day Fossil Beds, yet few leaf fossils were preserved.
Last updated: December 29, 2017