Welcome to the Cenozoic, 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.
Please use the following links to explore each of the fossil bearing assemblages of the John Day Basin and imagine how much life has changed in the past 50 million years.