The John Day Fossil Beds in Eastern Oregon contain some of the most accessible and extensive fossil beds in North America. It also has an unusually varied geological history and the rivers have opened that book so we can read it. The John Day Fossil Beds National Monument includes 3 units: Sheep Rock, Painted Hills, and Clarno. These three offer an abundance of fossils and between the three, also cover most of the region's geological history. Starting with the most recent, Picture Gorge exposes lava flows which ended about 15 million years ago. Just west of the gorge is Sheep Rock. The highest layer of lava on Sheep Rock is the same age as the lowest layer in Picture Gorge. As you go down to the river you are going back in time. Just across the river from Sheep Rock are the Thomas Condon Paleontology Center and the Cant Ranch. Beneath the lava flows are thick deposits of volcanic ash containing fossils from a warmer and wetter climate than today's. Older volcanoes to the east and newer ones to the west blanketed this region with ash.Each layer of volcanic ash is a page in the story of changing climate, geology and biology. Around 26 million years ago this was hardwood forest. The lowest strata of the sheep rock unit are about 28 million years old. There is a publicly accessible fossil bed behind Wheeler High School in the town of Fossil. Here for a small fee you can find fossils from a meta sequoia forest from 32 million years ago. In the Painted Hills Unit the multicolored layers show that the climate cycled from warm/wet cool/dry 35 million years ago. Oxides of iron, manganese and magnesium in clays, zeolites and opal make spectacular scenery. The layers here are older than the Sheep Rock strata and the land and its inhabitants were even less like the present. At 40-44 million years old, the Clarno Palisades are the oldest fossil beds. The climate was much wetter, producing lahars-mudslides of volcanic ash, entombing denizens of a near tropical forest. Before the formation of the fossil beds, about 70 million years ago, this was the Oregon coast. Goose rock, near the Cant ranch, is a bit of tropical beach from 100 million years ago. Two hundred million years ago in the age of dinosaurs this was a tropical sea.
NATIVE WISDOM about the John Day Fossil Beds
John Day Fossil landscape intermission picture
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