Columbia River Basalt Group – Related to Cascade Volcanoes?
Hello young people. The Columbia River Basalt, near Quincy, Washington. We're at Quincy, Washington but we could pick
any spot between Spokane, Washington and Seaside, Oregon to do this show. These brown layers of basalt are everywhere
in the places where the Ice Age Floods did massive amounts of erosion thousands of years
ago. There's more than 300 layers of basalt here. 300 separate volcanic eruptions and the stack
of basalt is more than two miles thick in places. The lavas started erupting 17 million years
ago. And flooded a landscape, buried a landscape
in lava. The obvious question is which volcano erupted. Was it Mount Rainier, Mount St. Helens
The answer is none of them. The Cascade volcanoes do not match the chemistry
of these basalt lavas. These are lavas came from the east. They erupted out of fissures. Deep cracks that emitted Hawaiian like lava. Starting 17 million years ago. Fissures that formed related to the birth
of a hotspot that's now underneath Yellowstone National Park in Wyoming. The present is the key to the past. To really visualize eastern Washington 17
million years ago we need to go to Hawaii today. Those Hawaiian lavas today are the same kind
of lava flows that we have here.
Lava flows in Hawaii, very fluid, the most
fluid lavas we have in nature. Average less than three feet thick. Here in eastern Washington the lava flows
average 100 feet thick. In Hawaii, the lavas travel on average three
miles in length. Here in eastern Washington, many of the lava
flows traveled 300 miles. And in Hawaii, 30 miles are covered by a typical
flow. Here in eastern Washington, 30,000 square
miles of area buried. The Columbia River Basalts near Quincy, Washington..