Reidel discusses Ice Age Floods and the formation of the Columbia River system
To geologist Steve Reidel, a rock is not just a rock. Rocks like basalt, which covers the entire Pacific Northwest stretching from Spokane and Boise to Portland and the Willamette Valley, tell a rich geologic story covering millions of years.
Steve Reidel
In October, Reidel, a researcher at Pacific Northwest National Laboratory, provided a public lecture on the role of flood basalt and the Ice Age floods in the geologic evolution of the Columbia River system. His presentation, in the Columbia Basin College Theatre in Pasco, attracted a large audience.
The talk was part of the Community Science and Technology Seminar Series co-sponsored by PNNL and CBC. The series, launched in 2001, features a broad range of speakers who discuss the new, the innovative and the awe-inspiring changes taking place in our world. This series is free and open to the public.
Reidel told the audience that the geologic "floor" of the Pacific Northwest region consists of basalt laid down more than 6 million years ago. Immense lava floods swept over more than 100,000 square miles of Washington, Idaho and Oregon. The basalt is estimated in excess of two miles deep in many areas.
Then, about 2 million years ago, ice age glaciers from British Columbia continued to fashion the geology of the Northwest. Glacial ice and debris formed great dams in the mouths of valleys and enormous lakes materialized behind them. The largest glacial lake ever known was formed in present-day Idaho and Montana. Lake Missoula was formed behind a towering 2000-foot-high ice dam. The waters of Lake Missoula burst the dam on several occasions, causing the greatest floods known to occur anywhere in the world. The channeled scablands northeast of the Hanford Reservation were formed by the erosion and depositing effects of massive flooding.
"Although the Columbia and Snake rivers appear to have been here since time began, they have had a long and complex history to reach their present locations," Reidel said. "Eruptions of the largest lava flows known on earth combined with tectonic forces channeled the rivers into the central Columbia Basin. The ice age floods completed the final stage of their evolution, giving us the Hanford Reach."
Reidel is one of the most knowledgeable experts on the geology of the region, having spent more than 30 years in geologic research for WSU and DOE contractors, including Rockwell International, Westinghouse Hanford and PNNL. He has conducted a variety of research for DOE, other government agencies, and private industry. These projects include research on the Vadose Zone Groundwater Integration Program for DOE and the Gas Storage Project for the Pacific Gas Transmission Company. Reidel, along with more than 100 scientists with a background in geology at PNNL, are using conventional and innovative tools, such as computer modeling, to explore and characterize the geology of the region.
Reidel also is an associate professor in the Department of Geology at Washington State University in Pullman, a member of the Washington State Advisory Committee on geologic mapping, a member of the Geological Society of America, and a member of the International Association of Volcanology and Chemistry of the Earth's Interior. He also writes a column for the Tri-City Herald on local geology.
