From the Missions to the Sea: Driving the Path of the Missoula Flood with Cataclysms on the Columbia as a Guide

Fri, 19 Dec 2014 17:00:54 +0000

There are many places in the world where one can see the dramatic effects of cataclysmic events carved into the face of the earth, if one knows how to look. Eastern Washington is one such place, and the revised second edition of Cataclysms On the Columbia: The Great Missoula Floods will show you where and how to look.

I grew up in the Pacific Northwest, surrounded by the effects of the Great Missoula Floods. But I never knew about the floods until I caught episode 1001 of the Oregon Public Broadcasting program Oregon Field Guide. The program covered the Missoula Floods in a general way with some interesting animated and visual effects, but did not really delve deeply into the geology surrounding the events, or into the detective work of the scientists who pieced together the puzzle of what happened from their observations of the geological record. Over the years since watching the program, I have happened upon sites impacted by the floods, with their attendant interpretive signs giving me just a little more of the context of the story. While visiting the national bison refuge outside St. Ignatius, Montana, I discovered that I was standing near the bottom of Glacial Lake Missoula. While on a detour coming back to Portland from Spokane, I stumbled upon Dry Falls and got to see firsthand the deep scars that the floodwaters cut into the Palouse region of Eastern Washington. And taking my young children to the Oregon Museum of Science and Industry, I discovered an interactive exhibit devoted to the floods that put the depth of the flood waters in perspective. But it wasn’t until I began working at Ooligan Press and found Cataclysms on the Columbia in our back catalog that I felt like I’d been given the key to unlocking a deeper understanding of the floods and the detective work it took to initially put them into a geological context.

The Great Missoula Floods were a series of geological events that took place near the end of the last ice age, between 15,000 and 18,000 years ago. At the time, there was a massive inland lake in Western Montana. At its maximum size, it was roughly 2,100 feet deep, holding more than 530 cubic miles of water. These 530 cubic miles of water were held in place by a dam of roughly 50 cubic miles of ice. This ice dam gave way and reformed somewhere between 40 and 90 times during the life of Glacial Lake Missoula. Each time the dam broke, the waters behind it were released in a massive three-day flood that scoured its way through Eastern Washington, swelling the Columbia River to over 60 times the flow of the Amazon, and erupting from the mouth of the Columbia Gorge just west of Portland. As the floodwaters spread out into the lower Columbia and Willamette Valleys, they dropped more than fifty cubic miles of accumulated topsoil and boulders the size of small houses. At the height of the flood(s), waters in the Portland area would reach a depth of 400 feet—only the top floors of Portland’s tallest buildings would have been visible.

Cataclysms on the Columbia tells the story of the Missoula Floods and their geological impacts in great detail and is the first publication to attempt to relate the geological story in a way accessible to everyday readers. Also included in the text are a general introduction to geology, sections devoted to other ancient cataclysmic floods, and the story of J Harlen Bretz, an early champion of the Missoula Floods theory, and his struggle to gain support for what would eventually be understood as fact.

The final section of Cataclysms on the Columbia follows the path of the floodwaters from outside Missoula, across northern Idaho to Spokane, Washington, southwest to the Rathdrum Prairie where the waters backed up and formed Glacial Lake Columbia, to the channeled scablands of the Grand Coulee and Dry Falls, to the eastern end of the Columbia Gorge, downriver to the Portland-Vancouver basin the Willamette Valley, and to the Pacific. Someday, maybe, I’ll make the journey myself, as the authors of the blog Ice Age Floods have done. I’ll have Cataclysms on the Columbia to guide my journey and my understanding.

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