Ice Dam flood? We Can Top That!


Himalayan glacier disaster highlights climate change risks, shouts the headline; and it’s only one of many similar which the Associated Press has pumped down the wire since last week’s collapse of a glacial ice-dam in India’s far north.

I don’t want to make light of the event, which killed hundreds of people, but I think a sense of proportion is indicated here. If you want a real example of the damage global warming can do, you need only cross the Cascades to visit a land where the same phenomenon scoured the earth, not once but repeatedly, utterly destroying all macroscopic life.

It has been almost a century since Carleton Bretz and J.T. Pardee suggested that the huge stretch of barren buttes and terraces that form most of central Washington state were formed by inconceivably huge floods. Fellow geologists jeered. Then Pardee identified a possible source of the inundation: a great lake (great as Lake Huron is today) held back by a lobe of the retreating polar glacier which covered North America at the time, at the site of Missoula, Montana today.

Bretz and Pardee ignored the jeers and went on patiently collecting evidence. A new generation of geologists paid attention and gathered more evidence, from points as widely separated as Walulla Gap on the Columbia to the Willamette Valley. In time they realized that there had been not one huge flood but many, stretching over as many as 5000 years and ending only about the time of the first signs of human occupation around 10,000 years ago.

So extensively have these inundations been documented that it’s possible to create an animated graphic of the furthest extent of the inundations, and though they’re not up to Industrial Light and Magic standard, they make their point. Supplemented by a dozen short documentary explorations by Central Washington University prof Nick Zentner, the housebound amateur geologist can now explore almost every nook and cranny, coulee and bar of the biggest damn floods the world has ever seen, all courtesy of You-Tube.

Roger Downey
Roger Downey
Born in Canada moved to Peru's altiplano at the age of six; came to the U.S. at 10 to discover that you don't use your feet to dribble the ball. Learned from the git-go that "America" is an idea, not a place.


Please enter your comment!
Please enter your name here

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Comments Policy

Please be respectful. No personal attacks. Your comment should add something to the topic discussion or it will not be published. All comments are reviewed before being published. Comments are the opinions of their contributors and not those of Post alley or its editors.