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Riled Up is a journal of science, the environment, exploration, new technology, and related commentary.  Contributors include scientists, explorers, engineers, and others who provide perspectives and context not typically offered in general news circulation.  For interested readers, additional resources are included.

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Bobbing Boulders
Hugh Bollinger

Bobbing Boulders

Illhorn and Illgraben valley, Switzerland (credit: Wikipedia)

Geomorphology is the study of landforms and the processes that have created them. Whether mountain building, erosion, drifting continental plates, wind, or random events like earthquakes, floods, and landslides these processes have produced all the Earth's features. One stark result of a geomorphological process was landscape-scale building are the Grand Coulee region in Washington State. In this case, the features were formed in the geologic 'blink of an eye'.

According to research investigations, ~18,000 years ago a lobe of the Pleistocene icecap reached into what is now Idaho and blocked present-day Lake Pend O'reille. The ice dam, perhaps 2000 feet tall, cut off drainage of the Clark's Fork River creating a gigantic lake reaching far into western Montana. As the lake deepened, the ice dam began to float and leaks likely developed in several places. In a massive event, the dam completely failed. The volume of water stored behind it was release, and estimated at 500 cubic miles of water (1 cubic mile=1,101,117,147,352 gallons) in ancient Lake Missoula. The resulting mega-flood may have happened over just two days. A flood of that scale, equivalent to 10X the combined flow of all the world's rivers, would have been powerful beyond imagination. Trillions of gallons of water were released across the land cutting the sharp canyons visible today.

Two brief videos from Switzerland capture a similar, though much smaller, event when a huge volume of water was released by torrential rains across unstable mountain slopes. The boulders bobbing in the debris flow are the size of mini-vans and illustrate the power of such events. As the saying goes, geomorphology rules! WHB

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