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Columbia River Near Vantage – Sunland Road – Grant County, WA

Eastern Washington State, and in particular that portion known as the Columbia Basin, is one of those places where Mother Nature treated the land with brutality.

Beginning about 16 million years ago the land was subjected to repeated lava flows over the next 10 million years that left the land covered in a cap of basalt 1 to 3 miles thick. That is a serious case of getting stoned.

Much later, some 15,000 to 30,000 years ago, came the great floods the scoured the land not only down to the basalt deposits but actually through them leaving the land all cut up, with the most massive cut being that for the Columbia River. These floods started in Western Montana and went gushing, rushing, and flushing the land right into the Pacific Ocean.

On a more human level, one of the interesting story is how one geologist, J. Harlen Bretz, in the 1920’s pieced together the story of these Spokane Floods (now more commonly known as the Missoula Floods) and how they cut through the basalt to form what he named the Channeled Scablands. What I find sad is his peers pretty much rejected his research. Forty years later Harlen was vindicated. What is awesome is he lived long enough to see this happen. That is justice in my world.

The short story of one of these estimated 40 or more flooding events is that at the end of the last ice age a massive ice dam would form that held back a lake that covered significant a chunk of Western Montana. This breakup of the dam would eventually collapse cataclysmically. When all this hell broke loose, the water would rush across the land at 80 miles per hour and unleash a force estimated at about 4500 megatons of TNT.

So what does mean? Glad you were wondering.

To help put this last number in perspective all the nuclear bomb testing that occurred through the end of the 20th century amounts to a about 510 megatons. For those of you keeping score: each flood unleashed about 8.8 times the amount of energy of all the atomic bomb blasts in the 20th century.

The view in this image shows you what all the energy did to the land.


Copyright 2012 By Katherine Johnson – All Rights Reserved.