Thursday, May 24, 2018


Prominent on my bucket list is the Channeled Scablands of Eastern Washington state.  Before you have me committed, let me explain.  This was the scene of perhaps the greatest flood in world history, the Biblical Flood, if you will.  Planetary scientists are interested in this area because the dry channels resemble those on Mars.  

Near the end of the last Ice Age, a wall of water up to 1000 feet high came pouring down the Columbia River basin at a speed of 65 mph.  The flood carved out the Grand Coulee valley and thoroughly cleaned up Washington (which wasn't called that at the time).  It created enormous potholes and ripples as much as 50 feet high which becomes evident when you view the landscape. 

There have been several theories of how this happened.  The most generally accepted one today was proposed by the geologist J. Harlan Bretz about 100 years ago.  For many years, scientists in the geology establishment thought the guy was nuts.   For the establishment, the accepted orthodoxy was uniformitarian--that all changes in geology occurred slowly, over many eons.  Bretz turned this theory on its head. 

Bretz worked diligently compiling evidence, and eventually he won over most of the non believers.  By 1979, Bretz was mainstream, if you will.  For his achievements, he was awarded the prestigious Penrose Medal, the highest award of the Geological Society of America.  

The scenery in this area west of Spokane is certainly unusual.  Once can see enormous boulders weighing many tons strewn around the area like they were thrown out there.  They do not match the rock types that surround them.  These rocks are called glacial erratics, foreign to the area.  Erratics can be transported hundreds of miles by glaciers, or in this case by ice-rafting from the flood.

In most areas the topsoil was stripped from the land.  The underlying rock is volcanic basalt which is easily chipped away by the action of water.  The U-shaped valley is framed by thousand foot cliffs on either side.  In some areas there is a small stream in the middle. In other areas, the valley is completely dry.  The stream could not have created that valley.

Bretz's theory is that during the last Ice Age, an ice dam blocked off the ancient Lake Missoula in present day Montana.  The lake contained as much water as Lake Michigan.  The climate got warmer; the ice melted; the ice dam broke, and, of course, all hell broke loose.   According to Bretz, "the channels run uphill and downhill, they unite and they divide, they head on the back-slopes and cut through the summit; they could not be more erratically and impossibly designed."

The less accepted theory was propounded by author Graham Hancock who believes that the ice sheet was hit by a large meteorite (asteroid) which caused a sudden melting of a large area of ice.  Now it's possible that both theories can be true because new evidence shows there have been many such floods in the area.  That would indicate that the ice dam broke on several occasions. 

We saw evidence of this on our visit to Dry Falls, south of the Grand Coulee Dam, where the cliffs were terraced.  That indicated that slabs of basalt were stripped off at different times by different floods.   For several weeks, approximately 12,000 years ago, Dry Falls was as spectacular as Niagara Falls. 

This area is off the beaten path, and you won't see busloads of tourists blocking your view.  The starkly beautiful scenery is worth the trip. 


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