EXPERIENCING THE ICE AGE FLOODS, PART IV

After circling Grand Coolee Dam and retracing our route partway back down the upper portion of Grand Coulee itself, we cut across country to the west to intercept Moses Coulee where Highway 2 crosses it in Douglas County. Then by flying southwest, the way much of the flood waters traveled, we viewed many features of cataclysmic alteration of the surface features. These included dramatic vertical walls, more hanging valleys, and considerable amounts of materials which were carried from the scablands, sifted and graded enroute, and deposited here in bottomlands that allowed slowing of the passing floods.
Once the floods exited the coulee and joined the basic route of the Columbia River, additional silts and sands and fine sediments fell out of suspension and left gigantic sand bars in the river floor. West Bar (above) is one of several extensive deposits in the lower river channel. Most running water leaves standing ripples on the sandy bottoms and the scale of these common, typical ridges and valleys are a measure of the strength and amount of the flow that formed them. In the case of the bar pictured (only a few miles downstream from Wenatchee, WA) the giant ripples lay patiently in place for years before they were recognized for what they are - evidence of an incredibly humongous flow of water which was needed to form them. In fact they are so massive in scale, and although many people searching for evidence to prove or disprove various theories about the Ice Age Floods actually walked over them on multiple occasions, it was not until the age of flight allowed the ripples to be seen from the air that they were recognized at all.
A few more miles down river from the giant ripples, are several spectacular features. These are huge retrograde, dry waterfall coulees which were formed when flood waters that had cut the channeled scablands and filled the Quincy Basin region to the northeast overflowed into the Columbia just north of where Interstate 90 now crosses the river. As the water dropped over the steep walls in volumes unbelievably wide and deep, the columnar basalt and other volcanic deposits steadily gave way causing the abrubt edge of the cateract to march upstream as the walls beneath the floods collapsed. In this way Potholes Coulee and Frenchman Coulee were created. In the former (pictured above) large bowls were also caused by the weight, violence, and drop of its abrasive load, thus the "Potholes" name. In the latter (pictured below), the name was taken from the Frenchman Hills which directed the torrent to this location where a deep and rather long channel was carved back from the river it sought to reach.

Next time David and I fly over some of these fascinating geological anomalies, we will be able to take better pictures (with the windows open to eliminate the foggy results of shooting through crazed plastic) and possibly better angles to take advantage of lighting and of contrast caused by shadow. This may become a years-long effort because the total terrain spans several states and the effects left behind are so varied. Some of them are also becoming obscured by the intervening centuries. There is no way possible to see it all in a single flight, unless perhaps from the space shuttle, in which case close-ups are hard to do. I'm up to the project as long as David's interest holds. That's a lot of territory to cover, and much of it deserves a "boots-on view". Really, I think that at some point in coming summers, some of you folk who are also intrigued by this grand mystery should join us on a camping tour of the entire floodlands from Montana to the Pacific Ocean. Is anyone interested in that idea?

Meanwhile, thanks again, Son, for a fascinating and thrilling Father's Day gift. I always enjoy flying with you, but to feature the "Floods" and to include an expert guide and narrator was just genius! (Y'all readers see previous blogs to learn about about Bruce Bjornstad.) I know you are skilled at matching a perfect gift to each recipient, but this was simply overwhelming! I am enjoying bragging about it (and you) far and wide. Well Done Indeed!