I just returned from a trip along part of the Columbia River near Grand Coulee Dam and Wenatchee. The photo is Steamboat Rock in Banks Lake. Here is the greater explanation:
The CR comes southward from the international border through Roosevelt Lake, a large and wide section of the Columbia, really, formed by the backup from Grand Coulee Dam. This large facility is complex, and management stores water according to how much and when power is created at the dam itself. Some is in Roosevelt Lake. More is the water pumped uphill to what was called Banks Lake after it became part of the total facility. It can be used with care for boating and recreation, and naturally its borders change with power needs and climate. The large body of water narrows down at Coulee City, where major east-west highway 2 crosses the Columbia. A person visiting the area by car should be sure to travel the road from the dam to Coulee City, not only for the lake's views, but the spectacular and ragged rocky cliffs or walls that soar almost a thousand feet on either side. It is a vista that is reminiscent of Utah's canyons, only this one has water. This week with spring sun at work the cliffs sported green shrubs and even green growths on some of the rocky faces. Mid-May was a perfect time to review my earlier research observations.
There is more to this story, a thrilling geological saga I will try to abbreviate. During the most recent Ice Age what is now central Washington State and on into adjacent British Columbia, Canada the land was covered with glaciers that extended roughly to a point a bit north of today's Highway 2 Other glaciers abounded across many parts of the nation. A glacier of the same period extended beyond Seattle from Canada.
Then a climate change took place naturally, melting the glaciers. Over in Montana a lake called Missoula swelled with water. Meanwhile, the portion of the glacial ice between the North Cascades Mountains and eastward was stubborn and failed to melt as fast. Lake Missoula's ice barrier melted and fractured, permitting all the stored water to plummet roughly west and south along what is today part of the tributaries and the original Columbia River's ancient channel. This freezing and thawing went on several times before it all settled down for Lake Missoula. What a sight it would have been to see this torrent of water raging through the land.
Well, all went smoothly until the flood encountered the solid ice still present near today's Grand Coulee Dam and could not continue along the old Columbia River channel. Soooo, the river turned and headed south along an old earth fault that ran through the Grand Coulee (today's Banks Lake). It ripped open wide that fault through the layers of rock that now form the boundaries of Banks Lake, then fell over a plateau at Dry Falls (south of Coulee City) with a spectacle that was several times the width and descent of Niagara Falls. The flood quieted some but carved away a few more smaller, natural lakes before it again reached the ancient Columbia River channel not far from today's Hanford Project and turned to wreak havoc as sit headed for the ocean at today's Astoria. You who are geologists, bear with me in my simplistic tale of this unimaginable flood.
More about Steamboat Rock and this saga next time I share with you, probably next week. More new CR photos, too.
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