More geology

This is Dry Falls, in central Washington. The previous post mentioned the Missoula floods. Dry Falls was a major player. First, the Ice Age glaciers surged across the plateau to the northwest of this area, blocking the course of the Columbia River. Eventually, the Columbia was diverted down Grand Coulee and over Dry Falls. This occurred 15-13 thousand years ago. Under usual conditions during that period, the Columbia poured over the precipice here, dropping 350 feet in a torrent three miles wide, making Niagara Falls look like a ripple. But during the Missoula floods, an ice jam in the Idaho panhandle repeatedly gave way, releasing glacial Lake Missoula all at once. This was a fairly significant event; it's been estimated that the rapid emptying of the lake released a volume of water ten times larger than the combined flow of all the current rivers in the world! This is so great that it's been calculated that during the Missoula Floods Dry Falls was not so much a waterfall but a monstrous torrent beyond comprehension; a whitewater rapid probably 500 feet high! The spectacle boggles the imagination. And it happened over and over, about 36 times by recent estimates...over a period of 2000 years.

Here's a shot of Grand Coulee Dam. Now, the amazing thing about what the ice age glaciers did, diverting the Columbia River into Grand Coulee, is that the coulee is about 550 feet ABOVE the river level at the dam! This means, of course, that the glaciers dammed the river to a depth considerably deeper than that; then, during the Missoula floods, several hundred feet of additional water entered glacial Lake Columbia! Absolutely incredible.

It would have been cool to see all this; but, dudes, the ice age was harsh! Imagine hundreds of thousands of square miles of the US rendered uninhabitable under thousands of feet of ice, with large areas just south of the ice changed to tundra by cold, dry winds off the glaciers. Then add saber toothed tigers, dire wolves, cave lions, short faced bears, the occasional mammoth running amok; then take away such modern conveniences as ESPN, the internet, and In-and-out Burger. The tribulations of global warming are minor by comparison!