by Bob Gunter
The pale sun rolled back the mist like a scroll and the surface of the monstrous lake slowly became visible in the morning light. The swirling water and ice covered much of the land except for some of the higher mountains. Around the lake there was sparse vegetation growing among the windblown sand dunes through which greenish-gray rivers cut. Giant cliffs and walls of ice could be seen far on the northern horizon.
The lake was growing at all times and covered an area the size of Lake Erie and Lake Ontario combined. Lake Missoula stretched for hundreds of miles across western Montana. An ice dam standing about 3,000 feet high was the plug, which held the huge volume of glacial water in place. The dam was located where the Clark Fork River meets Lake Pend Oreille in North Idaho.
Indian Point on Lake Pend Oreille, Sandpoint Idaho
Click photo to enlarge
Nothing, on the surface, gave any indication as to what was going to transpire at the lake over 12,000 years ago, but at the base a small stream of water flowed from the ice. The stream grew until more and more water came gushing out and the stream grew larger. With a thunderous roar of breaking ice and rushing water the ice dam collapsed and in less than 48 hours Lake Missoula was drained. The force of the 2,000-foot wall of water shooting out of Clark Fork Canyon measured 10 times the combined flow of all the known rivers of the world. The ground shook as between 500 and 600 cubic miles of glacial water roared through Cabinet Gorge on its way to the Pacific Ocean. The torrents of water raced forward at the speed of 70 miles per hour stripping away soil, moving large boulders, and creating deep canyons, or coulees, in the bedrock. The paths of the great flood converged in the Pasco Basin. There the rush of water was slowed by a narrow passage called the Wallula Gap. This narrow gap caused the waters to back up and a 1,200-foot lake was formed.
The cause of the largest, scientifically proven, flood known to man was due to the rapid drainage of Glacial Lake Missoula. During the ice age a great lobe of the Cordilleran ice sheet in Canada had moved down the Purcell Trench into Lake Pend Oreille basin. This resulted in the Clark Fork valley acting as a dam and creating a glacial lake, which covered about 3,000 square miles in western Montana. The breaking of this dam resulted in the flood leaving its mark across Montana, Idaho, Washington and Oregon. As the floodwaters engulfed the rivers in an area it would push back up the major rivers. Lewiston was covered with water when it pushed back up the Snake River. Wenatchee and the area around Yakima were covered by water. Coeur d'Alene, Idaho, Spokane,WA and Portland, Oregon were inundated by the raging floodwaters.
There is evidence that the great floods of the Northwest occurred many times and played a big role in shaping the great Northwest. The scabland of Eastern Washington, the Columbia basin with its stark cliffs and waterfalls, the numerous gravel deposits and the huge potholes found in the path of the flood give a picture of its force and magnitude. The landscape of Rathdrum, Idaho, Coeur d'Alene and Spokane, as well as, the Spokane aquifer are results of the glacial floods.
The scientific data that confirms the fact that this part of the Northwest was partly formed by a cataclysmic flood comes from Professor J. Harlen Bretz. He was a professor at the University of Chicago and in 1923 began a series of papers explaining the origin of the Channeled Scabland in Washington State. His view that large scale flooding had caused the dry channels and coulees so evident in Washington was rejected by the geologists of his day. Over time, with help from further scientific evidence, the ideas promoted by Bretz have been accepted.
All photographs have been used with permission of the Bonner County Museum. |
