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The Biggest of the Lake Missoula Floods
The Glacial Lake Missoula Floods were some of the largest known floods on earth. This is a website about the largest of those floods. For over 40 years people refused to believe in the Lake Missoula Floods. The evidence; however, was overwhelmingly clear and now it is accepted that over 500 cubic miles of water suddenly burst out of the Clark Fork River in northern Idaho, and rampaged across Central Washington and down the Columbia River Gorge to the Portland/Vancouver area. It briefly
filled up the Tualatin Valley to the west of Portland; the Clackamas River Valley southeast of Portland; the Willamette Valley south of Portland as far as Eugene; and the Lewis River Valley north of Vancouver, Washington; to nearly 400 feet above sea level. Then it rushed out to sea just as quickly as it had come in.
Any geologic event this devastating will leave lasting effects on the countryside. The cliffs, truncated hillsides, huge gravel bars, flood channels, flood boulders and iceberg (glacial) erratic rocks that remain today are the subject of this website.
There is far more that we do not know about the Lake Missoula Floods than we do know. One lone geologist, J Harlen Bretz, first recognized the evidence about 100 years ago but the geologic establishment has only accepted it in the last 50 years. The large areas involved (parts of four states and one province) make a thorough study difficult and time consuming. In most cases, the researchers work within a day’s travel of where they live. Thus, no one person knows the big picture as well as they like. Instead, we have many people with good understanding of individual pieces of the puzzle, much like the proverbial blind men describing an elephant.
Every day there is more research and more dissemination presenting a fuller picture to a fascinated public. What we are learning noware the effects it left behind. As with any detective story, it will take time and effort by many people to uncover the whole Lake Missoula Flood story.
Here I will share some of what I am learning about the greatest of the
Lake Missoula floods, the Giga Flood.