The Glacial Lake Missoula Floods were some of the largest known floods on earth. During the last ice age 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 to the Portland and Vancouver area. It briefly filled up all the valleys that fed into the Columbia and Willamette Rivers in Northwest Oregon and Southwest Washington to nearly 400 feet above sea level. Then it rushed out to sea nearly as quick as it had come in.
Any event this huge will leave lasting effects on the landscape. The cliffs, truncated hillsides, gravel bars, flood channels and boulders that remain today are what this website is about.
One lone geologist, J Harlan Bretz, first recognized the evidence about 100 years ago. What we are learning now are the effects it left behind in the lower Columbia region. As with any detective story, it will take time and effort by many people to uncover the whole Lake Missoula Flood story.
Here we will share some of what we have discovered about the greatest of the Lake Missoula Floods; the