Missoula Flood & Multnomah Falls, Oregon
Posted by: 
Rose Red
N 45° 34.597 W 122° 07.040
10T E 568866 N 5047387
After the Missoula Flood, the drastically eroded valley walls ended in very steep vertical slopes. It created one of the greatest concentrations of high waterfalls in North America. Multnomah Falls is the largest and best known of these waterfalls.
Waymark Code: WM16X3
Location: Oregon, United States
Date Posted: 02/05/2007
Views: 109
More than 15,000 years ago the Missoula Flood, the largest and most powerful scientifically documented freshwater flood to occur on earth, happened in the Pacific Northwest.
During a period of several thousand years a single large flood, a few, or possibly as many as 100 of these floods scoured the 600-mile path when the glacial ice dam repeatedly reformed, the lake filled up again, and the ice dam broke again. Each flood was separated by decades or centuries.
Before the flood, the Columbia River valley walls sloped gently down to the river. The powerful flood scoured the landscape of vegetation, removed up to 150 feet of topsoil and deeply eroded its volcanic bedrock on both sides of the river. After the flood, the drastically eroded valley walls ended in very steep vertical slopes.
It created countless cascades and one of the greatest concentrations of high waterfalls in North America, especially when the snow is melting in the spring and early summer. Multnomah Falls is the largest and best known of these waterfalls. The water drops 542 feet (Upper Falls) and 69 feet (Lower Falls) through a vertical slot it eroded since the last flood passed.
Instructions for logging waymark: A photograph is required of you (or your GPS receiver, if you are waymarking solo) and Multnomah Falls.