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.
Every since the eroding flood steepened the valley walls, volcanic rock has been sliding in a series of giant landslides. Sometime between 750 and 1,300 years ago half of Table Mountain on the north side of the Columbia River broke way in a colossal slide that completely blocked the river. It was probably triggered by an earthquake. The old river channel lay beneath the mass. A lake some 90 miles in length rapidly formed behind the blockage.
In time, measured in centuries, the water forced its way around, through and over the dam at the relatively thin southeast end of the slide (Oregon). It is possible that water eventually tore out a great portion of the dam, creating the wide bridge.
According to the Indian legend, about 750 years ago the Great Spirit created “a place to cross the river without getting your feet wet.” Later, angered by the warring tribes on both sides of the river, the Great Spirit destroyed it and the rocks fell into the Columbia River.
Somewhere between that time and the coming of the first white man, the dam and bridge gave way and the lake receded. At the point where the river forced its way through the landslide, big boulders were blasted out of the way to aid navigation and the Bonneville Dam backwaters covered the cataract.
Not far downstream a silver, man-made bridge now spans the Columbia River near Cascade Locks, Oregon (coordinates). There have been other massive slides along the Columbia, but none that have had the impact of the one called the Bridge of the Gods.
Instructions for logging waymark: A photograph is required of you (or your GPS receiver, if you are waymarking solo) and the Bridge of the Gods.