Dry Falls

Who wants to visit a dry waterfall, especially this one which has been dry for thousands of years? Perhaps you might. It's the story behind the creation of the falls that makes it a place to see. Dry Falls had a rim measuring 5.6 km and dropped 122 metres. Niagara Falls has a rim that is only 1.6 km long, and its drop is about 50 metres. It would look very tiny in comparison. When you visit Dry Falls your first wish is to see it flowing. Fortunately that period in the development of North America is gone now, until the next ice age, at least.

The story begins with a tongue of ice from a continental glacier pushing out of Canada. It plugged the Clark Fork River with a thick dam of ice. The water behind the dam spread back into Glacial Lake Missoula, which rose 600 metres. Ice does not make a very good dam, and when the ponded water got high enough the pressure caused the ice to float. Immediately, all twenty five hundred cubic kilometers of water in the lake headed across the landscape in a giant flood. It would be similar to spilling a drum of water on your table at supper. Water went everywhere.

On the way it ripped and tore at the layers of basalt, tearing huge chunks from their beds and tumbling them along like battering rams. Researchers suggest water speeds of up to 100 kmph. Mere earth and gravels were no obstacles and these moved great distances, settling out wherever the speed of the water slowed sufficiently. The rapidly eroding water cut deep gorges or canyons, called coulees in the country where the falls was created. The area stripped of its topsoil, and gouged and scoured, is called the scablands of Washington.

Ahead of the raging flood was the narrow Wallula Gap, which was only large enough to handle one-fifth of the flow. Behind it, water flooded back into valleys until it was more than 180 metres deep. A visit to Crown Point State Park at the entrance to the Columbia Gorge will show you a point 210 metres above the river that would have been submerged during this time. It is estimated that the ice dam event repeated between 40-60 times, as learned by looking at the number of different sediments created in these valleys. It is also possible to look at the number of benches eroded into the hills above glacial Lake Missoula.

Just upstream from Dry Falls, another waterfall was likely 250 metres high, but the rushing waters cut through the hill and turned the high falls into a cascade of rapids. We have all observed ripple marks in the sand in rivers, and on beaches. Just try to imagine ripple marks that are as high as good-sized hills. The highway leading through this area has a set of switchbacks where the highway climbs over one of these ripple deposits.

Dry Falls State Park provides the viewing area for Dry Falls. The bottom of the coulee was dry for centuries, but now there are pools of water that accumulate from seepage through the rock from a reservoir that has been created above the falls. A look across the coulee shows you the width of the gorge that the raging waters cut from the plateau.

A trip across the Washington State Scablands provides a striking opportunity to see the effects of nature on a rampage. You will find the drive along the Clark's Fork River very scenic, lots of trees and hill, and the beautiful winding river at your side.