The Channeled Scablands

An ice Age Legacy

by: Rich Leon

Most eologist J. Harlen Bretz of the University of Chicago first coined the term, “channeled scablands,” in the 1920s when he made a comprehensive study of the region and proposed that its erosion was the result of a gigantic, prehistoric flood.

The territory Bretz studied extends from Spokane west to the Columbia River near Vantage and south to the Snake River near Pasco. The Scablands are marked by long channels carved into the bedrock called coulees. The most expansive is Grand Coulee which is sixty miles long.

The Scablands feature remote canyons, basalt cliffs, sagebrush plateaus and one of the largest waterfalls in the nation—Palouse Falls.

During the last Ice Age, 10,000 to 20,000 years ago, an ice dam formed to wall off Lake Missoula in western Montana. The vast body of water covered 3,000 square miles and contained as much water as Lake Erie and Lake Ontario combined.

When the weight of the water caused a leak at the base of the ice wall, it created one of the most massive floods in world history. Millions if not billions of gallons of water engulfed the landscaped from Montana, to Northern Idaho to Washington State and on to the coast of Oregon where is settled in the Pacific Ocean.

The flood washed away most of the topsoil, all the way down to the volcanic basalt bedrock and created the coulees we see today. Geologists believe the flood events repeated as many as 40 times over the centuries and only stopped when the Ice Age ended.

Bretz theories on the floods were controversial when he published them in scientific papers in 1923. His colleagues thought he was crazy until further study and NASA’s satellite imagery confirmed his concept in the 1970s. It clearly revealed a network of channels carved out by the series of mega floods.

Most of the Scabland is public land managed by the Bureau of Land Management. Unlike other state and federal land, the BLM has yet to charge fees to make use of the Scablands. And information about the region is available at the BLM office at 1103 N. Fancher Road in Spokane Valley.

If you set out to explore the Scablands, bring your camera. Spring in the canyons and buttes is ablaze with wildflowers. But spring also awakens the rattlesnake population, so beware.

Heat is another foe to avoid in the Scablands. Most of the land has very little shade, and spring temperatures can climb into the 90s with little warning. That coupled with low humidity can lead to heat exhaustion. So carry plenty of water, wear a wide brimmed hat and use plenty of sunscreen, even on overcast days.