‘National Geologic Trail’ Would Tell the Tale of Ice Age Floods

Dry Falls lives up to its name. Not a drop of water cascades down the 500-foot cliffs at this arid, rocky place near Grand Coulee Dam.

But 15,000 years ago, at the end of the last Ice Age, catastrophic waters roared over this former waterfall. The spectacle dwarfed Niagara Falls, its power 10 times greater than the force of all the world’s rivers combined.

The cataclysmic water scoured away the soils of eastern Washington and carried house-sized boulders from Montana as far away as Oregon.

Now Congress is considering whether to create a “national geologic trail” that would stretch from Missoula, Mont., to the Willamette Valley in Oregon and tell the story of the Ice Age floods.

The auto route would be managed by the National Park Service and follow the path of the floodwaters through four states. It would be the first such route in the country dedicated to the geology of an area rather than the human history, and backers of the proposal say it has economic benefits.

“By supporting economic development, creating jobs in local communities and preserving our heritage for generations to come, this trail will be an outstanding step forward for the region,” said Sen. Patty Murray, a Washington Democrat.

Rep. Doc Hastings (R-Wash.)introduced a bill last month that would give the park service the authority to create the route.

Scientists believe the floods occurred repeatedly, perhaps as many as 50 times, between 17,000 and 13,000 years ago. A lobe of continental glacier would block the path of the Clark Fork River near the Idaho-Montana border and back up water hundreds of miles into the Bitterroot and Flathead valleys of Montana. Water towered 950 feet above the present city of Missoula, where ancient shorelines are still etched into the sides of hills surrounding town.

Ice makes a poor dam. Eventually the lake broke free, sending 2,900 square miles of water pouring across northern Idaho and eastern Washington. Floodwaters hit the Columbia River near present-day Wenatchee, Wash., and roared west.

The water tore fertile soil from thousands of square miles of land and deposited it in Oregon’s Willamette Valley. Rushing water gouged giant coulees and made waterfalls 3 miles wide.

Flood features are visible from space and have been used by scientists as they study comparable sites on Mars.

Geologist J. Harlen Bretz of the University of Chicago came up with the theory of catastrophic floods that shaped the landscape in a matter of days.

His theory, introduced in 1923, was pilloried for decades by those who followed the conventional wisdom that geologic events occurred gradually, not all at once. Bretz was called a dunce and a heretic, but over time his work became widely accepted.

The route would follow the models of the Oregon National Historic Trail, the Lewis and Clark National Historic Trail and the Nez Perce National Historic Park, using road signs and interpretive displays to guide visitors.

No land would be acquired for the project.

“There are some folks who got all fired up that this was a 7-million-acre land grab by the National Park Service,” said Dale Middleton of Seattle, president of the Ice Age Floods Institute, which has pushed for the auto route for years.

But the current proposal ties together only existing state and federal lands. The park service would provide a central administrative office and a small staff, Middleton said. The bill calls for spending no more than $500,000 to create the trail.