Mossback’s Northwest: How the Columbia River got its curves - Anlık Haber

Well, the world has seven wonders, the travelers always tell
Some gardens and some towers, I guess you know them well
But the greatest wonder is in Uncle Sam’s fair land
It’s that King Columbia River and the big Grand Coulee Dam.

— “Grand Coulee Dam,” Woody Guthrie

For many people, the “King” Columbia River begins and ends with the Grand Coulee Dam, the iconic 1930s project that produces cheap hydroelectric power to fuel homes, heavy industry and harnesses water to irrigate Washington’s crops. The dam is the icon of the river even to those who never visit it. It also damaged the world’s greatest salmon runs and disrupted cultures along the river that had existed there for millennia.

But the Grand Coulee Dam is not the most impactful thing the Columbia has ever seen. The Grand Coulee is not even the biggest dam that has stopped or diverted its waters. The river we know today has been radically transformed by enormous forces we can hardly imagine.

The Columbia or some version of it has existed for at least 17 million years, but the river has been through cataclysmic changes both before and after humans arrived on the scene.

One of the most notable is how the river’s course has changed over time. The ancestral Columbia ran roughly diagonally across Washington from British Columbia then out to the Pacific. It is the greatest river in North America that flows west, fed by ice, snowmelt and tributaries it draws from a vast interior region — from the Canadian Rockies and the Grand Tetons to the depths of Hell’s Canyon and rain-soaked Mossyrock.

The Columbia River moving through Central Washington. (Wikimedia)

But the river’s course was warped along the way. What bent the river? We spoke with Nick Zentner, host of Cascade PBS’ series Nick on the Rocks, where he explains Northwest geology. He suggested we meet on the river to understand what skewed the Columbia’s course.

Nick explains: “This is Chelan and the Columbia River is flowing north to south right by the town, and what’s cool is that both sides of the river are not matched geologically. So east of the river there’s this basalt lava 16 million years old. On the west side of the Columbia it’s not lava at all, it’s this migmatite, which is 160 million years old, from 20 miles below the surface of the Earth. So the idea is the Columbia has not always been here … the lava pushed the Columbia to this present location.”

Nick goes on: “Before 16 million years ago we’re quite confident that the Columbia River came out of British Columbia and flowed essentially straight to Tri-Cities in southern Washington. But here comes this molasses erupting out of a volcano in northeastern Oregon, and there’s three miles thick of this basalt lava that just buried the mountains and pushed the Columbia River right to this very spot.

But there’s still more to the story. “If volcanic fire shaped the landscape and changed the river, so too did ice,” adds Skip.

Over the millennia, ice ages came and went. The last Ice Age began to recede some 17,000 years ago. The vast Cordilleran Ice Sheet came down from the north and was thousands of feet thick. It had pressed south into the Puget Sound region in the west, and in the east it extended into the Okanogan, the Spokane area, northern Idaho and Montana. As ice advanced and receded, it altered the landscape. The ice sheet blocked and unblocked rivers, including the Columbia. Around 15,000 years ago, the massive ice sheet blocked the Clark Fork River in Idaho, and a lake — we call it Glacial Lake Missoula — formed behind a 2,000-foot-tall ice dam. The lake is believed to have had a water volume as great as that of Lake Ontario and Lake Erie combined. But the dam breached and sent a flood of almost inconceivable size across the land, sweeping away everything in its path.

It dug Eastern Washington’s Channeled Scablands — terrain that looks like it has been scoured raw by a galactic fire hose. It scoured out the Grand Coulee, it flooded the Columbia basin. In places new lakes formed where floodwaters backed up at choke points like Wallula Gap. The Columbia had taken millennia to burrow a gorge through the Cascade Mountains, but the flood waters now made the gorge wider and deeper. When the flood smashed through and spurted out the west end, it had a wall of water 500 feet high. It raced down Oregon’s Willamette Valley all the way to Eugene carrying enormous boulders stuck in icebergs, floated hundreds of miles from the nearest ice sheet, then dropped them on the landscape.

The floods that formed the great basin. (National Parks Service)

J. Harlen Bretz, a former Seattle high school teacher and dogged professional geologist, was fascinated by the unusual topography and geology of Eastern Washington. In the early 20th century, he carefully studied every nook and cranny. Dry Falls suggested that a waterfall like Niagara Falls had once flowed there, but where did the water come from?

The evidence, Bretz believed, pointed to a landscape shaped by an ancient flood. Many of his colleagues thought the idea was preposterous. They resisted it in part because the theory sounded so Biblical instead of adhering to a more gradual shaping of the landscape through time and erosion.

What is accepted now is that not just one epic flood sculpted the landscape, but that a succession of epic floods pulsed through — 40 or more over about 2,000 years — wiping out everything thing in their path, gouging out valleys, wearing away hills, scattering debris, exposing the bedrock, killing wildlife and human inhabitants in its path.

And Lake Missoula wasn’t the only ice-dammed lake. One in northern Washington, Glacial Lake Columbia, formed when ice blocked the Columbia and, for a time, sent it down Grand Coulee — the water that once spilled over Dry Falls. The draining of that lake was a source of flooding too. The extent of the floods and their various sources is still being studied, some perhaps far older than the Missoula. Whatever happened, it was catastrophic and complicated — a puzzle geologists are still putting together.

So the Columbia River was altered drastically before humans altered it in ways that Woody Guthrie celebrated in song. The river that Indigenous people knew, that trappers and traders encountered at the dawn of the 19th century, now has 14 dams from its headwaters in B.C. to its mouth at Astoria.

This transformation has been in the blink of an eye compared to the epic forces that have shaped the river we know over the millennia.

She heads up the Canadian Rockies where the rippling waters glide
Comes a-rumbling down the canyon to meet that salty tide
Of the wide Pacific Ocean where the sun sets in the west
And the big Grand Coulee country in the land I love the best.
                         — “Grand Coulee Dam,” Woody Guthrie

Topics: <a href=”https://www.cascadepbs.org/environment-0″ hreflang=”en”>Environment</a>, <a href=”https://www.cascadepbs.org/history” hreflang=”en”>History</a>, <a href=”https://www.cascadepbs.org/mossback” hreflang=”en”>Mossback</a>, <a href=”https://www.cascadepbs.org/mossbacks-northwest” hreflang=”en”>Mossback's Northwest</a>, <a href=”https://www.cascadepbs.org/multimedia” hreflang=”en”>Multimedia</a>, <a href=”https://www.cascadepbs.org/video-0″ hreflang=”en”>Video</a>

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