(bright music) (uptempo guitar music) ♪ Well the world has seven wonders ♪ ♪ That the travelers always tell ♪ ♪ Some gardens and some towers ♪ ♪ I guess you know them well ♪ ♪ But now the greatest wonder is in Uncle Sam's fair land ♪ ♪ It's the King Columbia River ♪ ♪ And the big Grand Coulee Dam ♪ - For many people, The King Columbia River begins and ends with Grand Coulee Dam.

The iconic 1930's project that produces cheap hydroelectric power to fuel homes, heavy industry, and harness water to irrigate Washington's crops.

The dam is the icon of the river, even to those who never visited.

(uptempo guitar music) It also damaged the world's greatest salmon runs, and disrupted cultures along the river that had existed there for millennia.

But Grand Coulee Dam is not the most impactful thing the Columbia has ever seen.

Grand Coulee Dam 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.

(uptempo guitar music ends) (playful bouncy music) The Columbia, or some version of it has existed for at least 17 million years.

(rousing music) 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 state from British Columbia, then out to the Pacific.

It is the greatest river in North America that flows west, fed by ice, snow melt, and tributaries, it draws from a vast interior region, from the Canadian Rockies and the Grand Tetons, to the depths of Hills Canyon, and rain soaked mossy rock.

(rousing music) But the river's course was warped along the way.

What bent the river?

Nick Centner is host of Cascade PBS's series, "Nick on the Rocks," where he explains northwest geology.

He suggested we meet here on the river to understand what skewed the Columbia's course.

Nick.

- Skip.

- Where are we, and why did you bring us here?

- Thanks for coming first of all.

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 that Columbia has not always been here.

- So, in ancient times it kind of ran diagonally, maybe across the state.

- Yeah.

Yeah.

- And then something put this big bend in it.

- You got it.

- And that was the lava.

- That was the lava.

The lava pushed the Columbia to this present location.

So yeah, 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.

(uptempo guitar music) - A major detour.

- You got it.

(uptempo guitar music) - If volcanic fire shaped the landscape, and changed the river, so too did ice.

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 Puget Sound in the west, and in the east, it extended into the Okanagan, 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 the lake.

We call it Glacial Lake Missoula, formed behind a 2000 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 set a flood of almost inconceivable size across the land, sweeping away everything in its path.

It dug Eastern Washington's channel scab lands, terrain that looks like it has been scoured raw by a galactic fire hose.

It scoured out Grand Coulee, it flooded the Columbia basin, and 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 floodwaters now made the gorge wider and deeper.

When the flood smashed through it 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, and then dropped them on the landscape.

Jay Harlen Bretz, a former Seattle high school teacher and dogged professional geologist, was fascinated by the unusual topography and geology of Eastern Washington.

(uptempo music) In the early 20th century, he carefully studied every nook and cranny.

Dry falls suggested a waterfall like Niagara Falls once flowed there.

But where did the water come from?

The evidence he believed, pointed to a landscape shaped by an ancient flood.

Many of his colleagues thought the idea was preposterous.

They resisted in part because they rejected a theory that 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 one epic flood sculpted the landscape, but that a succession of epic floods pulsed through, 40 or more of them over 2000 years, wiping out everything in their path, gouging out valleys, squaring away hills, scattering debris, exposing the bedrock, killing wildlife and human inhabitants in its path.

And Lake Missoula wasn't the only ice damned lake.

One in Northern Washington called Glacial Lake Columbia, formed when ice blocked Columbia for a time, sent it down Grand Coulee, the water that once spilled over Dry Falls.

The draining of that lake was the 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.

♪ But now the greatest wonder is in Uncle Sam fair land ♪ ♪ It's the King Columbia River ♪ ♪ And the big Grand Cooley Dam ♪ The river that indigenous people knew, that trappers, and traitors encountered at the dawn of the 19th century, now has 14 dams from its headwaters in BC, to its mouth at Astoria.

The transformation has been in the blink of an eye, compared to the epic forces that have shaped the river we've come to know over the millennia.

♪ Well she tore their boats to splinters ♪ ♪ But she gave men dreams the dream ♪ ♪ Of the day the Coulee Dam would cross ♪ ♪ That wild and wasted stream ♪ (uptempo guitar music)