Wednesday, July 6, 2011

A Convergence of Wonders: Day 5, In the Land of the Great Flood


In the movie "A River Runs Through It", the narrator ends with the following, one of my favorite quotes in any movie...
Then in the Arctic half-light of the canyon, all existence fades to a being with my soul and memories and the sounds of the Big Blackfoot River and a four-count rhythm and the hope that a fish will rise. Eventually, all things merge into one, and a river runs through it. The river was cut by the world's great flood and runs over rocks from the basement of time. On some of those rocks are timeless raindrops. Under the rocks are the words, and some of the words are theirs. I am haunted by waters.
Because Norman Maclean's father was a Presbyterian minister in the 1920s, and his preaching and teaching was one of the ongoing themes in the book and movie, I assumed the referred-to flood was Noah's, but when I picked up the book, I was surprised to find that he was actually speaking about the Spokane Floods. My appreciation and respect for Norman Maclean jumped up many notches.

Geology, a science that embraces change more than any other, was caught in a form of stasis at the beginning of the 1900s. Geologists embraced the principle of uniformitarianism, the idea that we can learn of past processes by looking at those that are active today. It is in fact the founding principle of the science, but a hundred years after adopting it, geologists were trapped into a mental construction that required that all processes were the same, and that they operated at the same rate as they do today.

J Harlan Bretz was a high school science teacher in Washington state (later a professor in Chicago). He was mystified by elements of the landscape across the drainage of the Columbia River, especially a region that he called the Channeled Scablands. Numerous dry river channels and small depressions cross the high plateaus of basalt, carving up the windblown silt prairies into islands of fertile soils (the Palouse Soils). I posted an aerial photo of some of these silt islands here.  In places, the dry channels were in deep canyons separated by long-dry waterfalls (the Coulees).
Bretz wanted  to know how this landscape...
...became this one...
Conventional geology explained the dry river channels as having formed as a result of erosion by rivers draining off the melting glaciers of the last ice age, since the vast continent-size glaciers had terminated only a short distance north and east of the region. But the river hypothesis couldn't explain the ponds among other things; rivers don't normally form isolated lakes, except in cutoff oxbows. Bretz began to study the strange landscape, operating without the benefit of aerial or satellite photography. He developed a startling hypothesis: the channels and scablands had formed during a giant flood or series of floods of short duration.

When he published papers on the subject in the 1920s, geologists were aghast. Giant floods covering the landscape to a depth of hundreds of feet were not a part of normal geologic thinking. It smacked more of religious catastrophism. And Bretz couldn't say where the floods had come from. But the evidence accumulated, and after only a few decades, geologists came to accept the model. Luckily, Bretz lived long enough to see his ideas accepted, and he was ultimately given geology's highest from of recognition, the Penrose Medal (geologists don't get Nobels). Other geologists even found the source of the flood, a gigantic lake in Montana (Lake Missoula) that formed as the tongue of a glacier blocked a river drainage. The floods occurred when the unstable dam collapsed, unleashing cubic miles of water across the Washington landscape.
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That's where we were headed on the fifth day of our journey in the Pacific Northwest.

The rains of the previous day were gone and forgotten. The day was bright and clear as we headed north out of Yakima. Our first stop was Central Washington University in Ellensburg where we talked with the archaeologists who have been studying dating of human teeth, and who have been excavating the Wenas Creek Mammoth Site. Pat Lubinski took us on a tour of the lab where the fossil specimens have been laid out (the giant femur in Dr. Lubinski's arms is a lightweight cast, in case you were wondering).
In case you wonder about how we keep our army of students moving and fed, here is a shot of our shopping trip at the big grocery store in Ellensburg. There was a Starbucks, so the students were content.
At Vantage, we had a chance to see some pillow basalts and palagonite clay that formed when some of the plateau basalts flowed into a lake or swamp around 15-16 million years ago. The quartz-rich sands at our feet were deposited by swirling eddies during the Spokane Floods. Quartz is rarely seen in basalt; it was carried to the area from elsewhere.
Vantage also provided us a nice cross-section of the basalts that underlie the Columbia Plateau. The vast outpouring of lava covered tens of thousands of square miles of eastern Washington, Oregon, and northeastern California. Some of the flows traveled several hundred miles from vents near Spokane all the way to the Pacific Coast.
 At Lenore Lakes there were cliffs and deep valleys, but no river, just groundwater-fed lakes.
There were also some beautiful flowers! Does anyone want to identify it for me? It reminded me a bit of our Mariposa Lilies back in the Sierra Nevada.
We were in one of the coulees, the rapidly eroded canyons that formed in the Spokane floods. Eddies in the flood scoured out the columns, but not the overlying entablature rocks, forming deep alcoves. The alcoves have been used for thousands of years by humans as temporary shelters. In the 1930s, a hollow in the cliff nearby proved to be the mold of a rhino-like mammal that had died and then was covered by flowing lavas.
Dry Falls State Park is one of the most spectacular monuments to the vast floods that crossed Washington on the headlong rush to the sea. There was a 300 foot high waterfall here, miles across, which would have been nearly invisible in the deep waters (the photo at the beginning of the post is the main view of the falls). The scale of the event is nearly unimaginable.
Just upstream is the Grand Coulee, an even deeper channel cut by the floodwaters. Dam(n) engineers realized the potential for water storage, and constructed Banks Lake to fill it. The road is spectacular.
We made a brief stop at Grand Coulee Dam ("Roll on, Columbia roll on" - did anyone else sing the Woody Guthrie song in grade school?). I seem to recall reading that this is the biggest chunk of concrete anywhere in the world. I haven't fact-checked this claim.
Then it was a run across the scablands and the Palouse prairie to Spokane and our camp at Bowl and Pitcher State Park along the nearly flooding Spokane River. It was a very nice grassy campsite, and a comfortable night. Tomorrow we would be seeking the source of the floods in Montana. And the glaciers of Glacier National Park.

3 comments:

Gaelyn said...

Dry falls just blows me away. It is easy to imagine a Huge waterfall there. Hope you saw the horses sculpture at Vantage.

Ben Budge said...

Nice post, The Channeled scab-lands and Columbia Plateau are my stomping grounds! Its good to see that they are getting some love. I received my undergrad at the University of Idaho and am reminded of the many field trips out into the area.

JWhite said...

Your lily is a sagebrush mariposa :)

I enjoy your words and the photos are great.

In honor Dr. Bretz, I stubbornly refer to the floods as Bretz Floods, and only wish they weren't called by other names like Missoula Floods.

I live near Goldendale and have noticed pillows with palagonite on the Columbia Hills, the southernmost anticline of the Yakima fold belt. The pillows occur on Old Hwy 8 on Goodnoe Hills, Hwy 14 east of John Day dam, Hwy 97 above Maryhill, the Lyle-Centerville Hwy, and other road cuts. They are overlaid by loess at Hwys 8, 14, & 97, and by what looks like a pyroclastic flow on the Lyle-Centerville Hwy. I've been trying to find out if those pillows are from a local flow in the Simcoe Volcanic Field, Saddle Mountains flood basalt that plowed into the Mabton interbed, or from Wanapum flood basalt plowing into Vantage/Latah interbed. I'm leaning toward Saddle Mountains flood basalt, but am having trouble finding literature on Columbia River Basalt Group stratigraphy for this area. I ordered some more geologic maps & literature. You can probly tell I have like one year of college geology, but I really "dig" it. Anyway, the pillows/palagonite in your photo look just like the ones I see many miles from Vantage. Do you know which flow resulted in this widespread, intermittent pillow formation? Thanks again for your interesting blog.