It's not fair, but I don't spend much time in Portland, Oregon. It's not that I don't like Portland, I just don't know it because the logistics of my normal travels rarely allow me to stop there. We are always three or four hours away from our destination and worried about getting through town without getting stopped in one of Portland's legendary traffic jams. But on our way to meet our students in Seattle for our field studies trip to British Columbia we decided to stay in Portland, ostensibly to get nice pictures of Mount Hood. We were moving along Interstate 205 and the traffic wasn't too bad, and saw a wayside viewpoint and pulled off. It was there that I discovered for the first time the work of Tallapus (Coyote) to help the Clackamas people procure a secure food supply of salmon and lamprey: Hyas Tyee Tumwater, otherwise known as Willamette Falls. It's the second largest waterfall in the United States after Niagara. It's 1,500 feet wide, drops around 40 feet, and has a flow that averages about 30,000 cubic feet per second.
What? You've never heard of it? Neither had I. I would have thought that the second largest waterfall in the country would have attracted a bit more attention among travelers, but there are reasons that it is not all that familiar. Some of the reasons go right to the heart of cultural conflicts between European colonizers and the original inhabitants of the region.
The Willamette River is a major tributary to the Columbia, providing around 10-15% of its total flow. Major rivers don't tend to have waterfalls unless unique geological conditions exist. And the story of the Willamette is pretty wild. The river is one of the few north-flowing rivers in the country, following a geologic trough related to the actions of the Cascadia Subduction Zone. In other words, the valley of the Willamette River was not carved by the Willamette River. The valley is weird in some other ways...there are fine silt layers covering much of the valley floor, but scattered here and there are hundreds of gigantic boulders weighing as much as 170 tons. Boulders that came not from the adjacent Coast or Cascades Ranges, but from Montana and Idaho! How can these things be explained?
Between 15,000 and 13,000 years ago, the Pleistocene Ice Ages were beginning to wane, but an edge of the gigantic ice sheet that covered most of Canada flowed into Idaho and Montana and blocked of a major river drainage. A massive lake, now called Lake Missoula, formed behind the ice dam. The volume of the lake grew to 500 or 600 cubic miles of water, but then the ice dam destabilized and collapsed, sending a massive flood amounting to about ten times the combined flows of all the rivers on Earth racing across the plains of eastern Washington. The raging waters careened through the Columbia River Gorge at depths of hundreds of feet and the flows backed up into the Willamette River Valley. The muddy waters settled out, forming the silt layers covering the valley floor. The boulders arrived encased in icebergs in the turbulent currents. As the ice melted the boulders dropped out. The ice dam re-formed dozens of times and floods occurred at intervals of 50 or 60 years for around 2,000 years.
As the floodwaters receded the lava flows were exposed and then eroded by the waters draining from the Willamette. The ledges of lava became Willamette Falls.
|Source: By M.O. Stevens - Own work, CC BY 3.0, https://commons.wikimedia.org/w/index.php?curid=6816704|
Most of these abuses are not visible from the overlook at Interstate 205. One wishes that with most of the ugly factories abandoned that the river and falls might be returned to a state resembling the primeval river. There are plans to "develop" the site with river walks and interpretive signs, but of course in the current culture of capitalism, also businesses and tourist attractions. It its own way tourism is a resource like any other, a commodity to be exploited.
In the end, I hope the stories will remain. The story of how Tallapus scooped out part of the river to slow down the migration of the salmon and lampreys so the people could catch some of them. And the story of how awesome, almost incomprehensive forces were unleashed by nature to form the falls through lava flows, glaciers, and gigantic floods.
|Source: Army Corps of Engineers|