The Channeled Scablands

Worldcon was, this year, in Seattle. We like to mix recreational and professional activities and, since Wendy and I are both rock and geology nuts, we decided to do something we’ve been talking about for years: visiting the Channeled Scablands. 

 

The scablands are an interesting combination in Eastern Washington and Oregon. To understand this, you have to go back about 14-27 million years ago. Then, a series of flood basalt eruptions roared up to become the Columbia River Flood Basalt Group (CRFBG.) These were big eruptions over the entire Columbia River area—thick to 1.8 kilometers (5900 feet) and covering a good chunk of both states. (Note the picture above with the added building for perspective.)  Some have attributed the eruptions to the same hotspot under Yellowstone. But that’s still debated.

 

One of the things that’s interesting is that this was relatively small and contained as flood basalts go. Both the Siberian Traps and the Deccan Traps were much, much larger. The Siberian Traps have been implicated in the Permian Extinction, aka, “The Great Dying”, where most species kicked the bucket. The Siberian Traps were implicated in the Cretaceous Extinction until the meteor hypothesis was more or less verified. Even now, there’s some evidence that the meteor might have reactivated the Deccan Traps, giving the world a sort of horrible one-two punch. 

 

The CRFBG didn’t affect the world as much as it’s two larger brothers, but it goes to show that these were big events. Even the smaller of them is enough to ruin your day for a few million years.

 

But the basalt cliffs in the picture above had many millions of years of getting covered with soil and sediment. It was largely buried until very recently.

 

Fast forward until only twenty thousand years ago when the Last Glacial Maximum—the last gasp of the Ice Age—happened. A set of ice sheets, kilometers thick, formed from the northeast corner of Washington all the way over Idaho and up into Canada. Glaciers melt back and advance with the seasons. Between 13,000 and 15,000 years ago, in the latter days of the Ice Age, these glaciers melted into Glacial Lake Missoula. Think of it as a Lake Michigan in Idaho’s back yard. These were all held back by an ice dam at a choke point of the Clarke River. Which gave all at once. 

 

The water tore down anywhere it found an avenue. It ripped over Dry Falls—I’ve heard it described as all of the waterfalls in the world times ten, but it’s a scale I can’t put my mind on. That said, that picture is just a little piece of it.

 

 

Some places, boulders got caught in place and spun in the current, causing potholes. 

 

 

Other places, it scoured out ripples from the stone. Or, in other places, it made gigantic sand ripples. Or dropped big, building sized boulders it had carried along. When it reached a choke point, and the water slowed down, it dropped sediment. This is why the Willamette Valey and valleys of Washington are so fertile. You can thank the Missoula Floods for your Washington apples.

 

This didn’t happen once. It didn’t happen twice. It happened in excess of a hundred times, at last count, from the ranger at Dry Falls park.

 

We spent several days in the area, looking at this stuff. Nothing like a good collection of geological features to make you feel small.

 

And, just to be clear that our executive thinks you’re too small to matter, here is a link on the current war on science. Or how He-Who-Shall-Not-Be-Named wants to control your universities. Or how Orange Voldemort isn’t interested in your dying in a heatwave.