Channeled Scablands: Eastern Washington, Mega Floods and the Mars Connection
Windswept spaces, high basalt columns, dry waterfalls, channels and coulees. These are not small spaces that we are talking about here. The Channeled Scablands are a desert terrain formed by a combination of lava flows, huge floods, canyons gouged out by glaciers and strong winds that continually sculpt the earth.
If you drive from Seattle to Spokane along I-90, you will miss a large portion of the strange geologic formations and canyons that are a result of the roaring waters from the Glacial Lake Missoula floods that poured across this landscape about 13,000 years ago.
In different parts of the world, a coulee means different things. In Eastern Washington, a coulee is no mere channel for a river. It’s a wide canyon or ravine that is large enough that carved out does not begin to describe the scale of distance here. The State of Washington has designated a Coulee Corridor National Scenic Byway. This is a 100 mile stretch of road that you can follow to see the diverse geologic formations that are a by-product of this massive flood. But the actual area that encompasses the Scablands is conservatively estimated at 1,500 and 2,000 square miles (3,900 and 5,200 km²).
What’s truly amazing is that the theory of how this land developed into this barren landscape was first proposed in the early 1920s by J. Harlan Bretz before aerial photography existed. And his proposed theories kicked off a forty-year debate by the leading scientists of his time. You can read about the discovery and debate in the book, “Bretz’s Flood: The Remarkable Story of a Rebel Geologist and the World’s Greatest Flood” by John Soennichsen.
If you have limited time, but want to experience some of this amazing landscape, you can take US-2 West from Spokane for 95 miles and take WA-17 to Dry Falls, a remnant of what was once the largest waterfall known to have existed on earth. What remains is a stark cliff that is 400 feet high and 3.5 miles long. At Dry Falls, you can visit the interpretive center that not only tells the history of this land, but provides a wall of windows over the precipice that gives you a view of the surrounding landscape.
Okay, you might agree this is pretty amazing geology, but where’s the Mars connection?
In 1978, Victor R. Baker, in a paper, noted the similarity between the Channeled Scablands and the flood channels of Mars. And then in 2009, discovery of columnar jointing in Martes Valles, Mars (Milazzo et al., 2009) has strengthened the relationship between the Channeled Scablands, where jointing is readily observable in the Columbia basalts, and our Martian neighbor. Scientists have visited Eastern Washington to gain more perspective on other planetary features that may similarly be found on Mars.
- For a full itinerary to check out the Channeled Scablands in Eastern Washington, see the Coulee Corridor Scenic Byways trip details page from the State of Washington.
- Explore the Channeled Scablands using Nova’s interactive map.
by Judith Herman