Several recent posts have highlighted eastern Washington, a region I visited the last week or so of May to scout and photograph. While the Palouse in the southeast is quite famous as a landscape photography destination, I made a point to visit an area that is just as famous but with a different group of people altogether. The Channeled Scablands cover a rather large region in central Washington with spectacular erosional features. It’s unusual geography records the largest flood we know of in earth history. For this reason the Scablands are on most geologists’ bucket lists.
The Missoula Floods came racing down through this area towards the end of the last ice age. The last one happened about 12,000 years ago, but there were dozens of similar deluges stretching back thousands of years before that. The floods were triggered when an ice dam across the Clark Fork River in western Montana burst and the enormous Lake Missoula drained catastrophically. The water cascaded down through what is now eastern Washington, down the Columbia River to what is now Oregon, and on to the coast. Some of the larger floods equaled more than 10 times the annual flow of all the rivers in the world.
As you might expect with that much water, the evidence of its passing is still around. Now it seems obvious of course, but it was not until a geologist named J. Harlan Bretz studied the area in detail in the early 20th century that the story was uncovered. Initially, Bretz’s interpretation was rejected by the “titans” of the science of the time. Sounds familiar doesn’t it? Eventually one of the more powerful geologists of the day, Thomas Crowder Chamberlin, visited the scablands and came around to Bretz’s point of view. It helped that the source lake, glacial Lake Missoula (which Bretz originally did not identify) was identified from ancient shorelines in Montana.
IF YOU VISIT
Over the whole length of the floods, across 4 states, there is abundant evidence that any visitor to the region can see. In recent times the area has been receiving more attention of the tourist variety, but it is still very lightly traveled. There is a great non-profit, called the Ice Age Floods Institute, who pushed congress to establish the Ice Age Floods National Geologic Trail in 2009. The Institute runs great field trips, so if you’re planning to visit this region check out their website in the link above. Most field trips run in spring and summer.
I visited a small portion of the scablands. Traveling west from the Palouse I passed through Othello, visited the Drumheller Channels, and moved on to the Columbia River near Quincy. The Potholes lies between these two. With spring’s high water, I found superb wetlands and wildlife (especially birds) all through this area. But Drumheller Channels was perhaps my favorite, because of its manageable scale and beautiful terrain. It is part of the Columbia National Wildlife Refuge.
- Coulees. The most obvious terrain feature through the scablands is the coulee. The word comes from the French (to flow) and describes any drainage that is intermittently dry and wet. In the Channeled Scablands the coulees take on a variety of sizes, and were all carved by the Missoula Floods. Because the bedrock here is all Columbia River Basalt (a very hard lava rock formed 17 million years ago), the coulees are typically steep-sided. Grand Coulee (site of the large dam), Frenchman’s Coulee, and Moses Coulee are among the largest.
- Giant Ripples. Amazing features that are much rarer than coulees but also testify to the catastrophe are giant current ripples. When you walk along a tidal flat or beach area, you often encounter those small ridges in the mud or sand. They are only an inch or two high. Giant current ripples were formed in a like manner (water currents) but on a huge scale. They can reach 20 meters (66 feet) high! They occur near the town of Quincy on the west bank of the Columbia River, across from the resort of Crescent Bar (see image).
Potholes & Erratics. Another type of flood feature to look out for are the abundant pothole lakes and ponds. These depression, now havens for migrating birds and other wildlife, were either scoured out by the floods or formed when giant icebergs (torn from the ice dam and floated down by the floodwaters) grounded and then melted, leaving a depression. Large rocks carried within these icebergs, rocks like granite that occur in the Rockies but nowhere near this area, were simply dropped on the landscape when the floods receded. Now they stick out like a sore thumb, in fields and along gentle hillsides. They are called glacial erratics. You’ll see them along the Frenchman Hills road just west of Potholes Reservoir, among other places.
- Steptoes. Underlying part of the Palouse is terrain similar to the Scablands. The floods formed three main channels, and the eastern-most carved into the Palouse, eroding away much of the rich soil. Fortunately for us, the floods were no bigger than they were. Otherwise all of the rich loess soils of the Palouse would have been carried away. Underlying all of this are the lava floods of the Columbia River Basalts, one of the world’s great lava provinces. But poking up in a few places (particularly in the Palouse) are small islands of older rock.
Both Kamiak and Steptoe Buttes in the Palouse are made of seafloor sedimentary rock that is much older than the surrounding sea of basalt. A bit of geo-trivia: a steptoe is the name that geologists use for this formation, where older rock pokes up island-like through younger rocks. The name comes from the town and butte of the same name in eastern Washington’s Palouse. Palouse Falls, described in a previous post, is a great place to get a feel for the power and scale of the floods.
I know I will return to the Channeled Scablands for further exploration, and you should do the same if you’re ever passing through the area. If you’re interested in any of these images simply click on them to go to the high-resolution versions. Then click “add this image to cart” to get price information (it will not be added to your cart until you make a choice). Being copyrighted, the images are not available for free download, sorry. Please contact me with any questions. Thanks for reading.