Echoes of the Ice Age: The Dramatic Formation of the Channeled Scablands by Ancient Floods

by Mateo Gonzalez
6 comments
Channeled Scablands

This section of the scablands was photographed from space by Landsat 8’s Operational Land Imager on May 14, 2023.

The Channeled Scablands in Washington state were shaped by massive floods from Glacial Lake Missoula.

In the southeastern part of Washington state, extensive farmlands form neat patterns over undulating hills, growing a variety of crops on the fertile land of the Columbia Plateau. However, some areas are marked by winding trails of eroded earth, disrupting the neat farmland patterns and irrigated circles.

These distinct geological formations, known as the Channeled Scablands, were created by catastrophic flooding events between 10,000 and 20,000 years ago. The image from Landsat 8’s OLI shows a segment of these scablands, located approximately 120 kilometers (75 miles) west of Spokane, captured on May 14, 2023.

For years, the origins of the unique formations puzzled geologists. It was later understood that during the last ice age, the southward-moving Cordilleran ice sheet formed a natural ice barrier along the Clark Fork River. This barrier led to the creation of Glacial Lake Missoula in present-day western Montana, which at its peak held as much water as Lakes Erie and Ontario combined. It’s believed that this ice dam broke and reformed multiple times over thousands of years, each time releasing around 600 cubic miles of water, dramatically reshaping the landscape.

Close-up from the aforementioned image.

The floodwaters traveled south and southwest, eventually merging with the Columbia River. They sculpted grooves, basins, and long channels known as “coulees” into the volcanic basalt foundation. The close-up image displays one of these channels, highlighting the stark difference between the eroded land and the surrounding agricultural areas.

The canyons seen here are small in comparison to the Grand Coulee, the most extensive in the Channeled Scablands, located north of this area. The Grand Coulee Dam, completed in 1942, was once the world’s largest concrete structure until it was overtaken by the Itaipú Dam in South America in 1984 and the Three Gorges Dam in China in 2006. Today, it stands as the largest hydropower facility in the United States and supplies irrigation to the Columbia Plateau.

Images courtesy of NASA Earth Observatory, captured by Lauren Dauphin, utilizing data from the U.S. Geological Survey.

Frequently Asked Questions (FAQs) about Channeled Scablands

What are the Channeled Scablands in Washington State?

The Channeled Scablands are a unique geological area in southeastern Washington, characterized by deep grooves and canyons formed by catastrophic flooding events 10,000 to 20,000 years ago. These events were caused by repeated ruptures of an ice dam at Glacial Lake Missoula, resulting in massive water flows that sculpted the landscape.

How were the Channeled Scablands formed?

The Channeled Scablands were formed by the massive and repeated outbursts of water from Glacial Lake Missoula when the Cordilleran ice sheet, moving southward during the last ice age, created a natural ice dam. This dam broke and reformed multiple times, releasing vast amounts of water that carved out the scablands.

What does the Landsat 8 image from May 14, 2023, show about the Channeled Scablands?

The Landsat 8 image taken on May 14, 2023, provides a detailed view of a portion of the Channeled Scablands. It highlights the contrast between the rugged, flood-sculpted terrain and the surrounding agricultural land, showcasing the area’s distinct geological features.

What is the significance of the Grand Coulee in the Channeled Scablands?

The Grand Coulee is the largest canyon within the Channeled Scablands, north of the photographed area. It’s significant not only for its size but also because the Grand Coulee Dam, completed in 1942, was the largest concrete structure at the time. It is now the largest hydropower facility in the U.S. and plays a key role in irrigating the Columbia Plateau.

More about Channeled Scablands

  • Channeled Scablands Geology
  • Formation of Glacial Lake Missoula
  • Landsat 8 Satellite Imagery
  • Grand Coulee Dam History
  • Ice Age Floods and Geology
  • NASA Earth Observatory Resources
  • U.S. Geological Survey Data
  • Columbia Plateau Agriculture
  • Volcanic Basalt in Washington State Geology
  • Historical Structures of Hydropower Facilities

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6 comments

Linda S December 26, 2023 - 5:35 am

the history of these places is always fascintating to me, how much we can learn from just looking at the earth.

Reply
Dave W. December 26, 2023 - 10:57 am

the photo from landsat 8 looks incredible, wish they showed more pics like these in school

Reply
Mike Johnson December 26, 2023 - 3:46 pm

really cool how these scablands got formed.. nature is amazing huh??

Reply
Sarah K December 26, 2023 - 4:59 pm

i didn’t know about the grand coulee dam being so big. its interesting to learn new stuff like this.

Reply
Kevin R. December 26, 2023 - 8:48 pm

so this lake missoula was like HUGE! hard to imagine so much water just rushing out like that, must’ve been crazy

Reply
Emma Thompson December 27, 2023 - 12:46 am

always thought geology was kinda boring but this article makes it sound pretty interesting actually!

Reply

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