What type of volcano is Columbia Plateau?

The Columbia Plateau: Not Your Average Volcano (and Why That’s Awesome)

Forget everything you think you know about volcanoes. The Columbia Plateau, sprawling across Washington, Oregon, and Idaho, isn’t some picturesque, cone-shaped mountain blowing its top. Nope, this is something far more epic: a landscape forged by unimaginable floods of lava. We’re talking about flood basalts, a type of volcanism that went totally wild and reshaped the entire region. Think of it as Mother Nature’s ultimate redecorating project. This makes it a textbook example of a large igneous province, a term that basically means “a whole lotta magma, all at once.”

Flood Basalts: Ditching the Cone for Cracks

So, what exactly are flood basalts? Well, instead of erupting from a single vent like your typical volcano, they ooze out from fissures – giant cracks in the Earth’s crust. Imagine squeezing a tube of toothpaste, but instead of minty freshness, you get rivers of molten rock. Over a (geologically) short period, mind you, massive amounts of basaltic lava just poured out, blanketing everything in sight. These weren’t explosive eruptions, either. More like slow-motion, fiery floods of super-runny lava.

The Columbia River Basalt Group (CRBG) is one of the youngest and best-preserved examples of this kind of volcanic activity on the planet. Back in the Miocene epoch, between 17 and 6 million years ago, a series of eruptions unleashed an estimated 42 trillion gallons of lava. That’s enough to bury the entire state of California under several feet of rock! All that lava covered roughly 63,000 square miles. Some folks even think the volume could be closer to 90,000 cubic miles. The sheer weight of all that basalt actually made the Earth’s crust sink, creating the Columbia Basin. Talk about a heavy pour!

How the Plateau Came to Be

The Columbia Plateau didn’t form overnight. It was a multi-stage process, with the most intense eruptions happening between 17 and 14 million years ago. Get this: over 99% of the basalt erupted during that relatively brief window. And these lava flows? They weren’t continuous. Thousands of years could pass between them. The lava oozed out from countless dikes – think of them as underground plumbing – mainly in southeastern Oregon and northeastern Washington. The Chief Joseph Dike Swarm, near Joseph, Enterprise, and Walla Walla, is estimated to have contained up to 20,000 of these fissures. Can you imagine stumbling across that many cracks in the ground?

The CRBG is further divided into formations like the Steens Basalt, Imnaha Basalt, Grande Ronde Basalt, Wanapum Basalt, and Saddle Mountains Basalt. The Grande Ronde Basalt alone accounts for about 85% of the total lava volume. If you ever get a chance to visit the Columbia River Gorge, you can see firsthand how these flood basalts flowed right through the Cascade Range. It’s a truly awe-inspiring sight.

The Lay of the Land

Today, the Columbia Plateau is known for its vast, flat plains of basalt rock. You’ll often see columnar jointing, those cool, geometric columns that formed as the lava cooled and contracted. Erosion, especially from the cataclysmic Missoula Floods, has carved into the basalt layers, revealing the plateau’s incredibly rich geological history. It’s like a giant, open-air textbook!

The Bigger Picture: Environment and Research

The Columbia River Basalt eruptions weren’t just a geological spectacle; they also had a major impact on the environment. The release of greenhouse gases, like sulfur dioxide, might have cranked up the global thermostat during the mid-Miocene. Interestingly, unlike some other massive volcanic events, the CRBG eruptions didn’t trigger a mass extinction.

Scientists are still hard at work trying to piece together the whole story of the CRBG. They’re studying the timing and pace of the eruptions, figuring out where the magma came from, and assessing the impact on the climate and environment. There’s even research into the connection between the CRBG and the Yellowstone hotspot. It’s a complex puzzle, and geologists are loving every minute of it.

Final Thoughts

The Columbia Plateau is a truly remarkable place, a testament to the raw power of flood basalt volcanism. Its formation involved a series of colossal eruptions that not only reshaped the landscape but also influenced the Earth’s climate. And with ongoing research, we’re constantly learning more about this unique and fascinating geological wonder. So, next time you’re road-tripping through the Pacific Northwest, take a moment to appreciate the sheer scale and drama of the Columbia Plateau. It’s a volcano like no other.