Is the Colorado Plateau still rising?

Is the Colorado Plateau Still Rising? (A Human’s Take)

The Colorado Plateau. Just the name conjures up images of vast canyons, towering mesas, and landscapes that seem to stretch on forever. This incredible region, spread across parts of Colorado, Utah, Arizona, and New Mexico, has had geologists scratching their heads for ages. Unlike the crumpled and folded terrain around it, the Plateau remains surprisingly intact. But here’s the million-dollar question: is this ancient landscape still on the rise?

A Slow Climb Through Time

The Plateau’s story is a long one, a real slow burn of geological activity. Think of it as a series of elevator rides, rather than one sudden jump. It all started around 70 to 50 million years ago, during a mountain-building event called the Laramide Orogeny. Back then, this whole area was pretty much at sea level – hard to believe, right? You see, marine sediments found way up high tell that story. Then, things got interesting. There were more uplifts around 38-23 million years ago, and again less than 20 million years ago. These bumps were likely caused by molten rock bubbling up from below and some tectonic shenanigans. And then, BAM! About 5 million years ago, the whole shebang – the Rockies and the Plateau – shot up another 4,000 to 6,000 feet! That’s how it got to its current lofty perch, averaging around 6,500 feet above sea level.

Signs Pointing Upwards?

So, is the Plateau still inching its way skyward? Well, there are clues that suggest it might be.

• The Grand Canyon’s Story: First, there’s the Grand Canyon. That massive gash in the Earth didn’t just appear overnight. The Colorado River carved it over millions of years, and the speed at which it happened suggests the Plateau was rising as the river worked its magic. It’s like the river was trying to keep up with the rising land!
• Deep Earth Rumblings: Then, there’s what’s going on deep beneath the surface. Imagine a cosmic lava lamp. Hot rock from the Earth’s mantle is rising up, pushing against the Plateau from below. This upwelling can cause the rocks to expand and become buoyant, lifting the plateau.
• Little Cracks and Tilts: Sure, the Plateau is pretty stable, but it’s not completely still. There’s some faulting and tilting going on, especially around the edges. It’s like the Plateau is settling in its seat, with a few minor adjustments here and there.
• Rock-Solid Evidence: Scientists who study the thermal history of rocks (yes, that’s a thing!) have found that the Plateau hasn’t eroded much in the last 30 million years. This suggests that uplift has been happening, keeping pace with erosion.

What’s Pushing It Up?

The million-dollar question, of course, is why is the Plateau rising (if it is)? There are a few ideas floating around.

• Mantle Plume Power: Maybe there’s a giant plume of hot rock pushing up from deep within the Earth. Think of it like a giant hot air balloon inflating beneath the Plateau.
• Thinning Skin: Subduction, where one tectonic plate slides under another, might have thinned out the Earth’s crust under the Plateau, making it lighter and more buoyant.
• Asthenosphere Invasion: The asthenosphere, a partially molten layer beneath the Earth’s crust, could be nibbling away at the underside of the Plateau. As this molten rock cools and solidifies, it expands and lifts the Plateau.
• The See-Saw Effect: When erosion removes material from the surface, it lightens the load on the crust. This can cause the crust to bounce back up, like a see-saw when someone gets off.

A Work in Progress

The Colorado Plateau is a work in progress, a landscape shaped by the constant push and pull of uplift and erosion. While we know it’s been rising for millions of years, the question of whether it’s still rising is a complex one. The evidence suggests it might be, but more research is needed to nail down the details. One thing’s for sure: this incredible region will continue to fascinate and inspire us for generations to come. And who knows, maybe someday we’ll have a definitive answer to the question of its ongoing rise. Until then, we can just marvel at its beauty and wonder at the forces that have shaped it.