Discovered through megafloods, this location eluded scientists for several decades

In the heart of eastern Washington, a desert region that receives less than eight inches of rain annually, lies a testament to one of Earth's most remarkable geological events - the Channeled Scablands. This terrain, a labyrinth of braided waterways, was sculpted by a series of colossal floods during the last ice age.

The catalyst for these floods was Glacial Lake Missoula, a giant ice-age lake that formed when the Cordilleran ice sheet progressed south and blocked the Clark Fork river valley, creating an ice dam 2,000 feet high. Behind this dam, water from the Clark Fork gathered, amassing more water than Lakes Erie and Ontario combined, stretching for hundreds of miles in Montana's mountainous river valleys.

The breaking of this ice dam unleashed a torrent of water with ten times the combined flow of all the world's rivers. This flood, reaching speeds approaching 80 miles per hour, repeatedly scoured the landscape, carving canyons, cutting waterfalls, and shaping the unique topography of the Channeled Scablands.

The first hints of these floods were discovered by Joseph Pardee, a geologist for the USGS, in the early 1940s. Later, in 1909, Harley Bretz, a high school science teacher, noticed a striking feature on a topographic map of the Quincy Basin: a huge cataract called Potholes Coulee, with no apparent source of water. Bretz's research suggested that a massive flood, perhaps the largest in Earth's history, could have caused this landscape, including Dry Falls - once the largest waterfall in the world, now completely dry.

Subsequent research indicates that over 80 floods ravaged the scablands near the end of the last ice age. Richard Waitt, a geologist with the USGS, found evidence of at least 40 ice-age floods in the scablands, arguing that each of the sediment layers represented a separate flood event.

The floodwaters from Glacial Lake Missoula converged into the Columbia River Gorge and eventually emptied into the Pacific. The area around Dry Falls, known as the Columbia Plateau, has hundreds of other dry waterfalls, canyons without rivers, mounds of gravel as tall as skyscrapers, deep holes in the bedrock, and countless oddly placed boulders.

Bretz's hypothesis was controversial and met with criticism from geological experts, who believed that geological change was gradual and uniform. However, Bretz's work has since been vindicated, and the Channeled Scablands stand as a testament to the power and scale of these massive ice age floods.

Discovered through megafloods, this location eluded scientists for several decades