The Largest Waterfall That Ever Existed – BBC

8 June 2017

A state of two worlds

The Cascade Mountains in the US state of Washington split the state into two wildly different climate zones. In the west, thick, mossy forests and snowcapped mountains extend from Canada to Oregon; this is where you’ll find Seattle and all three of Washington’s national parks. But east of the mountains is a land that many people don’t know, dominated by a massive, semi-desert environment of grassland and rocky formations called the Channeled Scablands. (Credit: Zack Frank)

Ancient Floods

Around 15,000 years ago, an enormous glacial dam held back a body of water known as Lake Missoula, which contained roughly half the volume of present-day Lake Michigan. As the ice age came to an end, the ice dam broke, releasing water that carved a 660ft deep, 60-mile-long canyon into solid basalt, one of the hardest forms of rock. The resulting earthen gash and the brown, rocky cliffs that remained at the canyon’s edge gave the Scablands their name. (Credit: Zack Frank)

A natural wonder

The Missoula Floods, the name given to the deluge released from Lake Missoula after the ice dam collapsed, are responsible for the most recent major shift in the geological structure of the United States; signs of the water’s influence can be seen as far away as Portland, more than 200 miles south-west. (Credit: Zack Frank)

Breaking records

Dry Falls (pictured), the site of a former waterfall, is a horseshoe-shaped cliff that’s twice as high and three times as wide as Niagara Falls, making it the largest confirmed waterfall in the planet’s history. Today, the site is preserved as Sun Lakes-Dry Falls State Park, where visitors can see the impact of these relatively recent geologic events through overlooks, canyon trails and interpretative displays. (Credit: Zack Frank)