Drive north from the little town of Moses Lake in Eastern Washington, along the often lonely Highway 17, and you'll start to notice boulders...

Drive north from the little town of Moses Lake in Eastern Washington, along the often lonely Highway 17, and you’ll start to notice boulders the size of beach balls littering the fields along the road.

Keep heading north and the boulders get bigger, turning into rounded, weathered hunks of rock the size of Volkswagen Beetles. The boulders are remnants of a series of catastrophic floods that carved and shaped the unique landscape known as the Channeled Scablands.

The scablands cover much of Eastern Washington from the edge of the Palouse region to the Columbia River.

They were formed when vast ice-age lakes spilled over and burst ice dams created by glaciers, and torrential waters rolled across the landscape at up to 80 mph. The force and speed of the water flowed into the bowl-like Columbia Basin and carved canyons, cataracts, giant ripples and potholes.

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This happened hundreds or possibly 1,000 times starting 1 million or 2 million years ago and was repeated during cooling cycles until the last ice-age 13,000 years ago, said Bruce Bjornstad, a geologist and author of “On the Trail of the Ice Age Floods: A Geological Field Guide to the Mid-Columbia Basin.”

One of the most impressive features left behind by the floods is Dry Falls, a 400-foot-high, 3-mile-wide cataract where floodwaters once spilled over the greatest waterfall in the world. (It lies within Sun Lakes State Park.)

Another is Palouse Falls, where the Palouse River was diverted from its former path toward Pasco over a cataract and eventually into the Snake River at Lyons Ferry. (It’s within Palouse Falls State Park.)

Stand at the edge of Dry Falls, along Highway 17 about 18 miles north of Soap Lake, and you get a sense of the vastness and ancientness of the landscape.

No water now tumbles over the falls, but Dry Falls once roared mightier than Niagara Falls, which is less than one-third as wide and half as high.

Fences around part of the rim of Dry Falls allow visitors to stand and gaze in awe at its magnitude and the remnants of plunge pools below.

A small interpretive center tells the story of the ice-age floods and includes a gift shop with trinkets and books about the area’s geology, wildlife and Native American past. Admission is free.

Palouse Falls State Park doesn’t include an interpretive center, but it does offer spectacular views of the spot where the river plunges 200 feet.

A quarter-mile hiking trail leads to an observation point along the cataract’s rim.

Today’s residents have reaped numerous benefits from the ice-age floods, which carved channels now used for irrigating farmland and deposited the rich, fertile soils that have made the region famous for its wineries and other crops.