Discover the power of water on the Ice Age floodpath

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The Palouse Falls area exemplifies the ethereal land carvings made by the Ice Age floods. Photo by Keith Yahl. 

Sept. 5, 2018

Are you a geology nerd? Do you geek out on natural history? Do you like to learn while on vacation?

If you answered yes, why not treat yourself to a state parks getaway with an Ice Age floods theme and a chance of sunshine?

Ice Age Floods 101

If you’ve never heard of the Ice Age floods, here’s a primer: during the last ice age, a massive lobe of ice blocked the Clark Fork River near the present-day Idaho-Montana border. This was called glacial Lake Missoula. The ice dam failed many times, releasing cataclysmic floods toward the Pacific Ocean.

These thundering torrents raced southwest into present-day eastern Washington, stripping tons of soil and rock and carving a region known as the Channeled Scablands.      

All that water had to pass through Wallula Gap, where the Columbia River turns toward the Pacific. Floodwaters backed up behind the bottleneck, submerging areas of the Walla Walla, Pasco and Yakima valleys to depths of more than 800 feet!

Eventually, each flood forced its way through the Columbia River Gorge and Willamette Valley before reaching the Pacific Ocean.

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A visitor marvels at the expansive Dry Falls from a viewpoint outside the visitor center. The 3.5-mile wide cliff on the far side of Sun Lakes was a waterfall more powerful than Niagara Falls at times during the floods.


Travel the Ice Age floodpath

If your curiosity is piqued, bust out your maps and smartphones, and follow the Ice Age Floods National Geologic Trail. This multi-state program of the National Park Service includes several Washington state parks. You can explore a few parks in a weekend, or take a cross-Washington road trip.


Go with the flow! Take a tour through Washington's geological history at these parks on the sweeping path of the Ice Age Floods. 


Begin your trip in Spokane, where Riverside State Park’s Bowl and Pitcher offers a look at the floods’ handiwork. Imagine the waters looming several hundred feet higher and running even faster than they do today!

Next, drive an hour north to Mount Spokane State Park and lace up your boots or snowshoes, or drive (in season) to the mile-high summit of Mount Spokane. You’ll be amazed by the views of the inland Northwest, including the location of the ice dam that formed glacial Lake Missoula (occupied today by Lake Pend Oreille).

Grand Coulee area

If you only have a few days, you may want to head for the Grand Coulee and Steamboat Rock State Park. This massive island of basalt was part of a giant Ice Age waterfall. A 650-foot scramble to the rock’s tabletop summit gives you unparalleled views of the upper Grand Coulee.         

Don’t miss Sun Lakes–Dry Falls State Park, 30 minutes south of Steamboat RockThis park contains one of the natural wonders of North America—the Dry Falls cataract. This 3.5-mile-wide chasm of basalt, with a drop of 400 feet, once a powerful waterfall, was left high and dry at the end of the last ice age.

Perched on the cataract rim, the seasonal Dry Falls Visitor Center features educational exhibits, a documentary film and interpretive staff who enjoy chatting about the floods. Visitors can learn about the National Ice Age Flood Geological Trail and get national park passports stamped.

Looking for an afternoon side trip? An hour from Sun Lakes, Ginkgo Petrified Forest State Park is one of the most diverse fossil forests in North America. Famous for the rare specimens of petrified Ginkgo tree discovered there in the early 1930s, this park overlooks the flood-hewn walls of the Columbia River Gorge.

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Hikers will find unique landscapes in the Grand Coulee area, including the Umatilla Rock hike at Sun Lakes – Dry Falls State Park. 

Southeastern Washington

If you can tear yourself away from the swimming, fishing, boating and hiking at Sun Lakes and Steamboat Rock, hop back on the flood path, heading southeast to Washington’s state waterfall at Palouse Falls State Park. Here, the Palouse River pushes through a narrow cataract and drops 200 feet to a churning plunge pool. A winding gorge of basalt cut by the floods brings the river to its confluence with the Snake River at Lyons Ferry State Park, a great place to cool off, picnic and swim.            

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Against a backdrop of flood-hewn basalt cliffs, a picnicker contemplates an afternoon paddle at Columbia Hills Historical State Park.

Columbia River

Traveling a few hours west from Palouse Falls, you’ll enter the the Columbia River Gorge and some of Washington’s most extraordinary scenery.

Floodwaters raced through this sole channel to the ocean at speeds up to 60 miles per hour. Columbia Hills Historical State Park showcases Horsethief Butte, a popular rock climbing area with towering walls of basalt that survived the floods.

An hour’s drive west from Columbia Hills, you’ll find Beacon Rock State Park. Once an active volcano, Beacon Rock had a cone shape until floodwaters scoured its flanks, leaving only its once-molten core. You can hike to the top of the 848-foot rock on a trail of switchbacks that was engineered 100 years ago.

Eventually, each Ice Age flood reached the mouth of the Columbia River and spread out for hundreds of miles along the Pacific Ocean floor. Cape Disappointment State Park marks the end of the Ice Age Flood National Geologic Trail and the place where the mighty Columbia collides with the Pacific Ocean, demonstrating the power of water.

Learn More

Read up on the Ice Age floods:

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