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Washington Nature Weekends

Ice Age Floods National Geologic Region Heritage Trail

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Ice Age Floods Resources:

Proposed Ice Age Floods Trail
Proposed Ice Age Floods Trail (Excerpt from the above link)

"There are seven National Natural Landmarks (NNLs) located within the Ice Age Floods region. A National Natural Landmark is a nationally significant area that has been designated by the Secretary of the Interior.  To be nationally significant, a site must be one of the best examples of a type of biotic community or geologic feature in its physiographic province. 

The floods-related NNLs (in Washington) are:

  • Wallula Gap, Washington—Glacial outburst waters that crossed the Channeled Scablands during the Spokane floods were channeled through Wallula Gap. For several weeks, as much as 200 cubic miles of  water per day was delivered to a gap that could discharge less than 50 cubic miles per day. Ponded water filled the Pasco Basin and Yakima and Touchet valleys to form temporary Lake Lewis.
  • The Great Gravel Bar of Moses Coulee, Washington—This bar is perhaps the largest example of bars created by outburst floods on the Channeled Scabland. The bars are well-preserved and have only sparse vegetation.
  • Drumheller Channels, Washington—The site is a spectacular tract of butte-and-basin scabland and provides excellent geomorphic evidence for late Pleistocene catastrophic floods on the Columbia Plateau.
  • Grand Coulee, Washington—Grand Coulee is the largest coulee in the Columbia Plateau and is probably the world’s finest example of a recessional cataract gorge." 



Identifying Ice Age Floods Resources in Montana
(Excerpt from the above link)

"In Montana the Pathways follow I-90 west from Goldcreek to Missoula on the Goldcreek Spur. The Bitterroot spur runs north from Hamilton via U.S. Highway 93 to Missoula. The Potomac Valley Spur leads from Missoula to Milltown and north on State Route 200 and north on State Route 83 to Salmon Lake. Along these spurs are Floods features that are well-exposed, including wave-cut shorelines on the mountains bordering Missoula.

The Floods Pathways route begins in Missoula and proceeds west on I-90 to State Route 93/200 and north to Ravalli, west on State Route 200 to Route 382 and north Camas Prairie and south on State Route 28 to Plains and west on State Route 200 to the Idaho state line.
 

Ice Age Floods Map
Tour Route in the Gorge, Lower Columbia and Willamette Study Zone

The Flathead Lake Loop proceeds from Ravalli on U.S. Highway 93 to Polson and east and north on State Route 35 to State Route 82 near Big Fork. The loop continues west to Somers and south on U.S. Highway 93 to Polson. The Camas Prairie Loop continues south on State Route 28 at Elmo, past Camas and Hot Sprints to Plains, east on State Route 200 to Perma and north on Route 382. The St. Regis Loop begins at Missoula and progresses west on I-90 to St. Regis, north on State Route 135 to State Route 200 and east to Ravalli and south to I-90 and Missoula. The Camas Prairie Loop passes south of Camas. The giant ripples on Camas Prairie were formed by the fast-moving bottom waters of Glacial Lake Missoula during its draining.

Along these spurs, features evidencing Glacial Lake Missoula are well-exposed, including wave-cut shorelines at Missoula and giant ripples at Camas Prairie formed by fast-moving bottom waters of the lake during its draining."



Identifying Ice Age Floods Resources in Idaho
(Excerpt from the above link)

As the ice dam repeatedly failed, flood waters from numerous Glacial Lake Missoulas crashed into the landscape of northern Idaho. The Pathways continue along State Route 200, which is under study as a Scenic Byway by Idaho DOT, to the northern edge of Lake Pend Oreille and Sandpoint. Here the waters flooded west toward Priest River on U.S. Highway 2, southwest along the Purcell Trench on U.S. Highway 95, and mostly south through Lake Pend Oreille and over Farragut State Park. At Rathdrum Prairie, east of Spirit Lake, the Floods created giant ripple marks and left gravel bars and sediments as a record of the Floods passage. The Rathdrum Prairie Loop on State Routes 54 and 53 takes visitors to Post Falls, where the flood waters may have reached speeds of 50 to 60 miles per hour. I-90 from Coeur d’Alene to the Washington State border provides views of landscapes impacted by the Floods.

 

Ice Age Floods Map
Tour Route in the Gorge, Lower Columbia and Willamette Study Zone



Identifying Ice Age Floods Resources in Washington State
(Excerpt from the above link)

Floodwaters rushing into Washington flowed down the Spokane River Valley along the current route of I-90. The Mt. Spokane Loop from Priest River and Newport passes Mt. Spokane State Park, which offers superb views back into Idaho and the Spokane Valley. Near Spokane, the waters split, with one arm following the Spokane River to its junction with the Columbia River. The other spills over into the Cheney-Palouse drainage. The Cheney-Palouse can be seen from U.S. Highway 95, which parallels Hangman Creek. The Turnbull National Wildlife Refuge, near Cheney, contains significant Floods features. 

The Cheney-Palouse Scablands Loop follows U.S. Highway 195, county roads to Rosalia and Malden, and State Highway 23 at St. John, then northwest I-90 at Sprague. Here visitors return to Spokane via I-90 or continue northwest to Harrington on State Route 23 and then north to Davenport. U.S. Highway 2, which goes through Davenport from Spokane, defines the Medical Lake Loop.  Columbia Plateau Trail State Park also provides opportunities for the public to review Floods features. 

The Telford Loop, off U.S. Highway 2, follows State Route 28 to Odessa and then north on State Route 21 to Wilbur. This Loop and the Channeled Scablands Loop goes through the heart of the Channeled Scablands, which is dotted with many lakes and scour channels. The Channeled Scablands Loop includes the area generally south of Odessa and contains a maze of flood-related coulees such as Lind, Washtucna and Weber Coulees. State Routes 260, 26 and 21 provide access to much of this area. Each road in the area leads the visitor to another Floods channel or scour area.

Ice Age Floods Map
Tour Route in the Mid Columbia Study Zone

To the north of U.S. Highway 2 at Davenport, the Hawk Creek Loop takes visitors to the Columbia River and the mouth of the Spokane River and then back to U.S. Highway 21 east of eston. Here the Pathways continue along U.S. Highway 2 to Wilbur and State Route 174, which leads to Grand Coulee, Grand Coulee Dam and the Columbia River. The roaring floodwaters enlarged Grand Coulee as they headed southwest to Dry Falls, poured over the eastern coulee wall, and created a maze of channels, buttes and dry cataracts.  State Highway 155, built on the floor of the Grand Coulee, is a spectacular drive leading to Coulee City and nearby Dry Falls.

Dry Falls, located on State Route 17, is part of the Sun Lakes / Dry Falls State Park. It is a premier site because of existing facilities and the fact that it is the scene of a major cataract. The section of State Route 17 from Dry Falls to Soap Lake follows the course of the lower Grand Coulee. 

Closely related to Dry Falls is the area included in the Upper Crab Creek Loop. Immediately west of the Telford Loop, the Upper Crab Creek Loop includes Wilson Creek, which is located on State Route 28 from Soap Lake to Odessa. Wilson Creek was one of the areas originally studied by Bretz. Other significant Floods resources are located within the Upper Crab Creek Loop. 

To the west of State Route 17 is a complex of three Loop Pathways: Waterville Plateau, Wenatchee, and Moses Coulee Loops. The Waterville Plateau Loop on U.S. Highway 2 west of Coulee City includes the area that would have been the southern terminus of the ice sheet. It contains some gigantic erratics adjacent to the highway. U.S. Highway 2 continues along the Columbia River above Wenatchee where U.S. Highway 97 follows along the east bank of the Columbia to East Wenatchee and into the Moses Coulee Loop. Moses Coulee was carved by the Floods. 

Continuing east on State Route 28 brings the visitor to Quincy Basin, a remnant of Lake Lewis, and to the Quincy Basin Loop. For visitors wishing to proceed west, State Route 283 intersects with I-90 at George and proceeds past Frenchman Coulee to the Columbia River, Vantage, and Ellensburg. Visitors could continue on State Route 243 to the Drumheller Channels  Loop. Along the Lower Crab Creek in the Columbia National Wildlife Refuge lies a marvelous collection of butte and basin Floods remnants. After viewing this area, visitors could proceed north to Moses Lake and I-90, or go south on State Route 17.

Continuing south on State Route 17 to State Route 260, visitors encounter two Loop Pathways, the Walla Walla Basin and Palouse Falls Loop. The two can be combined into one rather large loop that leads to Lewiston, Idaho, and back along U.S. Highway 12 past Walla Walla. Just off U.S. Highway 12 on State Route 261 is Palouse Falls State Park, a dramatic Ice Age Floods creation. 

All the roads into the general areas lead to the Tri-Cities, which lie near the confluence of the Snake, Columbia, and Yakima Rivers. The Yakima Valley Loop goes from Ellensburg on I-82 and leads past Yakima where State Route 24 leads to the western edge of the Lower Crab Creek Loop. The Tri-Cities Loop follows U.S. Highway 730 to Wallula Gap, a narrow constriction of the Columbia River that caused the waters to temporarily back up and create Lake Lewis. In basins created by Lake Lewis are excellent examples of rhythmites and other depositions, as well as erosional features related to the Floods."
 



Identifying Ice Age Floods Resources in Oregon (and WA)
(Excerpt from the above link)

Beyond Wallula Gap, Floods waters inundated the Umatilla and Dalles Basins, creating Lake Condon. Along this part of the Columbia River, two highways parallel the river, I-84 on the south bank and Washington’s State Route 14 on the north bank. Together, these two routes form the Columbia River Loop. The Pendleton Spur of I-84 leads to the Columbia River at Umatilla. Between here and The Dalles, State Route 14 provides visitors outstanding views of the river and the effects of the Floods. Visitors could cross onto I-84 and the Historic Columbia River Highway to Crown Point.  Crown Point is 700 feet above the river level and was topped by floodwaters during the Ice Age Floods. State Highway 14 and I-84 form the Gorge Loop, which runs from The Dalles to Portland. 

Ice Age Floods Map
Tour Route in the Gorge, Lower Columbia and Willamette Study Zone

North of Portland on I-5, the Pathways continue to the Kelso/Longview area. The Castle Rock Spur connects Castle Rock and the Kelso/Longview area. The Pathway turns west on Washington State Route 4 on the north bank of the Columbia to Megler near the meeting of the Columbia River and the Pacific Ocean. U.S. Highway 30 leads from Portland to Astoria along the south bank of the Columbia River, forming the Lower Columbia Loop." 

Oregon

Just to the west of Crown Point is the Portland-Vancouver Basin. A hydraulic dam at Kalama Gap forced flood waters to back up into the Willamette Valley and swirl around the landscape near Portland. Interstates I-84, I-205, and I-5, U.S. Highways 26 and 30, and State Route 99-W and 99-E all lead to Floods resources in the Portland area. The Hillsboro Loop leaves Portland on U.S. Highway 26 to State Route 47 and south to State Route 99-W. Following State Routes 213 and 214 will lead visitors to the Mt. Angel Loop. The Big Bend Loop leads visitors southwest of Portland on 99-W to State Route 22 west of Salem. South of Portland, I-5 and State Routes 99-W, 99-E. 18, 22, 34, 228, and 126 lead to Flood resources in the Willamette Valley as far south as Eugene. The Willamette Valley spur runs from Salem to Eugene.


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Links checked and updated on:  September 1, 2003
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