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For relocation or visitor information contact:
111 W. Main Ave
Ritzville, WA 99169
509-659-1936


Mailing Address:
PO Box 122
Ritzville, WA 99169

Palouse Falls

The Channeled Scablands of Eastern Washington are unique on earth; only on the planet Mars are similar landforms found.

Thirty million to 10 million years ago, numerous lava eruptions poured out from fissures, miles in length, onto the Eastern Washington landscape. Some of these flows were small, while others traveled more than 100 miles with depths up to 75 feet. This lava hardened into basalt rock, which measured to a depth of over 10,000 feet in some areas.

After the last eruption, the Eastern Washington area tilted as a unit to the southwest. The basal field was deformed in some areas into ridges, including the Horse Heaven Hills, Rattlesnake Mountains and Saddle Mountain.

The next major geologic event in the northwest was the uplifting of the Cascade Mountains. Erosion washed sand and silt down the east side of the new mountain range where it dried and then blew eastward, deposited on the basalt fields. By the end of this period, this windblown soil - or loess - covered much of Southeast Washington with a frosting of soil.

Near the end of the last Ice Age 20,000 years ago, an ice lobe dammed the mouth of the Clark Fork River in Northern Idaho. Water rose behind this dam and extended into Montana, forming Glacial Lake Missoula, which covered 3,000 square miles at a depth of 2,000 feet with an estimated volume of half of present-day Lake Michigan. When the lake reached the height of the ice dam, water began to breach it. It is estimated that within two days the dam completely failed, releasing a flood of water toward present-day Spokane. It is also estimated that the lake was drained in less than three days and the discharge was 10 times the current flow of all the rivers of the world.

The catastrophic floodwaters quickly reached the Spokane Valley. From there to present-day Grand Coulee Dam the water overflowed the river valley onto the upper edge of the tilted basalt field. The floods followed the natural slope to the Pasco Basin, through Wallula Gap and onto the Pacific Ocean via the Columbia River valley. While overflowing the basalt field, the waters easily eroded the loess soil and cut canyons into the underlying fractured basalt. Soils deposited in the Pasco Basin and Walla Walla valley were blown again northwesterly to form the Palouse Hills.

Recent evidence shows that this sequence happened more than 100 times during the last Ice Age, with the last one occurring less than 13,000 years ago. There is also evidence that similar flooding occurred during earlier Ice Ages.

Adams County's landscape is littered with huge boulders 'dropped' here and there by the floods. The great floods of the Ice Age drastically changed the course of the Palouse River, originally, it flowed through present-day Hooper, Washtucna, Kahlotus and Connell to enter the Columbia River near Pasco.

Floodwaters that spilled onto the plateau in the Spokane area traveled southwest through present-day Cheney and Sprague. Much of this entered the Palouse River Valley at Winona, through the Cow Creek Valley and the Staircase Rapids north of Washtucna.

There was more water than the Palouse Valley could hold and flooding occurred over the divide between the valley and the Snake River Valley southeast of Washtucna. One hundred square miles of loess soil, up to 200 feet thick, washed away. The underlying basalt rock, which had fractured during cooling, eroded easily along these fracture zones to form numerous canyons. The most notable canyon cut across the divide and eventually during one of the floods, the Palouse River took the new route - The Palouse Canyon - across the divide and entered the Snake River at Lyons Ferry. The lower part of the Palouse Valley is now the Washtucna Coulee. (A coulee is an abandoned river valley.) At this location during the height of the flood, you would be standing under more than 200 feet of water.

Palouse Falls drops 196 feet and is located in the middle of the Palouse Canyon. Palouse Falls State Park provides excellent views of the falls and the canyon.

Read more about The Channeled Scablands of Eastern Washington at the United States Geographical Survey website.

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