Wenatchee Valley Ice Age Floods Overview
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Driving through central Washington, one can’t help but notice an extraordinary geological panorama unfolding along the roadways. What most people fail to realize is that the entire terrain—hillsides, cliffs, valleys, and canyons—created over millions of years, was dramatically reshaped by an unusual series of events, which took place during the end of the last Ice-Age.

Approximately 17,000 years ago near the end of the Pleistocene Epoch enormous glaciers covered nearly one third of North America. The western portion of the glacial ice was known as the Cordilleran Ice Sheet and the eastern portion as the Laurentide Ice Sheet. East of the Cascade Mountains, the Okanogan lobe of the Cordilleran Ice extended south on a line between what is now Chelan and Coulee City.

Farther east a lobe of advancing ice blocked the Clark Fork River at the point where the river passed through the Bitterroot Mountains. This buildup of ice blocked the drainage of a large portion of what is now northwestern Montana. The subsequent backup of water from the melting glaciers formed an enormous lake known today as Glacial Lake Missoula. Although we don’t know the eventual height reached by the ice dam, high water marks on the mountainside indicate a depth of approximately 2000 feet.

Exactly what happened next is still open to speculation; however, evidence shows the ice dam was eventually breached. When the dam collapsed it permitted catastrophic flooding of the landscape to the west. With incredible force, approximately 500 cubic miles of water and glacial ice burst through the channel gap, sweeping all before it, as it roared westward.

This massive flow of water scoured the soil from the landscape, breaking loose enormous chunks of rock, which it rolled and tumbled along for miles. Iceburgs with incorporated large boulders or “erratics” floated on the muddy turbulent flood-waters until finding a quiet resting place sometimes hundreds of miles from their ice dam origin.

It is believed the force of the rushing water was so great a mere four days were required to drain the entire lake. Today, we can see evidence of how the floods carved out more than 50 cubic miles of earth, deposited mountains of gravel, and scattered 200 ton boulders across the landscape. This astounding process is believed to have happened not once, not twice, but again and again, possibly as many as 100 or more times.

Entering this turbulent scene came an early ice age hunter. One theory being that Ice-Age hunters following big game crossed into the New World via the Bering land bridge. This migration route was open at the peak of the last ice age 20,000 to 15,000 years before the present. It is believed an ice-free corridor between the western Cordilleran and eastern Laurentide Ice Sheets may have developed approximately 15,000 years before the present. Although conditions were extremely hazardous, it is possible animals and hunting groups may have moved southward, traveling through this corridor and into the region.

What is known is that during the installation of an irrigation line in East Wenatchee on May 27, 1987, orchard workers discovered credible evidence of what archaeologists have described as “The First Americans,” a nomadic hunting culture of the Pleistocene Epoch of the New World. The orchard workers discovered a cache of enormous spear points and knives subsequently identified as Clovis points-a designation commemorating the geographic location of the first fluted projectile point site discovered near Clovis, New Mexico. To date, this site—the Richey Clovis Cache in East Wenatchee—has yielded one of the largest fluted stone tools ever found (9.25 inches as compared to earlier discoveries measuring 6 inches). Of even greater significance, the East Wenatchee site contained more artifacts in situ, (undisturbed) within a contained area than any site previously discovered.
During subsequent archaeological excavations, approximately sixty-nine stone and bone artifacts were removed from the shallow pit. The 1990 excavation ended in November of that year; the pits were backfilled, covered with a concrete slab, and once again, the site reverted to orchard.

Wenatchee Valley Museum and Cultural Center, one of the participants in the 1990 excavation, highlights this exciting discovery with an exhibit interpreting the geology of the region, the archaeological discoveries, and a display of materials from the Clovis site. Come, visit the Museum at 127 S Mission Street in Wenatchee. You will enjoy learning more about this exciting archaeological discovery as well as the history of the region.

The image above is an original painting by artist, Stev Ominski. His painting, “Above Wenatchee” depicts the floods waters at approximately 1,700 ft above the water level that exists today. At their highest point the water rose nearly to the top of “Saddlerock” the landmark depicted in the painting.

Additional information about the Ice Age Floods is available at www.iceagefloodsinstitute.org

Contact the WVCVB at 800-572-7753 or marcia@wenatcheevalley.org for information.