Associated Press

MOXEE — A cataclysmic flood that broke through an ice dam in western Montana 12,000 years ago to carve out the Columbia Plateau may have deposited a mammoth relic in Moxee.

The ice age floods were so powerful they carried granite boulders the size of houses from the Rocky Mountains to as far away as Eugene, Ore.

On May 10, Steve Herke was grading a new parking lot in this little town just east of Yakima when he uncovered a fossilized mammoth tusk about 4 1/2feet long.

"We knew it was something special," Herke said Wednesday.

The dirt parking lot is one of 40 such mammoth sites in the state.

The Yakima Valley Museum will excavate the tusk, and it will become part of an exhibition on the region’s prehistoric past, said Andy Granitto, museum curator.

The site around the parking lot, which Herke was grading for Alexandria Moulding Inc., has been fenced off and the tusk covered to protect it from the weather.

Fossil experts from Central Washington University, Yakima Valley Community College and the National Parks Service believe the tusk came from a Columbian mammoth from the Pleistocene era, which began about 1.8 million years ago and ended about 11,000 years ago.

During the excavation this summer, researchers will dig through 16 feet of soil to an ancient riverbed and study the stratified layers of dirt and rocks to learn more about the site.

The tusk was initially deposited about 8 feet above the riverbed.

Researchers will tunnel to the fragile piece and build a case around it before moving it to the museum for study.

Exposure to dry air has already caused the top layers to fracture.

"It’s almost dried into a powder," said Dan Close, general manager at Alexandria Moulding.

Last year, pieces of ivory tusk were unearthed at a construction site at Lakeview Elementary School in Kirkland. That tusk was initially believed to be from a mastodon, in part because mastodon remnants are more common in the Puget Sound area, though both shaggy, elephantlike and long-extinct mammals ranged throughout the region. Lab tests showed the tusk came from a mammoth.

Both mammoths and mastodons lived in North America during the ice age, but mammoths appeared first. They preferred open areas and a diet of grasses, while mastodons were leaf-eating, forest-dwelling creatures.

Tusks and teeth from a mastodon were found in 1958 in Granger, a lower Yakima Valley town about 20 miles south of Moxee.

Mammoths are believed to have stood about 14 feet tall at the shoulder and weighed up to 8 tons.

Researchers around the world continue to try to determine what killed off mammoths and other prehistoric animals. Theories range from changes in climate to hunting by humans to infection and disease.

On the Net: http://yakimavalleymuseum.org

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