It was windy, and the little boat bounced on whitecaps as it crossed the Columbia River. On May 9, Walla Walla District archeologists and natural resource management staff were heading out to meet with tribal and community members to discuss an important discovery on Corps land.
One of the people in this group was a member of the public who, on April 14, had found something very special while hiking on Corps land: a mastodon jawbone.
The fossil most likely found its way to the beach after tumbling down the side of an eroding bluff. It was then found after the river washed it clean of sediment.
The hiker knew that fossils found on federal lands are federal property. So instead of taking the jawbone, he covered it up and contacted county officials, who contacted the Corps of Engineers.
“He did the right thing. He did not take it; he did not remove it from federal land. That would be theft of government property,” Walla Walla District Archeologist Pei-Lin Yu said. “The law requires that you protect finds and report them.”
The jawbone wasn’t the only fossil the hiker found at the site. He also presented pieces of petrified wood and a scapula (shoulder bone) of an as yet unidentified animal. The group walked the beach to ensure there were no more fossils or cultural items lying exposed. No additional pieces were found, and the discovered fossils were brought back to the Walla Walla District Headquarters building.
Mastodons lived in the Pacific Northwest long before people did. The mastodon jawbone that was found is estimated to be between 5 and 8 million years old, based on the level of mineralization of the bone and age of nearby geological layers.
Mastodons were ancient elephants that ate leaves and twigs and probably lived in forests. Mastodons were slightly smaller than mammoths, though both are comparable to modern-day elephants, and had a slightly different appearance. For example, mastodons had flatter heads than mammoths and their tusks did not grow as curved.
Teeth were another difference. Mammoths were mainly grass eaters and had flat, plate-like teeth. Mastodons ate woodier vegetation, a diet leading to the cone-shaped ridges of the teeth of the mastodon jawbone found in April.
The fossil will ultimately be displayed at the Ice Harbor Visitor Center. Currently, the jawbone is on loan to Dr. Brett Lenz, Cultural Resources Manager for the Wanapum Heritage Center Repository. Lenz and a team of researchers will be investigating the jawbone to determine the precise species of the mastodon, the age of the fossil, the conditions of its burial and preservation, and a little bit about the individual the fossil belonged to.
“We can look at what’s called the ‘taphonomy’ of what was the bone and understand certain things like the history of what happened after the animal died. Was it rapidly buried or on the surface for a particularly long time? Is there evidence of gnawing on it by rodents or larger carnivores? We can understand a few things like that based on the taphonomy,” Lenz said.
The fossil will be returned to the Corps in January and displayed at Ice Harbor in February.