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Ancient Stone "Tools" Found; May Be Among Americas' Oldest

Stefan Lovgren
for National Geographic News
February 15, 2007
 
Crude stone "tools" found in northern Minnesota may be at least 13,000 years old, a team of archaeologists recently announced.

The discovery, if confirmed, would put the objects among the oldest human artifacts ever found in the Americas.

The team found about 50 such objects during a routine survey for road construction in the town of Walker, about 30 miles (48 kilometers) northeast of Park Rapids (see a Minnesota map).

The finds include what appear to be a large hammerstone, beveled scrapers, rudimentary choppers, a crude knife, and numerous flakes that could have been used for cutting.

"We were certainly very surprised to find these objects here," said Matt Mattson, a biologist and archaeologist who has worked extensively with the Leech Lake Heritage Sites program, based near Cass Lake, Minnesota.

But the late Ice Age relics still need to be positively dated and confirmed as human-made before the stones' significance can be established, Mattson and other experts caution.

David Meltzer is an archaeologist at Southern Methodist University in Texas. He said that "there's simply no way to gauge the significance of the discovery until some reliable dates are obtained, and until it's shown that these are truly artifacts."

Choppers and Scrapers

Archaeologists from the Leech Lake Heritage Sites program—a for-profit company owned by the Leech Lake Band of Ojibwe Indians—had been hired by Walker government officials to help evaluate the future site of a new community center.

Led by program director Thor Olmanson, the team discovered the ancient stones underneath a band of rock and gravel on a forested hill.

The team believes the items may be between 13,000 and 15,000 years old, based on the surrounding soil deposits.

"The only thing we have to go by for dating right now is this association with the glacially derived soil," Mattson said.

The scientists believe the tools were human-made, Mattson said, as opposed to having being chipped by glacial movements.

"We have trouble attributing this [chipping] to natural geological forces," he said.

"The pieces have been consistently worked … . Combine that with the number of artifacts that we have in a confined area and it starts to look statistically at odds with a natural occurrence."

Minnesota Oasis

Most scientists believe the first humans entered North America from Asia via a land bridge to Alaska at least 15,000 years ago.

(Related news: "First Americans Arrived Recently, Settled Pacific Coast, DNA Study Says" [February 2, 2007].)

According to one theory, the first Americans initially spread into the continent along a coastal route.

The oldest human remains found in Minnesota date back to about 9,000 years ago and were discovered in 1933 near the western town of Browns Valley.

"If the [newly discovered] site does indeed prove to be 13,000 years old, it would indicate human movement into cooler latitudes during terminal Pleistocene times," said Tom Dillehay, chair of the anthropology department at Vanderbilt University.

The Pleistocene epoch lasted from 1.8 million years ago to 11,500 years ago. Shifting glaciers covered much of Minnesota at the time.

But some researchers have suggested that the north-central part of the state may have been something of an "oasis" 13,000 years ago—an area free of ice cover, with an access route to the southeast.

"The best glacial models that we have now indicate that the central part of Minnesota might have been viable for human occupation earlier than some of the rest of it," Minnesota-based archaeologist Mattson said.

"There are certainly things to be learned about the habitability of certain areas of Minnesota, which would open up the potential for more thorough testing of other similar or viable landforms related to a period of time that is not well understood," Mattson added.

The archaeologists hope that the Minnesota site, which lies in the path of a major city development project, can be preserved and further excavated.

The team also wants to use a geologic dating technique known as optically stimulated luminescence (OSL) to more directly determine the age of the objects.

Meltzer, the Southern Methodist University archaeologist, said he will reserve judgment until the objects have been dated and more is known about them.

"One hates to rain on the parade," he said, "but we've been down this road before—claims of great antiquity that fizzle—and have learned the hard way to be wary."

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