Washington, June 9 : Researchers at the University of Michigan in the US have found the first archeological evidence of human activity preserved beneath the Great Lakes.

The researchers located what they believe to be caribou-hunting structures and camps used by the early hunters of the period more than 100 feet deep in Lake Huron, on a wide stoney ridge that 9,000 years ago was a land bridge.

"This is the first time we've identified structures like these on the lake bottom," said John O'Shea, curator of Great Lakes Archaeology in the Museum of Anthropology and professor in the Department of Anthropology.

"Scientifically, it's important because the entire ancient landscape has been preserved and has not been modified by farming, or modern development. That has implications for ecology, archaeology and environmental modeling," he added.

O'Shea and Meadows found features that they believe to be hunting pits, camps, caribou drive lanes and stone piles used to attract the caribou to the drive lanes.

Drive lanes are long rows of rocks used to channel caribou into ambushes. The 1,148-foot structure they believe is a drive lane closely resembles one on Victoria Island in the Canadian subarctic.

The hunting formations are on the 10-mile-wide Alpena-Amberley ridge that stretches more than 100 miles from Point Clark, Ontario to Presque Isle, Michigan.

The ridge was a bridge between 10,000 and 7,500 years ago when water levels were much lower. Its surface is relatively unspoiled, unlike coastal areas where scientists believe other archeological sites exist.

These coastal sites would now be deeply covered in sediment, so they're often considered lost forever.

Scientists have hypothesized for some time that the ridge might hold signs of ancient occupations. But they didn't know what signs to look for.

O'Shea and Meadows zeroed in on caribou-hunting structures after considering the region's climate at the time, which would have been similar to the subarctic.

Subarctic hunters are known to utilize caribou drive lanes.

The U-M researchers then narrowed down where to look for these structures by modeling the lake ridge as it would have been when it was dry.

Perhaps more exciting than the hunting structures themselves is the hope they bring that intact settlements are preserved on the lake bottom.

These settlements could contain organic artifacts that deteriorate in drier, acidic soils on land.

"This is why the discovery of sites preserved beneath the lakes is so significant," O'Shea said. (ANI)