The first archeological evidence of human activity beneath the Great Lakes has been discovered by researchers from the University of Michigan.

More than 100 feet below the surface of Lake Huron, on a rocky ridge that served as a land bridge about 9,000 years ago, the research team found what is believed to have been caribou-hunting structures and camps used by early hunters.

A paper about the findings is published in the June 8 issue of Proceedings of the National Academy of Sciences.

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

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

O'Shea and Guy Meadows -- director of the Marine Hydrodynamics Laboratories and a professor in the departments of naval architecture and marine engineering, and also atmospheric, oceanic and space sciences -- found features they suspect are the remains of hunting pits, camps and caribou drive lanes, which are long rows of rocks used to channel caribou into ambushes.

The 1,148-foot submerged structure they identified as an animal drive lane closely resembles a drive structure located on Victoria Island in the Canadian subarctic.

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

The ridge was a land bridge between 10,000 and 7,500 years ago, when water levels were much lower, the researchers indicated.

Unlike coastal areas, where scientists contend other archeological sites exist but are buried in seed sediment and likely lost forever, the surface of the newly-discovered hunting ground appears relatively unspoiled.

The scientists say they long suspected they would find signs of ancient occupations along the ridge, but the evidence didn't jump out at them until O'Shea and Meadows began searching for caribou-hunting structures -- which made sense, as the region's climate at the time would have been similar to the subarctic, where hunters were known to utilize caribou drive lanes.

The U-M researchers then narrowed their search further by modeling the lake ridge as it likely would have looked when it was dry, and then using computer programs to reconstruct the ancient environment and then simulate caribou migrations through the area.

After honing in on the areas they wanted to explore, O'Shea and Meadows called out the university's new, Blue Traveler survey vessel, with cutting-edge sonar equipment and remotely-operated underwater vehicles with video cameras.

"The combination of these state-of-the art tools have made these underwater archeological investigations possible," Meadows said. "Without any one of these advanced tools, this discovery would not have happened."

The archaeologists plan to start examining the new hunting areas this coming summer.

Not much is known about the Paleo-Indian and early Archaic periods in the Great Lakes region because most of the period enclaves were covered by the lakes.

"Without the archeological sites from this intermediate time period, you can't tell how they got from point A to point B, or Paleo-Indian to Archaic," O'Shea said. "This is why the discovery of sites preserved beneath the lakes is so significant."