Workers preparing a site for bridge replacement have uncovered an old campsite that gives a glimpse of what Minnesota might have looked like 8,000 years ago.

Workers preparing a site for bridge replacement have uncovered an old campsite that gives a glimpse of what Minnesota might have looked like 8,000 years ago.

The rare campsite was recently discovered along the Minnesota River while workers prepared for the $54 million replacement of the Highway 101 bridge that links Carver County and Shakopee, the Star Tribune reported Monday. Federal rules require crews do an archaeological survey before such projects begin to see if anything of historic value would be disturbed.

The artifacts were found 10 to 12 feet below the ground in an area mostly covered by swamp.

"Basically, it's like a time capsule — a very well-preserved record left pretty much intact of where it was deposited," said archaeologist Frank Florin, principal investigator at the site. "It's exciting to know that you're looking at things as they were 8,000 years ago, essentially."

Back then, the land was covered with prairie grasses. Lakes were mere waterholes, and rivers were streams. Small groups of no more than 20 people roamed the wild and camped in river bottoms, close to water, fish and game. They hunted bison that were 50 percent larger than the species of today.

Minnesota state archaeologist Scott Anfinson said campsites like this are rare, because over the centuries, the climate became wetter, river bluffs eroded and campsites were filled in as wetlands. The depth and lack of oxygen preserves stones and tools. Organic material such as plants can also be analyzed and dated.

"We can actually say, 'This spearhead was made by these people who lived at exactly this time,' so we can get a huge amount of information," he said.

Florin said it appears some of the stones used as tools are from North Dakota or western Wisconsin, suggesting that the native people traveled to hunt or trade with other groups.

Craig Johnson, archaeologist for the Minnesota Department of Transportation, said part of the ancient campsite will be destroyed to install deep footings for new bridge piers next year. An excavation is planned for this fall to retrieve artifacts.

"We don't have more than about a half a dozen of these archaeological sites from this period that are known in the Minnesota River Valley, so this is pretty significant," he said.

In their initial work, Florin and his crew used soil core augers — similar to post-hole diggers with extensions — to remove samples of soil and clay and screen them for artifacts. The team hand-drilled about 600 holes last fall and this spring.

"We found evidence for making stone tools, butchering and processing animals, and we found one fire hearth," Florin said. The crew also found spear-point fragments, hide-scraping tools, and remains of turtles, fish and bison.

Carver County road officials are working with the archaeologists to determine the location, scope and budget for this fall's larger excavation. Johnson said it will largely be a rescue operation to retrieve materials from what an area that seems to have the highest concentration of artifacts.

The findings will be numbered, cataloged, photographed and analyzed with a written report, he said, and will likely be archived at the Minnesota Historical Society.