AUBURN, Maine —  An archaeological survey made necessary by an airport construction project has uncovered parts of ancient tools that are thought to date back 9,000 to 11,000 years.

When an archaeologist pulled a pointed brown stone — an inch long and part of an ancient tool possibly used to clean animal skins — from the ground west of the Auburn-Lewiston Municipal Airport in December, it was enough to bring a full archaeological excavation to the site.

Last week, a member of a digging team found another piece of stone tool that dig organizers said matches the first piece.

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Bob Bartone, assistant director of the University of Maine at Farmington's Archaeological Research Center, said his team will continue the dig for the rest of month looking for more tools, stone chips and pieces of charcoal from what was once a large fire pit.

Bartone figures the site dates to the time following the most recent ice age, between 9,000 B.C. and 7,000 B.C. When the glaciers retreated, they would have left behind a wide-open tundra populated by animals and people hunting them.

The excavation, Bartone said, gives more understanding to the those first Mainers.

"The artifacts and their context, their relation to each other across the site and down through the ground is really what helps us piece things together," he said. "You can show me some stone tools and chips at the lab, and it's very interesting. But if I know those things were found in some relationship to each other, it tells me a lot more."

When state construction permits were issued to the airport for a new taxiway, they required an archaeological survey because artifacts previously had been found in the area.

A preliminary dig last fall found prehistoric Indian artifacts that called for a full excavation.

The entire area has been known to archaeologists for years, with at least six dig sites turning up Paleo-Indian artifacts in the square mile surrounding the Auburn airport, Bartone said.

Bartone said he thinks the latest site, on the north side of the airport, is connected to a dig on the south side of the airport a decade ago that turned up stone tools and chips left over from making and sharpening them.