AUBURN, Maine (AP) — 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.

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.