In the 1980s, Thomas Bennett went on his first archaeological dig on Yarmouth’s Moshier Island. He didn’t have a degree in archaeology, but he’d taken some classes on it in college and it intrigued him.

Since then, Bennett, director of Prince Memorial Library in Cumberland, has been on digs all over Maine and Massachusetts and in Arizona. He has authored articles for the Maine Archaeological Bulletin and gives presentations, including at his library.

“I enjoy discovering something that potentially hasn’t been touched in 2,000 years or 3,000 years and has something to say about the culture that was in place at that time,” said Bennett.

The joy of discovery spurred Bennett to study coastal shell middens, ancient shell dumping grounds that can also contain fish remains, tool fragments and even pieces of pottery on the coast and the islands of Maine. The middens can provide a wealth of information on the history of the area, including how the environment has changed over the years.

Bennett’s research is aimed at highlighting the impact of climate change on Casco Bay.

“The sea level is rising, and storms are getting more frequent and more destructive,” Bennett said. “You can see the erosion taking effect from year to year.”

Prince Memorial Library received an Island Institute grant last year, which allowed Bennett to contribute to public education on shell middens, and to revisit middens that were inventoried back in the 1970s-80s. This year, it received a Maine Sea Grant to continue that work.

Bennett will put this year’s grant toward a stable isotope analysis on 15 shells from digs on Casco Bay. Each shell has the potential to tell scientists how warm and how acidic the water was when the shell was harvested.

“Theoretically, we can learn a lot about how the Casco Bay environment has changed over time by looking at these archaeological sites and what they hold,” Bennett said.

Greely High School sophomore Aila Robinson has been assisting Bennett, counting soft shell clam hinges, scanning photos and inventorying artifacts from digs.

“The experience has been enlightening,” Robinson said. “I’ve never seen a moose, but I’ve held moose bones in my hand.”

Like Bennett, Robinson is intrigued by the idea of finding artifacts from long ago. She’s also interested in the scientific aspects of finding bones, and working with Bennett has allowed her to learn more about the field of archaeology.

“Archaeology offers clues to our human past,” Robinson said. “That’s incredible.”