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National Geographic Explorer and photographer Kiliii Yüyan’s journey continues at the Whaleback Shell Midden State Historic Site, a state park in Damariscotta, Maine. Here, the remnants of ancient oyster shells provide a reminder to visitors that rivers have been a source of life here for thousands of years. Come back next week to see more of Kiliii's adventures in our Maine Mondays series. #NationalGeographic #Maine #KiliiiYüyan