The circular topography of Pawtuckaway State Park in Nottingham is not a meteor impact crater, as Pembroke resident Stephen Dupuis publicly pondered in a Monitor article yesterday. It is the core of an ancient volcano, said State Geologist David Wunsch. He said the volcano was active in the Cretaceous Period - 100 million to 150 million years ago. Although he said it was good that recent technological breakthroughs made it easier for the public to virtually explore, he also identified a risk.