The exposed bedrock of Bailey Island is mostly metamorphosed volcanic and sedimentary rocks that were deposited about 450 million years ago. The rusty brown weathering layers are schist, while the light gray interbedded layers are quartzites. The two types of rock are interbedded, meaning that the sediment source varied over time.
During a mountain-building event, the sediments were buried deep in the earth. High temps and pressure changed and deformed the rock.
Bailey Island, Maine