Effects of Rising Sea Level on the Boston Harbor Islands
Department of Earth Sciences
Department of Geology
Delivered at 2003 Boston Harbor Islands Science Symposium.
Boston Harbor contains one of the few drumlin coasts in the world. The drumlins formed during the late Wisconsinan stage of glaciation and were drowned by rising sea level during the Holocene transgression approximately 5,000 years ago. Modification of the drumlins accelerated as rising sea level encroached upon the island shorelines. Storm waves attacked the base of the drumlins, causing mass wasting and slumping of sediment downward. The mobile silt and clay were removed from the shoreline and deposited in low energy environments. The fine gravel and sand were transported along shore forming beaches, spits, and beach ridges. The former extent of the drumlin is defined by a boulder-lag pavement.