Present day geomorphic processes on Long Island include rapid trimming of the coastline and caldera wall by wave action. Deep, rapidly eroding linear gullies cut in the youngest pyroclastic deposits expose numerous sections which allow reconstructions of the island's recent eruptive history.
Deposits from three major Plinian and Pelean pyroclastic eruptions dated at approximately 16,000, 4,000 and 200–300 radiocarbon years bp have been recognised. These phases of cataclysmic activity, probably with associated caldera collapse, were separated by numerous intermittent tephra falls many of which would have been heavy enough to destroy much of the physical environment of the island. Interpretation of the pyroclastic deposits erupted during the period of human occupation provide information about changes in the physical environment