The Charlestown-Green Hill barrier beach-lagoon complex lies along Rhode Island's south shore. Barrier beach and tidal delta sands, lagoonal fine sediments, and lag deposits have been deposited on a base of glacial till, outwash, and glaciofluvial sand. The beach and lagoonal sediments have been derived mainly from reworking of glacial sediments. Tidal currents have built a sand delta at the inshore end of an inlet, but sand on the barrier beach's lagoonal side has been introduced over the barrier. Fine sediments are deposited in the deeper areas of the lagoon. The barrier beach was formed at a lower sea level, and moved landward as the sea transgressed, with lagoonal deposition migrating with the barrier. The small size of this barrier places its base at a shallow depth, resulting in erosion of the entire seaward side by storm waves and also permitting considerable transport of sand across the barrier to the lagoon side. The barrier has remained small because of lack of sand supply. Thus lack of sand supply seems to be the dominant factor in allowing the landward migration of this barrier.
No takes yet. Share an insight, caveat, or question.
William P. Dillon (1970) studied this question.