Date of Award
Master of Science in Geology
Geography and Marine Affairs
The cuspate shoreforms of the lower West Passage, Narragansett Bay, are similar in configuration. They are triangular in shape, enclose a central lagoon and extend seaward from the mainland into West Passage. Two of these cuspate shoreforms, Greene Point and Casey Point, were selected for field investigation to determine their morphologic and sedimentologic response to the littoral environment.
Greene Point is partially composed of fine sediments ranging from silt to pebble sizes, which are easily set in motion by waves under normal meteorologic conditions. The beach morphology of this shoreform undergoes significant seasonal variations. In addition, this beach has apparently been retreating over lagoonal deposits which are now partially exposed on the foreshore. The cobble and boulder size material forming portions of the lower foreshore of Greene Point are not normally transported by waves and have lagged behind the retreating portion of the beach.
In contrast, the Casey Point beach shows little seasonal change. Shape sorting of the cobble and boulder size material forming the beach indicates, however, that the surficial sediments are at least occasionally reworked by waves.
The extremely coarse material included in the cuspate shoreforms along West Passage was glacially derived and deposited at or near the location of the present shoreforms during the last glacial age. After post-glacial transgression and establishment of a marine environment along West Passage this material was probably reworked by waves into the present morphology of the shoreforms. The cuspate configuration of the shoreforms is due to shoreline orientation perpendicular to maximum effective fetch in West Passage.
Zarillo, Gary A., "CUSPATE SHOREFORMS OF WEST PASSAGE NARRAGANSETT BAY, RHODE ISLAND" (1975). Open Access Master's Theses. Paper 2019.