The New York Bight consists of two shelf sectors: (1) New Jersey shelf, trending NE-SW; and (2) Long Island shelf, trending east-west, which are separated by the Hudson shelf valley (extending southeast from outer New York Harbor to the Hudson apron at the shelf edge near the head of the Hudson submarine canyon). Although the present shoreline configuration of the bight results from the Holocene submergence, 2 important earlier developments include post-Miocene uplift of the Appalachians and especially of New England, and Quaternary glaciations.

During the Pliocene, uplift inland created the present regional dips of the coastal-plain strata and supplied sediment to fans which prograded a thin sheet of gravel across the marine coastal-plain formations. There followed a great drop in base level and deep cutting of major river valleys. The inner cuesta and adjoining inner lowland of the coastal plain, part of which is now filled by the water of Long Island Sound, were formed and large quantities of sediment built the shelf edge seaward. Erosion in submarine canyons was especially active at this time.

During the Pleistocene, in connection with continental glaciations, many changes of base level and climate occurred. During the Wisconsin Stage, ice flowing from about N20°W deposited 2 prominent terminal moraines atop Long Island's coastal-plain cuesta--the Ronkonkama (older and more southerly) and Harbor Hill (younger and more northerly) moraines. During each deglaciation, wide outwash plains spread across parts of what is now the Long Island shelf and extensive lakes floored by varved clays formed north of each moraine ridge. Rapid drainage of these moraine-dammed lakes through the Narrows (between Staten Island and Brooklyn) is thought to have been responsible for final erosion of the Hudson shelf valley and for major deposition on the Hudson apron.

As the sea transgressed across sandy outwash (Long Island shelf) and fluvial gravels (New Jersey shelf), it formed barrier chains and reworked the sediments. During parts of the submergence, some barrier chains retreated progressively landward, and the surf zone reworked all shelf sediments. At other times the barriers were drowned in place.

End_of_Article - Last_Page 780------------