Figure 2. Map of end moraines (black-shaded polygons) and submerged ridges associated with the offshore extensions of these moraines (dashed lines) in southern New York and New England (modified from Gustavson and Boothroyd, 1987) along with the study area (red-outlined polygon). The Ronkonkoma-Block Island-Nantucket terminal moraine represents the maximum advance of the Laurentide Ice Sheet about 25,500 to 28,100 years ago, whereas the Harbor Hill-Roanoke Point-Charlestown-Buzzards Bay end moraine represents a retreated ice-sheet position from about 20,400 to 22,400 years ago (Balco, 2011).