Figure 2. Map of end moraines (black-shaded polygons) and submerged ridges (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 20,000 to 28,000 years ago, whereas the Harbor Hill-Roanoke Point-Charlestown-Buzzards Bay end moraine represents a retreated ice-sheet position from about 18,000 to 23,000 years ago (Uchupi and others, 2001; Balco, 2011).