Figure 10. Map, modified from Stone and Borns (1986) and Gustavson and Boothroyd (1987), showing locations of end moraines (black polygons) in southern New England and on Long Island, New York. The Ronkonkoma-Nantucket moraine marks the Laurentide ice sheet's maximum southern extent about 20–28 thousand years ago, and the Harbor Hill-Roanoke Point-Charlestown-Buzzards Bay-Sandwich moraine represents the ice-sheet position after a readvance around 18–22.5 thousand years ago (Uchupi and others, 1996; Balco, 2011). Underwater extensions of the moraines are shown as dashed lines. Study area is shown as a red polygon.