Currently, continental glaciers exist in only two areas, Greenland and Antarctica. In both areas, the ice is more than 3000 m thick in the central areas, becomes thinner toward the margins, and covers all but the high est mountains (Figures 17.5 and 17.6). The areal extent of the continental glacier in Greenland is more than 1,800,000 km2, and the East and West Antarctic Glaciers merge to form a continuous ice sheet covering