Icefalls vary greatly in height. The Roosevelt Glacier icefall, on the north face of Mount Baker (Cascade Range, U.S.), is about 730 metres (2,400 ft) high. The ice cliff of the left side of the ice fall and above the debris covering the glacier is 20 to 40 metres (70 to 140 ft) high. Typical of mountain glaciers, this icefall forms as the ice flows from a high elevation plateau or basin accumulation zone to a lower valley ablation zone. Much larger icefalls may be found in the outlet glaciers of continental ice sheets. The icefall feeding the Lambert Glacier in Antarctica is 7 kilometres (4.4 mi) wide and 14 kilometres (9 mi) long, even though the elevation difference is only 400 metres (1,300 ft), a little more than half that of the Roosevelt Glacier icefall.