GLACIER NATIONAL PARK

national park set in a scenic Rocky Mountain wilderness in northwestern Montana, U.S., adjoining the Canadian border and Canada's Waterton Lakes National Park. The two parks together compose the Waterton-Glacier International Peace Park, dedicated in 1932. Glacier National Park was established in 1910 and encompasses 1,013,572 acres (410,178 hectares). The park has many active glaciers. Mountains, lakes, cirques, and valleys all show the effects of the ice sheet that formerly covered the region. The park straddles the Continental Divide (great ridge of the Rocky Mountains that marks the boundary between westward Pacific drainage and eastward Atlantic drainage), with the forests concentrated on the western slopes because of the heavier rainfall there. Alpine meadows that blossom with wildflowers in summer are common at higher elevations. park in southeastern British Columbia, Canada, lying in the heart of the Selkirk Mountains, within the great northern bend of the Columbia River, east of Revelstoke. Established in 1886, it occupies an area of 521 square miles (1,349 square km). Majestic snowcapped peaks, such as Hermit, Cheops, Grizzly, Sifton, Grant, Avalanche, and Sir Donald, flanked by immense ice fields and glaciers, form an impressive alpine panorama, with canyons, turbulent rivers, waterfalls, and flower-filled meadows. Outstanding features are the Illecillewaet Glacier, which has an area of 10 square miles (26 square km) and falls more than 3,500 feet (1,100 m) from its nv (partially compacted snow at its upper end), and the Nakimu Caves in the Cougar Valley. The park is crossed by the Canadian Pacific Railway and the Trans-Canada Highway. The great ice sheets Two great ice masses, the Antarctic and Greenland ice sheets, stand out in the world today and may be similar in many respects to the large Pleistocene ice sheets. About 99 percent of the world's glacier ice is in these two ice masses, 91 percent in Antarctica alone. Antarctic Ice Sheet Dimensions The bedrock of the continent of Antarctica is almost completely buried under ice. Mountain ranges and isolated nunataks (a term derived from Greenland's Inuit language, used for individual mountains surrounded by ice) locally protrude through the ice. Extensive in area are the ice shelves, where the ice sheet extends beyond the land margin and spreads out to sea. The ice sheet, with its associated ice shelves, covers an area of 13,918,000 square kilometres (5,374,000 square miles); exposed rock areas total less than 200,000 square kilometres. The mean thickness of the ice is about 2,100 metres (6,900 feet), and the volume of ice more than 29 million cubic kilometres (7 million cubic miles). The land surface beneath the ice is below sea level in many places, but this surface is depressed because of the weight of the ice. If the ice sheet were melted, uplift of the land surface would eventually leave only a few deep troughs and basins below sea leveleven though the sea level itself also would rise about 80 metres from the addition of such a large amount of water. Because of the thick ice cover, Antarctica has by far the highest mean altitude of the continents (2.2 kilometres [1.4 miles]); all other continents have mean altitudes less than 1 kilometre (0.6 mile).