Where Montana kisses Canada lies a jewel of the US national park system. Glacier's million-acre wilderness is arguably America's most stunning natural environment, with 700 or so wetland areas and lakes, towering peaks, hundreds of waterfalls and - of course - two dozen glaciers. Called by Blackfeet Indians "the backbone of the world," this World Heritage Site straddles the US/Canadian border. Its glaciers carve and reveal prehistoric seas, faults, uplifts and giant slabs of ancient crust - a unique geologic formula for spectacular scenery. Over 700 miles of hiking trails venture into the national park's backcountry - an extreme playground for cross-country skiers, paddlers and climbers. Glacier is also a living laboratory for scientists. They work to understand how a warming climate will change this ecosystem, protect vulnerable aquatic species, track grizzly bears and wolverines, study glacial retreat and fight the devastating impact of a deadly disease on Glacier's mighty pines.

Originally released by National Geographic, 2009. Streaming video file encoded with permission for digital streaming by Infobase on April 07, 2015.

Glaciers Threatened by Warming (7:02); --Scientists Monitor Melt Water (5:49); -- Fisheries Experts Monitor Bull Trout (6:56); -- Warming Affects the Grizzly Bear (7:51); -- Wolverine and Pika Threatened (7:15); -- White Bark Pine Threatened by Fungus (6:57); -- The Collapse of Black Foot Glacier (8:09); .