Athabasca glacier is only a tiny fraction of this long river of slow-moving ice. The area covered by the Columbia Icefields is enormous: the equivalent of 80 Stanley Parks. The ice is deep too -- in places 300 metres, or as deep as the Eiffel Tower is tall.
One of three tri-continental divides in North America, Snow Dome (right) peeps over the rough moraine created by the slow steady grind of glacial movement. From this continental roof, water flows downward to three oceans: Pacific, Arctic and Atlantic.