Glacier National Park, Montana. Low clouds pour over the Continental Divide in Sperry Basin in Glacier National Park. A remnant of the once-massive Sperry Glacier fills the basin above and provides meltwater for Avalanche Lake thousands of feet below. The deep valleys of the Lewis Range were buried beneath thousands of feet of ice during the height of the Pleistocene Epoch which ended approximately 12,000 years ago. The glaciers after which this park is named are quickly melting and are expected to disappear completely within 20 years.