One of the most spectacular features in the park, next to the massiveness of Mt. McKinley, is the dramatic "Great Gorge" of the Ruth Glacier. The upper Ruth Glacier, which is almost 3 vertical miles below the summit of Mt. McKinley, catches all of the snow that falls on the southeast side of the mountain. The snow and ice that accumulate in this area are squeezed through the one-mile-wide bottleneck of the Great Gorge. Through this gorge, the glacier drops nearly 2,000 feet over ten miles and is raked with crevasses. Buttressed on either side by solid granite cliffs that tower 5,000 feet above the glacier's surface, this gorge is not only a spectacular sight, but offers world-class challenges for mountaineers. In 1983, researchers from the University of Alaska found the depth of the ice within the gorge to be more than 3,800 feet. Combined, the depth of the glacier and the height of the towering cliffs create an abyss that is deeper than the Grand Canyon. If the glacier melted and you dropped a coin from the top of Mt. Dickey, it would fall for more than one and a half miles before coming to a rest in the bottom of this gorge. The glacier, which now stops the coin after traveling only a mile, moves at an impressive speed of 3.3 feet per day, At this rate, 4 million pounds of ice may flow into and out of the gorge daily! Will Harrison, a glaciologist who has worked in the gorge, relates his experience: "Usually at the margin of a glacier you can find a place to set a surveyor's prism. On west side of the gorge you could not. The walls there were smooth and not just vertical, but overhanging! It's amazing to think of how overhanging cliffs that tall could be created."