The last two aerial photographs in this group of five document changes that occurred during the 69 years between June 1937 and July 28, 2006. Both photographs are taken towards the north and show the retreating, calving, tidewater terminus of Yale Glacier, located at the head of Yale Arm, College Fiord, Prince William Sound, Alaska. In 1937, Yale Glacier’s terminus was located at about the same position that it occupied when it was visited by the Harriman Alaska Expedition in 1899. A stream of icebergs issues from several embayments cut into the approximately 45 meter (148 feet) high face on the east side of the terminus. Several current and former tributary valley glaciers descend the east wall of the fiord. The two closest to the terminus have lost contact with Yale Glacier. Except for the moraine-covered ice on both margins of the glacier, snow still covers most of the lower reaches of the glacier. (B. Washburn, #122, courtesy of National Snow and Ice Data Center). During the intervening 69 years between photographs, Yale Glacier has retreated as much as 6 kilometers (3.7 miles), with most of the retreat occurring post-1957. The width of the tidewater part of the terminus of the glacier is much less than half of what it was in 1937. Yale Glacier has thinned substantially, in places by more than 250 meters (820 feet). All of the eastern tributaries have retreated and lost contact with Yale Glacier. An island and a large area of glacially sculpted bedrock have emerged from beneath the retreating glacier. Retreat of the land-based western portion of the terminus has kept pace with the retreat of the eastern tidewater portion of the glacier. A well-developed trimline is visible on the west side of the glacier. The 2006 photograph was made from an altitude of approximately 3,200 meters (10,500 feet), while Washburn’s, 1937 photograph was made from an altitude of more than 5,200 meters (17,050 feet). (USGS Photograph by Bruce F. Molnia).
