Earth Observations taken by the Expedition 21 Crew

ISS021-E-015243 (25 Oct. 2009) --- Upsala Glacier, Argentina is featured in this image photographed by an Expedition 21 crew member on the International Space Station. The Southern Patagonian Ice Field of Argentina and Chile hosts some of the most spectacular glaciers in the world, and is second only to Antarctica in size. This detailed photograph illustrates the terminus of Upsala Glacier, located on the eastern side of the ice field. This glacier is the third largest in the Southern Patagonian Ice Field and, like most other glaciers in the region, has experienced significant retreat over the past century. This image was taken during spring in the Southern Hemisphere, and calving of icebergs ? release of chunks of ice from the glacier terminus as it enters the waters of Lake Argentina - is visible at left. Two icebergs are of particular interest, as they retain fragments of the moraine that forms a dark line along the upper surface of the glacier. Moraines of the type visible in this image are formed from coarse rock and soil debris that accumulates along the front and sides of a flowing glacier; much like a bulldozer blade pushes material in front of it. When two glaciers merge together (center), debris in moraines along their edges can now form a medial moraine that is drawn out along the upper surface of the new ice mass. These moraines can be carried intact to the terminus and included in icebergs that then float away, dropping the coarse debris as the iceberg melts. While the icebergs produced by Upsala Glacier do not reach an ocean, there are many current glaciers ? as well as glaciers and ice sheets that existed in the geologic past ? capable of producing ocean-going icebergs. This process is thought to be recorded in the geologic record as layers or lenses of coarse, land-derived sediments within finer grained sea floor sediments that are located far from any current (or former) coastline.