From "clean" Ice to "dirty" Ice

The image shows Tasman Glacier in the Southern Alps/New Zealand looking from its accumulation area towards the lower glacier tongue and the currently fast expanding proglacial Tasman Lake. The "clean" ice surface of the main upper glacier trunk of Tasman Glacier (foreground left) contrasts to the increasing supraglacial debris cover on the ice surface as the glacier flows down its valley. The surface of the lower glacier tongue of Tasman Glacier exhibits "dirty ice" and is completely covered by supraglacial debris. Tasman Glacier is characterised by a floating glacier terminus retreating over the proglacial Tasman Lake. Tasman Glacier, the largest individual glacier in the Southern Alps, is a good example of a debris-covered valley glacier landsystem.