Glacial Valleys

Franz Josef Glacier

Beautiful pastel colours of the sunset above Franz Josef Glacier photographed from Centennial Hut toward the Tasman Sea visible on a horizon. Tusk Rocks in a foreground, Chamberlin Snowfield right, Agassiz Glacier left - Westland National Park, West Coast, New Zealand

The most destructive and powerful hand of Mother Nature lies, arguably, in the cryosphere. We may not see it doing much immediate damage, but by observing the landscape we can see enormous changes in our environment caused by glaciers. One of the very typical and most visible footprints glaciers leave behind are our, often ice free, valleys. Entire mountainsides were remodeled by

glacial action leaving only steep valley walls behind. In the upper reaches of the Franz Josef Glacier there is massive pressure from the build up of up to 300m of ice and snow. Associated erosional forces combine to create a bowl shaped depression in the underlying rock called a Cirque, with the snow and ice field contained in the cirque being called the Neve. As gravity encourages ice down the valley the weight of the ice presses downwards and outwards scouring the valleys into a distinctive glaciated U-shape. These are much broader and flatter floored than the V-shaped valleys carved by rivers.

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