Franz Josef Glacier
Franz Josef Glacier descends to just 250 metres above sea level
amidst the greenery and lushness of a temperate rainforest.
Of all the accessible temperate glaciers in New Zealand, the
Franz Josef Glacier is easily the steepest and fastest moving.
While many glaciers world-wide have been retreating, the Franz
Josef Glacier still flows almost to sea level, through a temperate
rainforest of ancient podocarp trees and other evergreen species.
This combination of ice and temperate rainforest is a unique
feature of New Zealand's glacier country, and is an ecosystem
found nowhere else in the world.
South Westland is situated at 43.5 degrees south, equivalent in latitude to the south of France. Cannes, for example, is the same distance from the coast as Franz Josef, with mountains of similar altitudes. Obviously there are no glaciers that extend down to sea level in France, so why does it happen here?
Running through Franz Josef is the Alpine Fault. Along this fault line the Southern Alps have been pushed up, and continue to rise in close proximity to the ocean. The weather that flows on to the West Coast is forced to rise over the Southern Alps, thereby cooling and dropping most of its moisture as rain and snow. This process causes up to 30 metres of snow to fall on the neve (or catchment area of the glacier), every year.
Snow that is compacted on the neve forms blue glacier ice that is funnelled down the Waiho Valley. The ice flows under its own momentum, forming a 'river of ice'. Although the terminal face of the glacier is continually melting, this is replaced by glacier ice flowing down from the neve. This is aided by basal sliding, caused by a layer of water beneath the glacier which is formed by the weight of the ice pushing against the valley floor.
The glacier slides forward at rates up to 10 times faster than most valley glaciers, presenting the visitor with a spectacular and unique icefall of crevasses, pinnacles, ice caves and canyons.
