The Fox and Franz Josef Glaciers cut through dramatic glacial valleys to flow into temperate rainforest. While many glaciers world-wide have been retreating, these glaciers still flow almost to sea level, making them unique relics of the last Ice Age.
South-Westland lies in the path of a band of wind known as the ‘roaring forties’. 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 approximately 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 valleys of the Franz Josef and Fox Glaciers. This flows under its own momentum, forming these ‘rivers of ice’ which are easily accessible from the Waiho (Franz Josef) and Cook (Fox) river beds.
Although much melt occurs from the surface of the glaciers at lower elevations (the ablation zone), this high snowfall continues to push ice down the valleys at very high rates. This is aided by basal sliding, caused by a layer of water beneath the glaciers, formed by the weight of the ice pushing against the valley floor. Both of these factors cause the Franz Josef and Fox Glaciers to have flow rates that are up to 10 times faster than most valley glaciers.
The glaciers flow over large bedrock steps on the valley floors. This causes the ice to extend and break up, forming steep icefalls that are mazes of crevasses and pinnacles of ice. Spectacular views of this dramatic landscape are gained from short valley walks to the Franz Josef and Fox Glacier terminal faces, or by taking a guided walk on to the ice. Either option will provide any visitor with a unique glacier experience.