"A glacier is a large, slow moving river of ice, formed from compacted layers of snow, that slowly deforms and flows in response to gravity. Glacier ice is the largest reservoir of fresh water on Earth, and second only to oceans as the largest reservoir of total water. Glaciers cover vast areas of polar regions but are restricted to the highest mountains in the tropics. (...) learn more

The terminal lake

With the effects of global warming taking their toll on New Zealand glaciers, it is obvious that their retreat is imminent. Now approximately 27 kilometres long and 600 metres deep the Tasman Glacier is melting and calving at an exponentially increasing rate. In recent years the Tasman Glacier has changed from a 'melting' to a 'calving and melting' terminus, resulting in a terminal lake that is rapidly increasing in size.

This results in icebergs of every shape and size imaginable periodically tearing away from the terminal wall of the glacier into the rapidly growing lake below. On either side of the Terminal Lake, lateral moraines rear up 100 metres to remind us of the scale and greatness the glacier has reached in previous times – the last ice age finishing in just 1890!

The rocky insulation layer

As the glacier continues to retreat in length it also down wastes in height. This meltdown results in an accumulation of debris originating from within the glacier to be left marooned atop the huge river of ice. The layer of rock on top of the glacier provides some spectacular rock fall as the ice continually melts away from beneath. There is no doubt as to the dynamic nature of the dirty end - the working end of the glacier. Although a surprise to many, the messy array of dirty moraine on top of the Tasman Glacier isn't such a bad thing….This layer of rubble acts as an insulator for the ice below, protecting it from the harsh sun's rays and assisting in the preservation of what is undoubtedly the most precious resource on earth – water!

Further glacier information