Glaciers and Icebergs in New Zealand.

26/05/10

Many people imagine that glaciers and icebergs are predominantly white, mainly as this is what you see in images of the Artic and Antarctic where the snow and ice have been formed from the freezing of clean water.

However, the inland glaciers of New Zealand are formed high in mountains and as they travel down towards the sea, they collect debris and therefore much of them look ‘dirty’, especially at their front ends. But this ‘debris provides some amazingly beautiful striations and other visually appealing designs, which make these glaciers quite remarkable and much more interesting than their ‘clean’ counterparts.

These designs can be seen in my images of the Tasman glacier and lake in Aoraki Mount Cook national park on the South Island in New Zealand.

This glacier is two-million-year-old, 27km long, 4km at its widest part and 600metres deep in parts. It ends in a terminal lake which began forming in 1973 and the glacier’s retreat has noticeably quickened because the lake is expanding all the time and is causing a more rapid melt of the terminal face.

The Tasman flows south from the southern slopes of the Minarets peak, along the eastern flank of Aoraki/Mount Cook, the peak of which is only five km from the glacier. It is almost met near its end by the meltwater of the Murchison Glacier, which approaches from the northeast before turning to flow beside the Tasman Glacier outside the moraine wall.

The waters from both these glaciers pool at the end of the glacier in Lake Tasman, before flowing south to join the outflow from the nearby Hooker and Mueller Glaciers in the wide valley of the Tasman River, whose braided streams flow south into Lake Pukaki. They eventually flow into the Waitaki River and to the Pacific Ocean north of Oamaru.

The terminal face of the Tasman glacier is in quite an active phase at the moment with a huge slab of ice, measuring around 250m by 250m wide by 80m high, ‘calved’ into the lake last year causing a three-metre high wave to surge down the lake. A second iceberg about quarter of the size slipped off the face shortly afterwards.

It is predicted that the glacier will eventually disappear with the new lake that is formed reaching a maximum in another10-19 years. In 1973 there was no lake and by 2008 a lake that was 7km long, 2km wide and 245m deep existed at the glacier end.