Southern Alps - Location and Description

Location and Description

The Southern Alps run 450 km north to south. The tallest peak is Aoraki / Mount Cook, the highest point in New Zealand at 3,754 metres (12,316 ft) and there are sixteen other points in the range that exceed 3,000 metres in height. The mountains are cut through with glacial valleys and lakes. According to an inventory conducted in the late 1970s, the Southern Alps contained over 3000 glaciers larger than a hectare, the longest of which – the Tasman Glacier – is 29 kilometres in length down towards Lake Pukaki. A chain of glacial lakes are found on the eastern side of the ridge from Lake Coleridge in the north to Lake Wakatipu in Otago in the south.

Settlements include Maruia Springs, a spa near Lewis Pass, the town of Arthur's Pass and some lakeside resorts.

The Southern Alps were named by Captain Cook on March 23, 1770, who described their "prodigious height". They had previously been noted by Abel Tasman in 1642, whose description of the South Island's west coast is often translated as "a land uplifted high".

The Southern Alps lie along a geological plate boundary, part of the Pacific Ring of Fire, with the Pacific Plate to the southeast pushing westward and colliding with the northward-moving Indo-Australian Plate to the northwest. Over the last 45 million years, the collision has pushed up a 20 km thickness of rocks on the Pacific Plate to form the Alps, although much of this has been eroded away. Uplift has been fastest during the last 5 million years, and the mountains continue to be raised today by tectonic pressure, causing earthquakes on the Alpine Fault. Despite the substantial uplift, most of the relative motion along the Alpine Fault is sideways, not vertical.

The climate is cold with snow and ice year-round at the highest points.

Because of its orientation perpendicular to the prevailing westerly winds, the range creates excellent wave soaring conditions for glider pilots. The town of Omarama, in the lee of the mountains, has gained an international reputation for its gliding conditions. The prevailing westerlies also create a weather pattern known as the Nor'west arch, in which moist air is pushed up over the mountains, forming an arch of cloud in an otherwise blue sky. This weather pattern is frequently visible in summer across Canterbury and North Otago. The 'Nor'wester' is a foehn wind similar to the Chinook of Canada, where mountain ranges in the path of prevailing moisture laden winds force air upwards, thus cooling the air and condensing the moisture to rain, producing hot dry winds in the descending air lee of the mountains.