Aoraki / Mount Cook

Aoraki / Mount Cook is the highest mountain in New Zealand. Its height, as of 2014, is listed as . It sits in the Southern Alps, the mountain range that runs the length of the South Island. A popular tourist destination, it is also a favourite challenge for mountain climbers. Aoraki / Mount Cook consists of three summits: from south to north, the Low Peak (), the Middle Peak () and the High Peak. The summits lie slightly south and east of the main divide of the Southern Alps / Kā Tiritiri o te Moana, with the Tasman Glacier to the east and the Hooker Glacier to the southwest.

Location

The mountain is in the Aoraki / Mount Cook National Park, in the Canterbury Region. The park was established in 1953 and along with Westland National Park, Mount Aspiring National Park and Fiordland National Park forms one of the UNESCO World Heritage Sites. The park contains more than 140 peaks standing over and 72 named glaciers, which cover 40 percent of its .

The peak is located at the northern end of the Kirikirikatata / Mount Cook Range, where it meets with the main spine of the Main Divide, forming a massif between the Hooker Valley to the southwest and the Tasman Valley east of the mountain. These two valleys provide the closest easily accessible view points of Aoraki / Mount Cook. A lookout point at the end of the Hooker Valley Track located only 10 km from the peak has views of the entire mountainside.

The settlement of Mount Cook Village, also referred to as "Aoraki / Mount Cook", is a tourist centre and base camp for the mountain. It is 7 km from the end of the Tasman Glacier and 15 km south of Aoraki / Mount Cook's summit.

On clear days, Aoraki / Mount Cook is visible from the West Coast as far north as Greymouth, some 150 kilometres away, and from most of State Highway 80 along Lake Pukaki and State Highway 6 south of Lake Pukaki. The near horizontal ridge connecting the mountain's three summits forms a distinctive blocky shape when viewed from an eastern or western direction.
Another popular view point is from Lake Matheson on the West Coast, described as the "view of views", where on calm days, the peaks of Aoraki / Mount Cook and Mt Tasman are reflected in Lake Matheson.

Local climate

Aoraki / Mount Cook receives substantial orographic precipitation throughout the year, as breezy, moisture-laden westerly winds dominate all year-round, bringing rainclouds from the Tasman Sea with them.

Annual precipitation around the mountain ranges varies greatly as the local climate is dominated by the eastward movement of depressions and anticyclones from across the Tasman Sea. The Aoraki / Mount Cook massif is a major obstacle to the prevailing westerly winds as they push depressions and associated cold fronts of moist air from the subtropics in the northwest against the mountain range. As the air rises towards the peaks, it expands and cools, and forms clouds. Rain and snowfall are often heaviest around the level and can last for several days if the front is slow-moving.

As a result of the local weather patterns, the western slopes of Aoraki / Mount Cook can receive well over of annual precipitation, whereas the nearby Mount Cook Village, only south of the mountain receives of rain or snowfall.
While the weather on the eastern side of the mountain is generally better, rain or snow can quickly become widespread on that side as well if the wind turns to the south or southeast. This brings with it a rapid drop in temperature and poor visibility, adding to the difficult climbing conditions on Aoraki / Mount Cook.

Temperatures at the mountain's base in the Hooker Valley around range from to , and generally fall just over 1 °C for every 200 metres of altitude.

From about and higher, semi-permanent snow and ice fields exist during winter. Winter and spring are usually less settled than summer and autumn. Anticyclones often bring days of settled weather in summer, or clear cold conditions in winter with severe frost.

Naming and European discovery

' is the name of a person in the traditions of the Ngāi Tahu iwi; an early name for the South Island is ' (Aoraki's Canoe). In the past many believed it meant "Cloud Piercer", a romantic rendering of the name's components: ' (world, daytime, cloud, etc.) and ' or ' (day, sky, weather, etc.). Historically, the Māori name has been spelt ', using the standard Māori form.

Aoraki / Mount Cook became known to Māori after their arrival in New Zealand some time around the 14th century CE. The first Europeans who may have seen Aoraki / Mount Cook were members of Abel Tasman's crew, who saw a "large land uplifted high" (probably some part of the Southern Alps) while off the west coast of the South Island, just north of present-day Greymouth on 13 December 1642 during Tasman's first Pacific voyage. The English name of ''Mount Cook'' was given to the mountain in 1851 by Captain John Lort Stokes to honour Captain James Cook who surveyed and circumnavigated the islands of New Zealand in 1770. Captain Cook did not sight the mountain during his exploration.

Following the settlement between Ngāi Tahu and the Crown in 1998, the name of the mountain was officially changed from Mount Cook to Aoraki / Mount Cook to incorporate its historic Māori name, Aoraki. As part of the settlement, a number of South Island placenames were amended to incorporate their original Māori name. Signifying the importance of Aoraki / Mount Cook, it is the only one of these names where the Māori name precedes the English. Under the settlement the Crown agreed to return title to Aoraki / Mount Cook to Ngāi Tahu, who would then formally gift it back to the nation. Neither transfer has yet occurred; Ngāi Tahu can decide when this will happen.

Geology

The Southern Alps in the South Island were formed by tectonic uplifting and pressure as the Pacific and Indo-Australian Plates collided along the island's western coast. The uplifting continues, raising Aoraki / Mount Cook an average of each year. However, erosive forces are also powerful shapers of the mountains. The severe weather is due to the mountain's jutting into powerful westerly winds of the Roaring Forties which run around approximately 45°S latitude, south of both Africa and Australia. The Southern Alps are the first obstacle the winds encounter after South America, having moved east across the Southern Ocean.

The height of Aoraki / Mount Cook was established in 1881 by G. J. Roberts (from the west side) and in 1889 by T. N. Brodrick (from the Canterbury side). Their measurements agreed closely at . The height was reduced by when approximately 12–14 million cubic metres of rock and ice fell off the northern peak on 14 December 1991.The landslide carried with it another 40 million cubic metres of rock and ice. The impact caused an earth quake of 3.9 on the Richter scale. 207 In search Of Ancient NZ.Campball and Hutching.GNS science/Penguin.2011.
Two decades of erosion of the ice cap exposed after this collapse reduced the height by another 30 m to 3724 m, as revealed by new GPS data from a University of Otago climbing expedition in November 2013.

Aoraki / Mount Cook lies in the centre of the distinctive Alpine Fault, a 650 km long active fault in the Southern Alps. It is responsible for the uplift of Aoraki / Mt Cook and is believed to move every 100 to 300 years. It last moved in 1717.

Surrounding forests and glaciers

The average annual rainfall in the surrounding lowlands, in particular to the west, is around . This very high rainfall leads to temperate rainforests in these coastal lowlands and a reliable source of snow in the mountains to keep the glaciers flowing. These include the Tasman Glacier to the east of the mountain and the smaller Hooker Glacier immediately to its south.

The vegetation in the valleys to the east, in particular the Tasman Valley, is noticeably less lush than that on the western slopes of the mountain. Forest would normally grow to about 1,300 m in this area, but a lack of soil due to scree, rock falls and the effects of glaciation prevent this in most localities around the mountain. Snow tussock and other alpine plants cling to as high as 1,900 m.
Above the snowline, only lichen

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