RUAPEHU, MOUNT

Ruapehu, 9,175 ft, the highest mountain in the North Island, is an active volcano lying at the southern end of the Rotorua-Taupo volcanic district in Tongariro National Park. It appears to have had a long active history, and mud-flow debris from Ruapehu was deposited in each of the last three Pleistocene glaciations. Immediately to the north of Ruapehu, forming part of the same coalescing volcanic mass and aligned along a line striking NNE, are the major volcanoes Ngauruhoe and Tongariro. Other volcanic peaks of lesser altitude are numerous. The broad irregular summit area of Ruapehu includes the prominent points of Paretetaitonga, 9,025 ft in the west; Te Heuheu, 9,040 ft in the north; Cathedral Rocks, 8,150 ft in the north-east; Mitre Peak, 8,450 ft in the south-east; Girdlestone Peak, 8,715 ft in the south; and Ruapehu, 9,175 ft in the south-west. Below and between Paretetaitonga and Ruapehu is a crater lake at 8,375 ft occupying the present crater. The high points mentioned are not separate volcanoes but peaks on an irregular crater rim, with East Crater, West Crater, Girdlestone Crater, and Crater Lake as younger and smaller craters contained within the larger. The rocks of which Ruapehu is built are andesites, mainly labradorite and labradorite pyroxenite andesites, with much glass in the ground mass. The andesites are appreciably more basic and of darker colour than those of the Egmont chain of volcanoes.

Although Ruapehu has frequently erupted steam and ash, and Crater Lake is normally warm and sometimes boiling, the only lava eruption during European times occurred in May and June 1945. During this period ash eruptions reached such a degree of violence that ash falls were reported as far away as Wellington, 145 miles distant.

The largest river rising on Ruapehu is the Whangaehu, but it is not of any considerable size, even when it reaches the coast near Turakina to the south of Wanganui. The Whangaehu drains the eastern side of Crater Lake by slow percolation through and beneath an ice dam. From time to time the dam is breached, and the river's importance is considerable in that it has carried several lahars or mud flows from Mount Ruapehu. Lahars have been recorded on 13 February 1861, 1 May 1889, 10 March 1895, in 1903, on 22 January 1925, and 24 December 1953, wrecking a railway bridge immediately prior to the arrival of the Wellington-Auckland Limited express. The train plunged into the river with the loss of 151 lives. This has been called the Tangiwai Disaster. A flood-warning system has now been erected on the river to prevent further occurrences.

Although from about 3,000 ft and upwards Ruapehu is composed predominantly of lavas and ash, the material composing the surrounding countryside is a mass of unsorted andesitic debris ranging from large boulders many feet across to fine mud. The surface of this material is generally smooth except in the north-west, where there are a large number of conical hills. This debris constitutes the ring plain of Ruapehu and was deposited during the Pleistocene glaciations by gigantic lahars from the mountain. The conical mounds were formed by collection of debris around abnormally large blocks when they settled from the lahars.

Today Mount Ruapehu is probably one of New Zealand's most popular mountain resorts, and tourist facilities range from huts to the excellent tourist hotel, the “Chateau”. Ski tows have been installed, and in season many thousands of visitors are often on the mountain at one time.

Ascents of Ruapehu

Because there used to be some doubt as to which of Ruapehu's peaks was the highest, several early explorers claimed to have been first to reach the summit. The position was further complicated because the mountain was sacred to the Maoris and climbers had to conceal the evidence of their attempts from Te Heuheu and the Taupo tribes. In the late 1840s Sir George Grey and the Rev. Richard Taylor climbed some distance up the mountain, and on 30 January 1853 they explored the eastern slopes and appear to have reached the summit icefield. On 12 December 1877 John and Thomas Allison, of Wanganui, climbed to the summit of Te Heuheu Peak (9,040 ft). They were followed, in February 1879, by G. Beetham and J. P. Maxwell, who discovered the crater lake but did not approach closely enough to find that its waters were warm. The first ascent of Paretetaitonga (9,025 ft) was accomplished in 1882 by H. C. Field, a civil engineer from Wanganui. It was left to James Park, C. Dalin, and W. H. Dunnage to ascend Tahurangi (9,175 ft) to the true summit of Ruapehu. On 8 January 1886 this party climbed Girdlestone Peak (8,670 ft) believing that they would then find a quick route to the top of Tahurangi. They were disappointed in this and had to retrace their path with some difficulty before they could make their successful attempt on Tahurangi.

Maori Legend of Mounts Ruapehu and Taranaki (Egmont)

Ruapehu, the beautiful maid, was married to Taranaki. One day, while her husband was away hunting, she was wooed and won by Tongariro. When Taranaki returned at the end of the day he surprised the guilty pair. A titanic battle ensued in which Taranaki was defeated. He retreated towards the west coast, carving out the course of the Wanganui River as he went. When he reached the coast he moved northwards to the western extremity of the North Island, where he rested. There his great weight made the shallow depression which afterwards filled with water and became Te Ngaere swamp. Taranaki, or Egmont, as Cook named him, now sits in silence looking towards his wife and his rival. In spite of her infidelity, Ruapehu still loves her husband and sighs occasionally as she remembers him, while the mist, which drifts eastward from his head, is the visible sign of Taranaki's love for her. For his part, Tongariro, who despairs of ever possessing her again, smokes and smoulders with anger. To this day travellers in the Tongariro National Park see the basin called Rua Taranaki, “the Pit of Taranaki”, which lies to the east of the Tama Saddle which was the original home of Taranaki.

The name Ruapehu does not appear to commemorate any event in Maori legend. Broken into its components it means rua (two) and pehu (to explode or make a loud noise). But this method of breaking down Maori place names in order to explain their meaning is far from reliable.

by Bernard John Foster, M.A., Research Officer, Department of Internal Affairs, Wellington and Thomas Ludovic Grant-Taylor, M.SC., New Zealand Geological Survey, Lower Hutt.

Geology of the Tongariro Subdivision, Bulletin 40 N.S., Geological Survey Department, Gregg, D. R. (1960).