Geology Of New Zealand. In The Shadows Of Volcanoes

Any visitor to New Zealand can find a variety of awesome landscapes here. Spectacular glaciers, picturesque fiords, rugged mountains, vast plains, rolling hillsides, subtropical forest, volcanic plateau, miles of coastline with gorgeous sandy beaches - it’s all here. Lying in the south-west Pacific, New Zealand consists of two main islands - the North Island and the South Island. In addition, Stewart Island and many smaller islands lie offshore. The North Island of New Zealand has a 'spine' of mountain ranges running through the middle, with gentle rolling farmland on both sides. The central North Island is dominated by the Volcanic Plateau, an active volcanic and thermal area. The massive Southern Alps form the backbone of the South Island. To the east of the Southern Alps is the rolling farmland of Otago and Southland, and the vast, flat Canterbury Plains.

Geology New Zealand's oldest rocks are over 500 million years old, and were once part of Gondwanaland. This massive super-continent started to split up about 160 million years ago, and New Zealand separated from it about 80 million years ago. New Zealand sits on two tectonic plates - the Pacific and the Australian. Fifteen of these gigantic moving chunks of crust make up the Earth's surface. The North Island and some parts of the South Island sit on the Australian Plate, while the rest of the South Island sits on the Pacific. Because these plates are constantly shifting and grinding into each other, New Zealand gets a lot of geological action.

The southern tip of the Pacific Ring of Fire is presented by 3 active volcanoes: Mounts Ruapehu, Tongariro, and Ngauruhoe. The sacred Mounts of Ruapehu, Tongariro, and Ngauruhoe and their surrounding plateau are regarded as treasures so precious, that local Tuwharetoa Maori gifted them to the nation over a century ago. The resulting Tongariro National Park was the first National Park in the world created by gift from an indigenous people. All three volcanoes have erupted since European settlement, Ngauruhoe more than 70 times. Mount Ruapehu erupted in 1995 and 1996, throwing rocks, mud and ash high into the air. It caused some excitement, but it is not fear of fiery doom that most influences the national character. While most volcanic activity is now concentrated here in the north, ancient craters line the country all the way to the sub- Antarctic islands, 1,600 km south.

Lost Wonder The eruption of Mount Tarawera was the most dramatic volcanic event in recent New Zealand history. Erupting in the early hours of June 10th 1886, by 2.30am the mountain’s three peaks were blasting triple columns of smoke and ash thousands of metres into the sky. An hour later the bed of Lake Rotomahana blew out. Newspapers of the day recorded that sounds of the blast, volcanic lightning flashes and a glow in the night sky were registered as far south as Christchurch, 800 km away. In Auckland (230 km away), the flashing lights and what sounded like artillery fire sparked fears that a marauding battleship was attacking the city as part of a feared Russian invasion force. Many in the Manawatu believed that the visiting Russian man-of-war, Vestnick, was bombarding Wanganui. Three villages near Mount Tarawera were buried by the eruption. The death toll will never be known exactly; best estimates calculate around 150 people. At Te Wairoa, the villagers’ dwellings have now been dug out from beneath layers of ash, in places up to 10 metres deep. Wandering around village site today offers a fascinating insight into the fragility of life before the massive forces sometimes at work in this land. Lauded as ‘the eighth wonder of the world’, the Pink and White Terraces at Tarawera attracted visitors from around the world until they were destroyed by the eruption of Mount Tarawera in Formed by silica deposits, the beautiful steps sparked brilliantly as they descended the slopes beside Lake Rotomahana.

Moving around New Zealand, it comes as little surprise that Peter Jackson found the ideal setting for his ‘The Lord of the Ring’ trilogy. Throughout these islands, land and life has been shaped and woven together by volcanic activity. Although the South Island no longer has any active volcanoes, both main islands are dotted with volcanic vents and hot springs. Being straddled over two tectonic plates and sitting on the Pacific ‘ring of fire’,of course, has a lot of disadvantages. However, this subterranean activity also blesses New Zealand with some spectacular geothermal areas and relaxing hot springs, as well as providing electricity and heating in some areas.

Rotorua Rotorua is the centre of geothermal tourist activity, with plenty of mud pools, geysers, and hot springs in its active thermal areas. First settled by Maori who used the hot springs for cooking and bathing, Rotorua soon attracted European residents. The reputed health benefits of its hot pools quickly earned the area the name of ‘Cureland’. Rotorua sits squarely on the Pacific Ring of Fire, so volcanic activity is part of the city’s past and present. The city is also the tribal home of the Te Arawa people, who settled in lakeside geothermal areas more than 600 years ago. Entertaining in any weather, and at any time of the year, Rotorua promises to keep you captivated with geothermal phenomena and special cultural experiences. Rotorua also has a well-developed adventure culture – everything from sky diving to zorbing.

Healing properties believed to be so beneficial to human ailments proved to be less kind to buildings. After two years Rotorua’s original bath house collapsed, as did numerous other buildings added to the complex in subsequent years. But such was their popularity that rebuilding was never in doubt. The waters were regarded as soothing, relieving pain and reducing swelling in joints and tissues. The ‘Priest’s Bath’ was recommended for treating arthritis, rheumatism, and 'cases of nervous debility', as well as lumbago, sciatica and chronic dyspepsia. Sexual impotence could also be helped, and the Priest’s Bath was said to 'reduce the craving for alcohol'. Rotorua’s Bath House spa also helped pioneer modern practices of physiotherapy, with patients being encouraged to use swimming to exercise without bearing their weight on injured limbs. By the time of the First World War, the benefits of Rotorua's mineral pools were so highly regarded that convalescing soldiers were brought to the area to recover from war wounds. The Government Bath House is now a museum, but other spas have taken its place.

Pohutu Geyser in Rotorua The Pohutu Geyser is the most spectacular geyser at Rotorua’s Whakarewarewa Thermal Village. The geyser usually erupts every hour and shoots hot water around 20 metres high. Pohutu is Maori for ‘big splash’ or ‘explosion’.

Nature's Cure - Hot Springs Early European settlers came to appreciate New Zealand’s fiery soul as quickly as the Maori. In 1878 Father Mahoney, a Catholic Priest disabled with arthritis, is said to have been carried 88 km to Rotorua from Tauranga, to bathe in the acidic waters. After three months he was reputedly able to walk back to Tauranga. It was believed the close juxtaposition of strongly alkaline water alongside a still stronger acid, was the secret to the healing powers of the Rotorua springs. Whether it was the heat, the acidity, or the minerals in the water, the pool became known as the 'Priest's Bath' and Rotorua’s reputation as a health resort has been spreading ever since. In 1880 local Maori leaders signed an agreement setting aside Rotorua's thermal springs 'for the benefit of the people of the world'. The area’s first sanatorium opened in Water from nearby springs was piped to private bathrooms and larger douche massage rooms. There were also a number of deep pools. For over 100 years people from all over the world flocked to 'take the cure'. Crown Princess Louise of Sweden was among them, as were George Bernard Shaw and the Duke of Bedford. Many people still came back annually to this day.

Sunken Mountains Over thousands of years, the process of subduction has seen parts of the New Zealand landscape become submerged. The Marlborough Sounds and Fiordland are examples of high mountain ranges that have ‘sunk’ into the sea, creating spectacular sounds and fiords. These areas provide some of New Zealand most picturesque scenery, with steep lush hills plunging down to the deep still bays below. Clear, deep still water surrounded by beautiful bush makes these areas ideal for boating and kayaking

Cities' Volcanic Foundations Auckland, Christchurch, and Dunedin - three of the larger cities in this country are built on volcano fields. Auckland straddles the Auckland Volcanic Field, which has produced approximately 50 volcanoes. These take the form of cones, lakes, lagoons, islands, and several have produced extensive lava flows. Most of the cones have been partly or completely quarried away. The individual volcanoes are all considered extinct, although the volcanic field itself is merely dormant. Unlike the explosive subduction-driven volcanism in the central North Island, such as at Mount Ruapehu and Lake Taupo, Auckland's volcanoes are fueled entirely by basaltic magma. The most recent and by far the largest volcano, Rangitoto Island, was formed within the last 1000 years, and its eruptions destroyed the Māori settlements on neighbouring Motutapu Island some 700 years ago. Rangitoto's size, its symmetry, its position guarding the entrance to Waitemata Harbour and its visibility from many parts of the Auckland region make it Auckland's most iconic natural feature. Few birds and insects inhabit the island because of the rich acidic soil and the type of flora growing out of the rocky soil.

Rangitoto

Living With the Land Instead of fearing the forces still shaping the land, from the beginning, it seems the people of New Zealand have accepted them. Maori accepted them as the work of the god Ruamoko, in whose domain all geothermal activity belonged. In Maori mythology, far from being a threat, Ruapehu is a great mountain sent to quell the turbulence of the great 'fish' hauled from the sea by Maui to form the North Island. In another legend, the high priest, Ngatoroirangi (Nga-toro-i-rangi) was caught in a blizzard while climbing Mount Ngauruhoe. He prayed to his sisters in Hawaiki to send him fire to save him from freezing. The flames they sent south emerged first at White Island, then Rotorua and Taupo before finally bursting at Ngatoroirangi’s feet. Thus Ngatoroirangi is credited with bringing volcanic activity to Aotearoa New Zealand - not as a curse upon the land, but as a blessing. Such ancient myths place the volcano at the very centre of life in these islands. Across the broad centre of the North Island in particular, that notion is borne out by the way people live.

Life as Adventure It’s easy to see how this country produced an adventurer like New Zealander Sir Edmund Hillary, who conquered Everest. Scrambling up mountains was, and remains, just a normal thing New Zealanders do. Climbing the world’s highest mountain was only a logical extension. The Southern Alps run the length of the South Island, with several peaks over 10,000 feet. New Zealand's isolated volcanic landmass has no snakes, no bears and no mountain lions. The adventure experience is open to all. Even the violent forces that have torn and shaped the land from ancient times are generally so benign they offer temptation rather than terror. The volcanic peak of Mount Ruapehu is also one of New Zealand’s most popular ski resort. The volcano has one of only three crater lakes in the world surrounded by snow and ice. Every year hundreds of thousands of skiers take advantage of the only ski field in the world within 500 metres of an active volcanic crater. The ski field has a specially designed early warning system set to raise the alarm within 30 seconds of a significant increase of geothermal activity.