Five outstanding New Zealand sites have been designated and included in the list of 'The Second 100 IUGS Geological Heritage Sites'. The announcement was made by the President of The International Union of Geological Sciences (IUGS) at the 37th International Geological Congress in Busan, Republic of Korea. “This provides due recognition to some of New Zealand’s spectacular geological and landform features that make our country such a tourist mecca” said the New Zealand Geoscience Society’s Geoheritage spokesperson Dr Bruce Hayward. “It is even more amazing that New Zealand has the fourth most recognised sites of any countries after the United States (13), United Kingdom (7) and Italy (7).”

More than 700 experts from 80 nations and 16 international organisations participated in this global endeavour and selection of sites that cover the broad diversity of the world’s spectacular and significant geological features. “The New Zealand sites sit alongside such well-known features as the Giant’s Causeway in Northern Island, the Devil’s Tower in Wyoming, and the spectacular limestone pinnacles of Gulin, China,” says Hayward. A colourful coffee table book has been produced that summarises the significance of each listed site and can be downloaded from the web: https://iugs-geoheritage.org/publications/

The five listed New Zealand sites are:

Fjords and towering sea cliffs of Fiordland

Fiordland is recognised for its globally significant examples of spectacular fjords, deeply carved by glaciers through gneissic rocks uplifted high along the convergent boundary between the Pacific and Australian tectonic plates. There are 14 marine-flooded fjords, with 200-420 m-deep basins with shallow sills at their seaward mouths.

The glaciers cut deeply into hard crystalline plutonic and metamorphic rocks that were once buried to depths of 10-30 km. Glacial erosion of the uplifted Fiordland mountains has resulted in numerous sharp peaks rising from 1000 m in the south to 2700 m in the north. The west-flowing glaciers have carved classical straight, U-shaped valleys with spectacular glacially-striated vertical rock faces in the world’s highest sea cliffs, with numerous hanging tributary valleys and high waterfalls. Sediment on the floors of the fjords records their flooding by the sea as the glaciers melted and sea level rose, about 10-12,000 years ago after the end of the Last Ice Age. The glaciated landscape and fiords are the main reason for the recognition of Te Wahipounamu – Southwest New Zealand World Heritage Area.

Ruapehu Volcano

Ruapehu is recognised as an iconic and active stratovolcano, the typical volcano type produced along a convergent plate boundary. This stratovolcano is at the southern end of western arm of the Pacific Ring of Fire. It has been erupting at regular intervals over the past 200,000 years. The Ruapehu lavas are sourced from a magma chamber lying 5-10 km beneath the maunga. The lava chemistries have been studied in great detail providing a clear insight into the processes occurring at depth.

Also of world standard, have been studies on the periodic eruptions from the Crater Lake (Te Wai-ā-Moe) at the summit, and on the flow mechanisms of lahars flowing down the volcano from the hot lake. As a result, Ruapehu Volcano is an internationally recognised model of andesitic volcanism. Ruapehu is a major part of the Tongariro National Park World Heritage Area.

Rotorua’s geothermal fields (Ahi-Tupua)

Rotorua's geothermal fields (Ahi-Tupua) of Whakarewarewa, Waiotapu and Waimangu are included for their globally exemplary examples of diverse geothermal surface features, especially colourful sinter, geysers and boiling mud pools. The Rotorua fields now take their rightful place alongside Yellowstone (USA), Dallol (Ethiopia) and El Tatio (Chile) geothermal fields, which have also been listed.

Whakarewarewa has strong cultural values and has been used by the indigenous Māori for many centuries. It is best known for Te Puia sinter mound, with five geysers and sinter stalactites. Pohutu is the largest geyser in the Southern Hemisphere, erupting hourly and reaching heights of up to 30 m. Waiotapu is best known for its brightly coloured Champagne Pool and Artist's Palette sinter terrace, its numerous collapse craters and sulfur-lined fumaroles. It also has New Zealand's largest geothermal mud pool with numerous mud volcanoes. Waimangu Field is the world’s youngest geothermal field, created by the 1886 Tarawera eruption which destroyed the eighth wonder of the world - the Pink and White terraces. Growing here on the edge of Frying-Pan Lake are siliceous lily-pad stromatolites.

Muriwai megapillow lava flows

On the coast northwest of Auckland in Muriwai Regional Park is Muriwai megapillow lava flows. They include the world's largest, most complex and spectacular megapillow lava flow with internal feeding tubes having giant fans of cooling columns. These geological features are beautifully exposed in the sea cliffs south of Muriwai. They were erupted about 17 million years ago on the eastern submarine slopes of the giant Waitakere Volcano and have since been pushed up out of the sea. This extinct volcano has been largely eroded away by the pounding waves of the Tasman Sea.

Megapillow lava flows (with large pillow-shaped lava flow fingers) occur elsewhere (e.g. Iceland, Sardinia, Spain, Tasmania) but none match the cross-sectional exposure of the large Muriwai megapillow flow in terms of accessibility, size and complexity. Exposures of dikes feeding attached pillow lavas are only known elsewhere in Cyprus. The three-dimensional exposure of the smaller pillow lava flow with branching lobes and surface corrugations is on a par with a spectacular example in Oman.

Video: The world’s biggest pillow lavas.

https://www.youtube.com/watch?v=258E17Yh1BM

Maruia Falls

Maruia Falls, near Murchison, are of significance in the history of understanding the Earth’s structure. They were formed as a result of the powerful 1929 MS 7.8 Murchison Earthquake. The falls were exhumed by river erosion of gravels after its course was deviated by a landslip triggered by the earthquake. The Murchison Earthquake is renowned internationally in geophysical circles for its seismic P waves that were recorded in the core’s “shadow zone” in Greenland which led to the recognition of an inner and outer core in the Earth. Danish seismologist Inge Lehmann (1936) recognised a higher velocity of seismic waves from the Murchison Earthquake in an inner solid part of the Earth’s core surrounded by a liquid outer core.

© Scoop Media