100-512: Maungakiekie / One Tree Hill is a 182-metre (597 ft) volcanic peak and Tūpuna Maunga (ancestral mountain) in Auckland , New Zealand. It is an important place culturally and archeologically for both Māori and Pākehā . The suburb around the base of the hill is also called One Tree Hill . It is surrounded by the suburbs of Royal Oak to the west, and clockwise, Epsom , Greenlane , Oranga , and Onehunga . The summit provides views across
200-529: A ghost town ) and Fourpeaked Mountain in Alaska, which, before its September 2006 eruption, had not erupted since before 8000 BCE. John Logan Campbell Sir John Logan Campbell (3 November 1817 – 22 June 1912) was a Scottish-born New Zealand public figure . He was described by his contemporaries as "the father of Auckland ". John Logan Campbell was born in Edinburgh , Scotland, on 3 November 1817,
300-484: A magma chamber below the surface. The process that forms volcanoes is called volcanism . On Earth, volcanoes are most often found where tectonic plates are diverging or converging , and because most of Earth's plate boundaries are underwater, most volcanoes are found underwater. For example, a mid-ocean ridge , such as the Mid-Atlantic Ridge , has volcanoes caused by divergent tectonic plates whereas
400-637: A surgeon on the emigrant ship Palmyra . Confronted with drought and constrained prospects at the time Campbell departed Australia for New Zealand in March 1840 on the Lady Liford , arriving at Port Nicolson , and eventually travelling to Waiou (now called Whanganui Island ) on the Coromandel. Campbell and William Brown (a Scottish lawyer ) who had previously met in Adelaide, Australia, formed
500-526: A Tahuri ("The Plantations of Tahuri"), which were extensive kūmara (sweet potato) plantations managed by Tahuri, an agriculturalist and wife of Waiohua chief Te Ika-maupoho. Kiwi Tāmaki and most of the people of Maungakiekie / One Tree Hill did not live permanently at the mountain, instead migrating across circuits of the Auckland region collecting resources. Kiwi Tāmaki's rule and the Waiohua hegemony over
600-488: A Tītahi (the carvings of Tītahi). The tihi (summit) of the maunga was where the umbilical cord of Ngāti Awa rangatira Korokino was buried and a tōtara tree sprig was planted on top, giving rise to the name Te Tōtara-i-āhua ("The Tōtara That Stands Alone"), another common name for the mountain used by Tāmaki Māori . Maungakiekie / One Tree Hill is associated with the Waiohua confederation of tribes, who were active in
700-604: A bitter disappointment'. With this bereavement, Campbell said, 'we felt ourselves completely unhinged', 'the brightness of that Florence home was gone'. Apart from an interlude during 1860 and 1861, when he was obliged to go to Auckland to reinvigorate the firm – now called Brown Campbell and Company – and to install a resident partner, the Campbells lived in various parts of Europe until 1871. On his return early in 1871, Campbell took over full control. Two years later he bought out Brown's partnership share for over £40,000. Becoming
800-496: A business partnership after purchasing Motukorea from Te Kanini of Ngāti Tamaterā and the sub-chiefs Katikati and Ngatai with the aim of becoming merchant traders, in the rumoured new capital of New Zealand, Tāmaki Makaurau , soon to be named Auckland by Captain William Hobson following a gift of land and negotiations with Ngāti Whātua . They decided to abandon 'quill-driving and pill-making' and become traders in
900-437: A graduated spectrum, with much overlap between categories, and does not always fit neatly into only one of these three separate categories. The USGS defines a volcano as "erupting" whenever the ejection of magma from any point on the volcano is visible, including visible magma still contained within the walls of the summit crater. While there is no international consensus among volcanologists on how to define an active volcano,
1000-485: A hatch to service the aircraft warning light. The Stardome Observatory (previously known as Auckland Observatory ), is located within One Tree Hill Domain, and contains two telescopes and a planetarium . The observatory has, amongst other research, discovered and named the asteroid 19620 Auckland . Its current functions combine entertainment and education (via the planetarium and via public access to
1100-612: A lieutenant in the 1st Gloucestershire Regiment on 10 December 1889. The presentation of the park would probably have taken place after Campbell's death in the form of a bequest had not providence intervened in the form of the Royal Tour of 1901. In early 1901, Campbell was approached to be Mayor of Auckland for the royal visit by the Duke and Duchess of Cornwall in June that year. Aged 83 and long been in retirement, Campbell agreed on
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#17327729795371200-443: A paper was published suggesting a new definition for the word 'volcano' that includes processes such as cryovolcanism . It suggested that a volcano be defined as 'an opening on a planet or moon's surface from which magma , as defined for that body, and/or magmatic gas is erupted.' This article mainly covers volcanoes on Earth. See § Volcanoes on other celestial bodies and cryovolcano for more information. The word volcano
1300-778: A part of the business community again, he became involved with the Bank of New Zealand, the New Zealand Loan and Mercantile Agency Company, the New Zealand Insurance Company, and related companies. Campbell had a marked philanthropic interest in the advancement of education. He donated a sum of £500 and a block of land on the corner of Pitt and Wellington Streets and a brick school building was built there to house St Peter's School (a predecessor of St Peter's College, Auckland ). He founded Auckland's first school of art in 1878 and supported it for 11 years. He
1400-569: A son of the Edinburgh surgeon John Campbell and his wife Catherine and grandson of the 3rd baronet of Aberuchill and Kilbryde and Kilbryde castle near Dunblane , Perthshire. He had four sisters but his two elder brothers had died by the time he reached the age of two, and he became the only surviving son. Campbell graduated in medicine from the University of Edinburgh in 1839 and later that year sailed for Australia, New South Wales , as
1500-581: A suitable residence for his family. He envisaged an Italianate mansion similar to James Williamson 's at Hillsborough, surrounded by an elegant estate. He set about planting trees to create a suitable landscape garden. His wife Emma, however, had other ideas and the house, Killbryde, was eventually built in Parnell , a location much more handy to town. This property is now part of the Parnell Rose Gardens and Dove Myer Robinson Park . The house
1600-632: A volcano is largely determined by the composition of the lava it erupts. The viscosity (how fluid the lava is) and the amount of dissolved gas are the most important characteristics of magma, and both are largely determined by the amount of silica in the magma. Magma rich in silica is much more viscous than silica-poor magma, and silica-rich magma also tends to contain more dissolved gases. Lava can be broadly classified into four different compositions: Mafic lava flows show two varieties of surface texture: ʻAʻa (pronounced [ˈʔaʔa] ) and pāhoehoe ( [paːˈho.eˈho.e] ), both Hawaiian words. ʻAʻa
1700-555: A volcano is of a conical mountain, spewing lava and poisonous gases from a crater at its summit; however, this describes just one of the many types of volcano. The features of volcanoes are varied. The structure and behaviour of volcanoes depend on several factors. Some volcanoes have rugged peaks formed by lava domes rather than a summit crater while others have landscape features such as massive plateaus . Vents that issue volcanic material (including lava and ash ) and gases (mainly steam and magmatic gases) can develop anywhere on
1800-465: A volcano that has experienced one or more eruptions that produced over 1,000 cubic kilometres (240 cu mi) of volcanic deposits in a single explosive event. Such eruptions occur when a very large magma chamber full of gas-rich, silicic magma is emptied in a catastrophic caldera -forming eruption. Ash flow tuffs emplaced by such eruptions are the only volcanic product with volumes rivalling those of flood basalts . Supervolcano eruptions, while
1900-739: Is a volcanic field of over 60 cinder cones. Based on satellite images, it has been suggested that cinder cones might occur on other terrestrial bodies in the Solar system too; on the surface of Mars and the Moon. Stratovolcanoes (composite volcanoes) are tall conical mountains composed of lava flows and tephra in alternate layers, the strata that gives rise to the name. They are also known as composite volcanoes because they are created from multiple structures during different kinds of eruptions. Classic examples include Mount Fuji in Japan, Mayon Volcano in
2000-599: Is buried at in the English Cemetery at the Piazzale Donatello – Delgli Inglesi . 'And there lies buried in that little grave,' Campbell told his two daughters, 'the poor Papa's hopes that to him had been born a son who would be his pride and pleasure in his declining years and to whose care the name of his Firm would have been handed down to another generation. . . . And thus it is that our fondest hopes and dearest aspirations are ever and again doomed to
2100-554: Is buried on the summit of Maungakiekie One Tree Hill , adjacent to Cornwall Park. Auckland Grammar students formed part of the procession at Campbell’s funeral on 4 July 1912. He advised his closest advisors of his wish to erect a monument to demonstrate his love and regard for the Māori people and allocated funds for it in his will and Trust Deeds for the formation of his Residuary Estate to continue to distribute funds for charities for relief of poverty, advancement of education and support of
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#17327729795372200-412: Is characterized by a rough, clinkery surface and is the typical texture of cooler basalt lava flows. Pāhoehoe is characterized by its smooth and often ropey or wrinkly surface and is generally formed from more fluid lava flows. Pāhoehoe flows are sometimes observed to transition to ʻaʻa flows as they move away from the vent, but never the reverse. More silicic lava flows take the form of block lava, where
2300-565: Is derived from the name of Vulcano , a volcanic island in the Aeolian Islands of Italy whose name in turn comes from Vulcan , the god of fire in Roman mythology . The study of volcanoes is called volcanology , sometimes spelled vulcanology . According to the theory of plate tectonics, Earth's lithosphere , its rigid outer shell, is broken into sixteen larger and several smaller plates. These are in slow motion, due to convection in
2400-584: Is expressed using the volcanic explosivity index (VEI), which ranges from 0 for Hawaiian-type eruptions to 8 for supervolcanic eruptions. As of December 2022 , the Smithsonian Institution 's Global Volcanism Program database of volcanic eruptions in the Holocene Epoch (the last 11,700 years) lists 9,901 confirmed eruptions from 859 volcanoes. The database also lists 1,113 uncertain eruptions and 168 discredited eruptions for
2500-537: Is one of the several tuyas in the area of the Tuya River and Tuya Range in northern British Columbia. Tuya Butte was the first such landform analysed and so its name has entered the geological literature for this kind of volcanic formation. The Tuya Mountains Provincial Park was recently established to protect this unusual landscape, which lies north of Tuya Lake and south of the Jennings River near
2600-534: Is taken from Christopher Wren's grave at St Paul's Cathedral , London, the bronze plaque on the grave reads in Latin; '' Si monumentum requiris circumspice ," – translating to ''If you would seek my monument, look around you.'' In 1997, Campbell was posthumously inducted into the New Zealand Business Hall of Fame . The Sir John Logan Campbell Papers constitutes a record across almost all of
2700-507: Is the co-governance organisation established to administer the 14 Tūpuna Maunga . Auckland Council manages the Tūpuna Maunga under the direction of the TMA. On the summit of the hill is an obelisk , a memorial to Māori. Before the obelisk stands a bronze statue of a Māori warrior. The stone obelisk was designed by Richard Atkinson Abbot and completed in 1940, but the unveiling of the obelisk
2800-471: Is typically low in silica, shield volcanoes are more common in oceanic than continental settings. The Hawaiian volcanic chain is a series of shield cones, and they are common in Iceland , as well. Lava domes are built by slow eruptions of highly viscous lava. They are sometimes formed within the crater of a previous volcanic eruption, as in the case of Mount St. Helens , but can also form independently, as in
2900-514: The 2nd New Zealand Parliament , representing the electorates of the City of Auckland 1855–1856 (resigned). He was elected unopposed on 4 August 1860 in the Suburbs of Auckland electorate, replacing Joseph Hargreaves . Campbell retired at the end of the 2nd Parliament in late 1860. He was a minister without portfolio in the government of Edward Stafford between June and November 1856. Campbell
3000-478: The Auckland volcanic field , behind Rangitoto Island . The volcano erupted approximately 67,000 years ago. In pre-European times, Maungakiekie / One Tree Hill was the largest pā in the Tāmaki Makaurau region. The Māori name Maungakiekie means "mountain of the kiekie vine". The terraces of the pā were constructed by Ngāti Awa chief Tītahi in the 17th century, and were traditionally known as Ngā Whakairo
3100-617: The Cascade Volcanoes or the Japanese Archipelago , or the eastern islands of Indonesia . Hotspots are volcanic areas thought to be formed by mantle plumes , which are hypothesized to be columns of hot material rising from the core-mantle boundary. As with mid-ocean ridges, the rising mantle rock experiences decompression melting which generates large volumes of magma. Because tectonic plates move across mantle plumes, each volcano becomes inactive as it drifts off
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3200-626: The Hawaiian hotspot is an example. Volcanoes are usually not created where two tectonic plates slide past one another. Large eruptions can affect atmospheric temperature as ash and droplets of sulfuric acid obscure the Sun and cool Earth's troposphere . Historically, large volcanic eruptions have been followed by volcanic winters which have caused catastrophic famines. Other planets besides Earth have volcanoes. For example, volcanoes are very numerous on Venus. Mars has significant volcanoes. In 2009,
3300-834: The landform and may give rise to smaller cones such as Puʻu ʻŌʻō on a flank of Kīlauea in Hawaii. Volcanic craters are not always at the top of a mountain or hill and may be filled with lakes such as with Lake Taupō in New Zealand. Some volcanoes can be low-relief landform features, with the potential to be hard to recognize as such and be obscured by geological processes. Other types of volcano include cryovolcanoes (or ice volcanoes), particularly on some moons of Jupiter , Saturn , and Neptune ; and mud volcanoes , which are structures often not associated with known magmatic activity. Active mud volcanoes tend to involve temperatures much lower than those of igneous volcanoes except when
3400-420: The 17th and 18th centuries. The time of the third paramount chief of Waiohua, Kiwi Tāmaki , is associated with the time of the greatest unity and strength of the Waiohua confederation, when the Tāmaki Makaurau region was one of the most populated areas of Aotearoa. The cone and its surroundings are estimated to have been home to a population of up to 5,000. Kiwi Tāmaki , the third paramount chief of Waiohua, moved
3500-426: The Auckland area, and allows visitors to see both of Auckland's harbours. The scoria cones of the hill were erupted from three craters – one is intact and two have been breached by lava flows that rafted away part of the side of the scoria cone. Lava flows went in all directions, many towards Onehunga, covering an area of 20 square kilometres (7.7 sq mi), making it the second largest (in area covered) of
3600-588: The Henry's remaining land. Henry had referred to his property as Mt Prospect, however after the purchase Campbell renamed the farm the One Tree Hill Estate. Over the next 20 years, the farm was developed for cattle and sheep farming, and included potato cultivations. During this period, Campbell and Brown spent most of their time in Europe. In 1874, Campbell returned to Auckland and took sole ownership of
3700-587: The Near East, Scotland. There is also a section containing papers of his wife Lady Emma Campbell and daughter Winifred. Campbell’s gift of land and income attest to his efforts to secure and transform his farm estate into a public park gifted to the people of New Zealand in 1901. The collection includes the Cornwall Park Trust Board developments and management of this major city asset. The Sir John Logan Campbell Papers MS-51 are held at
3800-471: The Obelisk base and the bronze Warrior Statue. Campbell, like many European New Zealanders of his generation, had expected that Māori would gradually die out and that an impressive memorial would be a most fitting symbol to perpetuate their memory. By the 1930s this had obviously not happened, and some considered the term "memorial" was inappropriate with many Māori objecting to its use. During construction of
3900-581: The Onehunga area and to the reservoirs atop Maungawhau / Mount Eden . Cornwall Park, which adjoins the One Tree Hill Domain, was given by Sir John Logan Campbell to a private trust he had established to hold the land for the use of the public. In the 2014 Treaty of Waitangi settlement between the Crown and the Ngā Mana Whenua o Tāmaki Makaurau collective of 13 Auckland iwi and hapu (also known as
4000-883: The Pacific Ring of Fire has volcanoes caused by convergent tectonic plates. Volcanoes can also form where there is stretching and thinning of the crust's plates, such as in the East African Rift , the Wells Gray-Clearwater volcanic field , and the Rio Grande rift in North America. Volcanism away from plate boundaries has been postulated to arise from upwelling diapirs from the core–mantle boundary , 3,000 kilometres (1,900 mi) deep within Earth. This results in hotspot volcanism , of which
4100-622: The Philippines, and Mount Vesuvius and Stromboli in Italy. Ash produced by the explosive eruption of stratovolcanoes has historically posed the greatest volcanic hazard to civilizations. The lavas of stratovolcanoes are higher in silica, and therefore much more viscous, than lavas from shield volcanoes. High-silica lavas also tend to contain more dissolved gas. The combination is deadly, promoting explosive eruptions that produce great quantities of ash, as well as pyroclastic surges like
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4200-520: The Tāmaki Collective) and administered by the Tūpuna Maunga o Tāmaki Makaurau Authority (Tūpuna Maunga Authority). One Tree Hill Domain adjoins Cornwall Park 's 425 acres (172 ha), creating a total of 540 acres (220 hectares) of public green space. The hilltop is always accessible by foot, but because of anti-social behaviour, including drinking, vandalism and crime, after-dark road access to
4300-425: The Tāmaki Collective), ownership of the 14 Tūpuna Maunga of Tāmaki Makaurau / Auckland, was vested to the collective, including the volcano officially named Maungakiekie / One Tree Hill. The legislation specified that the land be held in trust "for the common benefit of Ngā Mana Whenua o Tāmaki Makaurau and the other people of Auckland". The Tūpuna Maunga o Tāmaki Makaurau Authority or Tūpuna Maunga Authority (TMA)
4400-618: The Tāmaki isthmus came to an end in the 1740s, after war with the Te Taoū hapū of Ngāti Whātua from South Kaipara . After the war, Te Taoū settled on the isthmus, and chief Tuperiri constructed a pā below the summit of Maungakiekie / One Tree Hill, known as Hikurangi. Hikurangi was abandoned around 1795 AD, with the death of Tuperiri, and Ngāti Whātua re-centred their activities around the Onehunga - Māngere area. While Maungakiekie / One Tree Hill
4500-613: The USGS defines a volcano as active whenever subterranean indicators, such as earthquake swarms , ground inflation, or unusually high levels of carbon dioxide or sulfur dioxide are present. The USGS defines a dormant volcano as any volcano that is not showing any signs of unrest such as earthquake swarms, ground swelling, or excessive noxious gas emissions, but which shows signs that it could yet become active again. Many dormant volcanoes have not erupted for thousands of years, but have still shown signs that they may be likely to erupt again in
4600-510: The boundary with the Yukon Territory . Mud volcanoes (mud domes) are formations created by geo-excreted liquids and gases, although several processes may cause such activity. The largest structures are 10 kilometres in diameter and reach 700 meters high. The material that is expelled in a volcanic eruption can be classified into three types: The concentrations of different volcanic gases can vary considerably from one volcano to
4700-402: The case of Lassen Peak . Like stratovolcanoes, they can produce violent, explosive eruptions, but the lava generally does not flow far from the originating vent. Cryptodomes are formed when viscous lava is forced upward causing the surface to bulge. The 1980 eruption of Mount St. Helens was an example; lava beneath the surface of the mountain created an upward bulge, which later collapsed down
4800-529: The cultural and medical interests he supported in his life time. The Trustees of his estate sought permission from Iwi throughout the Auckland Provincial region for his burial on the tihi summit and later for the building of the obelisk, which commenced in the 1930s to be complete by 1940 as a bicentennial project supported by the Government of the day. As it was completed during World War Two,
4900-800: The dividends as expatriates. Brown and his family left early in the year, but Campbell's departure was delayed. On 20 November 1856 he left the colony, he hoped for good. While travelling abroad, he married Emma Wilson on 25 February 1858 at Meerut , NWP India. She was a daughter of Sir John Cracroft Wilson , who later settled in Canterbury. They had four children: Cecily born in Auckland on 16 May 1861 died 20 November 1861 aged 6 months, Ida, born at Naples on 22 December 1859 and died in London 1880; and twins John Logan and Winifred born at Florence on 26 May 1864. John Logan died in infancy in Florence, Italy and
5000-799: The enormous area they cover, and subsequent concealment under vegetation and glacial deposits, supervolcanoes can be difficult to identify in the geologic record without careful geologic mapping . Known examples include Yellowstone Caldera in Yellowstone National Park and Valles Caldera in New Mexico (both western United States); Lake Taupō in New Zealand; Lake Toba in Sumatra , Indonesia; and Ngorongoro Crater in Tanzania. Volcanoes that, though large, are not large enough to be called supervolcanoes, may also form calderas in
5100-431: The flow is covered with angular, vesicle-poor blocks. Rhyolitic flows typically consist largely of obsidian . Tephra is made when magma inside the volcano is blown apart by the rapid expansion of hot volcanic gases. Magma commonly explodes as the gas dissolved in it comes out of solution as the pressure decreases when it flows to the surface . These violent explosions produce particles of material that can then fly from
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#17327729795375200-622: The following year by Auckland Council due to the risk of it falling. In 2007, the chainsaw used by activist Mike Smith in the first attack was placed on sale on auction site TradeMe , but withdrawn by the website after complaints and a poll of users. It was later listed on eBay . The chainsaw is now in the collection of Museum of New Zealand Te Papa Tongarewa . A dawn ceremony conducted by the Tūpuna Maunga Authority took place upon Maungakiekie / One Tree Hill on 11 June 2016 planting nine young tōtara and pōhutukawa grown from parent trees on
5300-610: The formation of a submarine volcano off the coast of Mayotte . Subglacial volcanoes develop underneath ice caps . They are made up of lava plateaus capping extensive pillow lavas and palagonite . These volcanoes are also called table mountains, tuyas , or (in Iceland) mobergs. Very good examples of this type of volcano can be seen in Iceland and in British Columbia . The origin of the term comes from Tuya Butte , which
5400-585: The future. In an article justifying the re-classification of Alaska's Mount Edgecumbe volcano from "dormant" to "active", volcanologists at the Alaska Volcano Observatory pointed out that the term "dormant" in reference to volcanoes has been deprecated over the past few decades and that "[t]he term "dormant volcano" is so little used and undefined in modern volcanology that the Encyclopedia of Volcanoes (2000) does not contain it in
5500-466: The glossaries or index", however the USGS still widely employs the term. Previously a volcano was often considered to be extinct if there were no written records of its activity. Such a generalization is inconsistent with observation and deeper study, as has occurred recently with the unexpected eruption of the Chaitén volcano in 2008. Modern volcanic activity monitoring techniques, and improvements in
5600-783: The infant city of Auckland. Campbell quickly became prominent in Auckland, both in business circles and in public life. He was a director of the Bank of New Zealand , the New Zealand Loan and Mercantile Agency Company , and the New Zealand Insurance Company . Campbell was elected to the Auckland Provincial Council on 20 March 1855, and he served until 15 September of that year. He was then Superintendent of Auckland Province from 25 November 1855 to 17 September 1856. Campbell entered
5700-492: The interior of a continent and lead to rifting. Early stages of rifting are characterized by flood basalts and may progress to the point where a tectonic plate is completely split. A divergent plate boundary then develops between the two halves of the split plate. However, rifting often fails to completely split the continental lithosphere (such as in an aulacogen ), and failed rifts are characterized by volcanoes that erupt unusual alkali lava or carbonatites . Examples include
5800-503: The maunga. The strongest single tree will eventually remain and kiekie will be added. In 2021, The Spinoff produced a short documentary centred around the chainsaw called "The chainsaw used on One Tree Hill and heard across Aotearoa". [REDACTED] Media related to Maungakiekie / One Tree Hill at Wikimedia Commons Volcano A volcano is a rupture in the crust of a planetary-mass object , such as Earth , that allows hot lava , volcanic ash , and gases to escape from
5900-419: The mid-oceanic ridge is above sea level, volcanic islands are formed, such as Iceland . Subduction zones are places where two plates, usually an oceanic plate and a continental plate, collide. The oceanic plate subducts (dives beneath the continental plate), forming a deep ocean trench just offshore. In a process called flux melting , water released from the subducting plate lowers the melting temperature of
6000-551: The modelling of the factors that produce eruptions, have helped the understanding of why volcanoes may remain dormant for a long time, and then become unexpectedly active again. The potential for eruptions, and their style, depend mainly upon the state of the magma storage system under the volcano, the eruption trigger mechanism and its timescale. For example, the Yellowstone volcano has a repose/recharge period of around 700,000 years, and Toba of around 380,000 years. Vesuvius
6100-415: The most dangerous type, are very rare; four are known from the last million years , and about 60 historical VEI 8 eruptions have been identified in the geologic record over millions of years. A supervolcano can produce devastation on a continental scale, and severely cool global temperatures for many years after the eruption due to the huge volumes of sulfur and ash released into the atmosphere. Because of
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#17327729795376200-438: The mud volcano is actually a vent of an igneous volcano. Volcanic fissure vents are flat, linear fractures through which lava emerges. Shield volcanoes, so named for their broad, shield-like profiles, are formed by the eruption of low-viscosity lava that can flow a great distance from a vent. They generally do not explode catastrophically but are characterized by relatively gentle effusive eruptions . Since low-viscosity magma
6300-413: The new capital, Auckland. On 21 December 1840 they began operations as Auckland's first merchant firm, Brown and Campbell, when Campbell pitched his tent on the edge of the small bay, at the foot of present day Queen Street . Campbell and Brown built Acacia Cottage in 1841, on their street frontage the partners put up a two-storeyed warehouse from which they conducted their business as general merchants in
6400-452: The next. Water vapour is typically the most abundant volcanic gas, followed by carbon dioxide and sulfur dioxide . Other principal volcanic gases include hydrogen sulfide , hydrogen chloride , and hydrogen fluoride . A large number of minor and trace gases are also found in volcanic emissions, for example hydrogen , carbon monoxide , halocarbons , organic compounds, and volatile metal chlorides. The form and style of an eruption of
6500-531: The nineteenth century. John Logan Campbell’s personal papers and those of his business enterprises reflect both business and social history from the 1840s to 1910. The collection is fundamental to research into the earliest origins of Auckland’s European settlement and the development of the provincial economy. The papers record a range of activities, events and business across the Auckland Province, also include "Reminiscences" of his time in Europe, India,
6600-876: The north side of the mountain. Cinder cones result from eruptions of mostly small pieces of scoria and pyroclastics (both resemble cinders, hence the name of this volcano type) that build up around the vent. These can be relatively short-lived eruptions that produce a cone-shaped hill perhaps 30 to 400 metres (100 to 1,300 ft) high. Most cinder cones erupt only once and some may be found in monogenetic volcanic fields that may include other features that form when magma comes into contact with water such as maar explosion craters and tuff rings . Cinder cones may form as flank vents on larger volcanoes, or occur on their own. Parícutin in Mexico and Sunset Crater in Arizona are examples of cinder cones. In New Mexico , Caja del Rio
6700-456: The obelisk, a suggestion was made that it should be described as a centennial tower to mark the centennial year of the signing of the Treaty of Waitangi and not a memorial. A locked door is built into the eastern plaque at the base of the obelisk. This gives access to a small room from which a vertical ladder leads up inside the column itself. At the top is a small window looking to the north and
6800-549: The ocean surface as new islands or floating pumice rafts . In May and June 2018, a multitude of seismic signals were detected by earthquake monitoring agencies all over the world. They took the form of unusual humming sounds, and some of the signals detected in November of that year had a duration of up to 20 minutes. An oceanographic research campaign in May 2019 showed that the previously mysterious humming noises were caused by
6900-420: The ocean surface, due to the rapid cooling effect and increased buoyancy in water (as compared to air), which often causes volcanic vents to form steep pillars on the ocean floor. Hydrothermal vents are common near these volcanoes, and some support peculiar ecosystems based on chemotrophs feeding on dissolved minerals. Over time, the formations created by submarine volcanoes may become so large that they break
7000-471: The ocean's surface. In the deep ocean basins, the tremendous weight of the water prevents the explosive release of steam and gases; however, submarine eruptions can be detected by hydrophones and by the discoloration of water because of volcanic gases . Pillow lava is a common eruptive product of submarine volcanoes and is characterized by thick sequences of discontinuous pillow-shaped masses which form underwater. Even large submarine eruptions may not disturb
7100-401: The official dedication was delayed as the Maori elders did not wish to formally dedicate it during a time of bloodshed in line with tikanga. Sir John Logan Campbell's grave is located in the middle of the flat platform which is part of a structure supporting the obelisk complex, built of local volcanic basalt, which serves as the forecourt to the monument. The epithet for Sir John Logan Campbell
7200-431: The older telescope) as well as ongoing research with both telescopes. It is operated by a charitable trust. During the Waiohua confederation of the 17th and 18th century, the summit of the maunga was known for its single tōtara tree. When Auckland was founded as a colonial town a tree stood near the tihi which gave the maunga its English name. Two accounts identify it as a pōhutukawa ( Metrosideros excelsa ). This tree
7300-468: The one that destroyed the city of Saint-Pierre in Martinique in 1902. They are also steeper than shield volcanoes, with slopes of 30–35° compared to slopes of generally 5–10°, and their loose tephra are material for dangerous lahars . Large pieces of tephra are called volcanic bombs . Big bombs can measure more than 1.2 metres (4 ft) across and weigh several tons. A supervolcano is defined as
7400-425: The overlying mantle wedge, thus creating magma . This magma tends to be extremely viscous because of its high silica content, so it often does not reach the surface but cools and solidifies at depth . When it does reach the surface, however, a volcano is formed. Thus subduction zones are bordered by chains of volcanoes called volcanic arcs . Typical examples are the volcanoes in the Pacific Ring of Fire , such as
7500-423: The park's borders. Because One Tree Hill Domain is high and relatively central, the city has long used it for its potable water reservoirs. The first of these was constructed in 1900 atop the western peak; though it is no longer in service, the small structure remains in place. Five further reservoirs were subsequently built underground, with the latest completed in 1977. They are currently used to maintain supply to
7600-619: The plume, and new volcanoes are created where the plate advances over the plume. The Hawaiian Islands are thought to have been formed in such a manner, as has the Snake River Plain , with the Yellowstone Caldera being part of the North American plate currently above the Yellowstone hotspot . However, the mantle plume hypothesis has been questioned. Sustained upwelling of hot mantle rock can develop under
7700-422: The property, planning to build an Italian-style mansion adjacent to the mountain. Campbell's wife Emma did not approve of the designs or location, so by 1876 abandoned plans for the villa. In 1878, he planted an olive grove at Maungakiekie / One Tree Hill, the only commercial olive grove in New Zealand until the 1980s. In 1880, after the death of his daughter Ida, Campbell decided to gift the One Tree Hill Estate to
7800-585: The proviso that he would fulfil representative functions only and step down after the visit, with a deputy undertaken most of the mayoral tasks. In the April 1901 mayoral election , he received nearly 80% of the votes. During the royal visit, Logan Campbell donated Cornwall Park to the people of New Zealand and named it after the Duke and Duchess. Campbell resigned in July and the city councillors voted Alfred Kidd into
7900-465: The public, leasing the land to Chinese market gardener Fong Ming Quong in the mean-time. In 1901, Campbell formally handed over the land to the public during the visit of the Duke and Duchess of Cornwall in 1901 (who later became King George V and Queen Mary of Teck ). One Tree Hill Domain, a 118-acre (48 ha) park, is owned by the Ngā Mana Whenua o Tāmaki Makaurau Collective (also known as
8000-540: The role; Kidd had acted in support of Campbell and taken on many of the mayoral tasks. Campbell was made a knight bachelor on 14 August 1902, after the honour had been announced in the 1902 Coronation Honours list published on 26 June 1902. He lived long enough to witness the erection of the bronze statue of him in Mayoral Robes at the Manukau Road entrance to Cornwall Park. He died on 22 June 1912, and
8100-435: The same time interval. Volcanoes vary greatly in their level of activity, with individual volcanic systems having an eruption recurrence ranging from several times a year to once in tens of thousands of years. Volcanoes are informally described as erupting , active , dormant , or extinct , but the definitions of these terms are not entirely uniform among volcanologists. The level of activity of most volcanoes falls upon
8200-492: The same way; they are often described as "caldera volcanoes". Submarine volcanoes are common features of the ocean floor. Volcanic activity during the Holocene Epoch has been documented at only 119 submarine volcanoes, but there may be more than one million geologically young submarine volcanoes on the ocean floor. In shallow water, active volcanoes disclose their presence by blasting steam and rocky debris high above
8300-622: The seat of power of the confederation from Maungawhau / Mount Eden to Maungakiekie / One Tree Hill. Near the summit of Maungakiekie / One Tree Hill was a gigantic pahū pounamu (greenstone gong) known as Whakarewa-tāhuna ("Lifted from the Banks of the Sea"), which Kiwi Tāmaki used to call for the warriors of the Tāmaki isthmus to assemble. During the later Waiohua period, the southern slopes of Maungakiekie / One Tree Hill south to Onehunga were known as Nga Māra
8400-622: The solidified erupted material that makes up the mantle of a volcano may be stripped away that its inner anatomy becomes apparent. Using the metaphor of biological anatomy , such a process is called "dissection". Cinder Hill , a feature of Mount Bird on Ross Island , Antarctica , is a prominent example of a dissected volcano. Volcanoes that were, on a geological timescale, recently active, such as for example Mount Kaimon in southern Kyūshū , Japan , tend to be undissected. Eruption styles are broadly divided into magmatic, phreatomagmatic, and phreatic eruptions. The intensity of explosive volcanism
8500-399: The summit was closed in 2008. Due to the spiritual and cultural significance of Maungakiekie / One Tree Hill to Māori, and for pedestrian safety, the summit road was permanently closed to most vehicles in March 2019. The area contains two parks, One Tree Hill Domain and Cornwall Park, which are next to each other and thus often perceived as one. One Tree Hill Domain is open to the public and
8600-406: The surrounding areas, and initially not seismically monitored before its unanticipated and catastrophic eruption of 1991. Two other examples of volcanoes that were once thought to be extinct, before springing back into eruptive activity were the long-dormant Soufrière Hills volcano on the island of Montserrat , thought to be extinct until activity resumed in 1995 (turning its capital Plymouth into
8700-434: The theory of plate tectonics. For example, some volcanoes are polygenetic with more than one period of activity during their history; other volcanoes that become extinct after erupting exactly once are monogenetic (meaning "one life") and such volcanoes are often grouped together in a geographical region. At the mid-ocean ridges , two tectonic plates diverge from one another as hot mantle rock creeps upwards beneath
8800-444: The thinned oceanic crust . The decrease of pressure in the rising mantle rock leads to adiabatic expansion and the partial melting of the rock, causing volcanism and creating new oceanic crust. Most divergent plate boundaries are at the bottom of the oceans, and so most volcanic activity on Earth is submarine, forming new seafloor . Black smokers (also known as deep sea vents) are evidence of this kind of volcanic activity. Where
8900-459: The two was felled in another attack. The remaining tree was later attacked twice with chainsaws by Māori activists to draw attention to injustices they claimed the New Zealand government had inflicted upon Māori. The first attack happened on 28 October 1994, the anniversary of the 1835 Declaration of Independence. A second attack in October 2000 left the tree unable to recover, and it was removed
9000-431: The underlying ductile mantle , and most volcanic activity on Earth takes place along plate boundaries, where plates are converging (and lithosphere is being destroyed) or are diverging (and new lithosphere is being created). During the development of geological theory, certain concepts that allowed the grouping of volcanoes in time, place, structure and composition have developed that ultimately have had to be explained in
9100-492: The volcano. Solid particles smaller than 2 mm in diameter ( sand-sized or smaller) are called volcanic ash. Tephra and other volcaniclastics (shattered volcanic material) make up more of the volume of many volcanoes than do lava flows. Volcaniclastics may have contributed as much as a third of all sedimentation in the geologic record. The production of large volumes of tephra is characteristic of explosive volcanism. Through natural processes, mainly erosion , so much of
9200-424: The volcanoes of the East African Rift . A volcano needs a reservoir of molten magma (e.g. a magma chamber), a conduit to allow magma to rise through the crust, and a vent to allow the magma to escape above the surface as lava. The erupted volcanic material (lava and tephra) that is deposited around the vent is known as a volcanic edifice , typically a volcanic cone or mountain. The most common perception of
9300-529: Was a founder of Auckland Grammar School having become the third chairman of the school in 1879. . When depression overwhelmed Auckland in 1885 and the Stock Market collapsed in 1886, there began a desperate struggle for financial survival. Campbell sold several businesses and properties, concentrating his energies on Brown Campbell and Company, a brewery and liquor importer. Campbell retained his properties at One Tree Hill partly because he wanted to create
9400-543: Was a successful businessman and had entered into a partnership with William Brown in 1840, beginning operations as Auckland's first merchant firm, Brown and Campbell. In May 1854, the Signet ship was purchased on behalf of Campbell in Geelong, Australia for the timber trade. By 1856 Campbell and Brown decided that their enterprises and properties, now worth £110,000, could be entrusted to a salaried manager, while they lived on
9500-434: Was cut down by a Pākehā settler in 1852, in an act of vandalism in one account, or for firewood in another. An exotic Monterey pine was planted in 1875 by John Logan Campbell to replace the tōtara or pōhutukawa. Campbell repeatedly tried to grow native trees on the tihi, but the trees failed to survive – with only two pines, originally part of a shelter belt for the native trees, surviving for long. However, in 1960, one of
9600-405: Was delayed until after World War II on 24 April 1948. This was in keeping with Māori custom of not holding such ceremonies during a time of bloodshed. Beneath it is the grave of Sir John Logan Campbell who bequeathed £5,000 for the obelisk. His grave is a plain granite slab, ornamented only by a bronze wreath. It lies in the middle of the viewing platform, on axis with the main memorial plaques on
9700-410: Was demolished in 1924. In his later years, Campbell was concerned about the increasing suburban development of Auckland and decided to donate his remaining farmland at One Tree Hill to the city as a public amenity to be called Corinth Park – named after a part of Greece which Campbell had admired on his travels. Winifred the only surviving child of John and Emma Campbell married Herbert Cyril Orde Murray
9800-421: Was described by Roman writers as having been covered with gardens and vineyards before its unexpected eruption of 79 CE , which destroyed the towns of Herculaneum and Pompeii . Accordingly, it can sometimes be difficult to distinguish between an extinct volcano and a dormant (inactive) one. Long volcano dormancy is known to decrease awareness. Pinatubo was an inconspicuous volcano, unknown to most people in
9900-417: Was formerly administered by Auckland City Council but since 2012 has been owned and administered by the Tūpuna Maunga Authority. All decisions are made by the owners, who have delegated minor day-to-day operations to Cornwall Park Trust. Cornwall Park is a private park, also open to the public, administered by the Cornwall Park Trust Board. The Trust's endowment includes income from leasehold properties adjoining
10000-481: Was no longer central to Ngāti Whātua life, it remained a central part of the iwi's rohe . In 1844, Ngāti Whātua chiefs sold a block of land which included Maungakiekie / One Tree Hill to a merchant, Thomas Henry. Most of this property was removed from Henry's ownership in 1847, with the 115 acres of the hill and surrounding land becoming a Crown reserve, now known as the One Tree Hill Domain. In 1853, Auckland businessmen John Logan Campbell and William Brown purchased
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