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Oruanui Eruption
The Oruanui eruption of New Zealand's Taupō Volcano (also known as the Kawakawa eruption or Kawakawa/Oruanui event) was the world's most recent Supervolcano#Known supereruptions, supereruption.} Eruption With a Volcanic Explosivity Index of 8, it is one of the largest eruptions ever to occur in New Zealand. It occurred about 26,500 years ago in the Late Pleistocene and generated approximately of pyroclastic fall deposits, of pyroclastic density current (PDC) deposits (mostly ignimbrite) and of primary intracaldera material, equivalent to of magma, totaling of total deposits. The eruption is divided into 10 different phases on the basis of nine geological map, mappable fall strata, units and a tenth, poorly preserved but volumetrically dominant fall unit. Modern-day Lake Taupō, in area and deep, partly fills the caldera generated during this eruption. A structural collapse is concealed beneath Lake Taupō, while the lake outline at least partly reflects volcano-tectonic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Taupō Volcano
Lake Taupō, in the centre of New Zealand's North Island, is the caldera of the Taupō Volcano, a large rhyolitic supervolcano. This huge volcano has produced two of the world's most violent eruptions in geologically recent times. ImageSize = width:320 height:800 PlotArea = right:50 top:10 left:50 bottom:10 DateFormat = yyyy TimeAxis = orientation:vertical order:reverse Period = from:-10000 till:2050 AlignBars = early ScaleMajor = unit:year increment:1000 start:-10000 Colors = id:canvas value:rgb(1,1,0.85) BackgroundColors = canvas:canvas PlotData = width:15 color:white bar:test from:-10000 till:1200 # Pre Maori PlotData = width:15 color:yellow bar:test from:1200 till:1840 # Pre accurate PlotData = width:15 color:orange bar:test from:1840 till:2050 # Accurate PlotData = at:-9999 shift:(30,0) text: Recent eruptions of Taupō caldera at:-9999 shift:(200,0) textcolor:red text: Eruptive at:-9850 shift:(80,-1) textcolor:red fontsize:S text:(Er ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Breccia
Breccia () is a rock composed of large angular broken fragments of minerals or rocks cemented together by a fine-grained matrix. The word has its origins in the Italian language, in which it means "rubble". A breccia may have a variety of different origins, as indicated by the named types including sedimentary breccia, tectonic breccia, igneous breccia, impact breccia, and hydrothermal breccia. A megabreccia is a breccia composed of very large rock fragments, sometimes kilometers across, which can be formed by landslides, impact events, or caldera collapse. Types Breccia is composed of coarse rock fragments held together by cement or a fine-grained matrix. Like conglomerate, breccia contains at least 30 percent of gravel-sized particles (particles over 2mm in size), but it is distinguished from conglomerate because the rock fragments have sharp edges that have not been worn down. These indicate that the gravel was deposited very close to its source area, since otherwise th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Catchment
A drainage basin is an area of land where all flowing surface water converges to a single point, such as a river mouth, or flows into another body of water, such as a lake or ocean. A basin is separated from adjacent basins by a perimeter, the ''drainage divide'', made up of a succession of elevated features, such as ridges and hills. A basin may consist of smaller basins that merge at river confluences, forming a hierarchical pattern. Other terms for a drainage basin are catchment area, catchment basin, drainage area, river basin, water basin, and impluvium. In North America, they are commonly called a watershed, though in other English-speaking places, "watershed" is used only in its original sense, that of a drainage divide. In a closed drainage basin, or endorheic basin, the water converges to a single point inside the basin, known as a sink, which may be a permanent lake, a dry lake, or a point where surface water is lost underground. Drainage basins are similar but no ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mangakino
Mangakino is a small town on the banks of the Waikato River in the North Island of New Zealand. It is located close to the hydroelectric power station at Lake Maraetai, southeast of Hamilton. The town and its infrastructure are administered as the Mangakino Pouakani ward by the Taupō District Council. History and culture In 1896, (after 40 years of resistance) the British Crown acquired the Wairarapa Lakes from Ngāti Kahungunu and in 1915, gave in return land in middle North Island, land known as part of the Pouakani Block. At that time the land where Mangakino lies today was described as native bush and pumice wastelands, barren, unoccupied and unfarmed. In 1946, as the Karapiro Dam neared completion, workers were to transfer to the next dam construction site – 'Maraetai I', near Mangakino. The Crown, under the Public Works Act, reacquired a portion of the unoccupied Pouakani Block alongside the Waikato River to build a "hydroelectric station" and a temporary township, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Terrace (geology)
In geology, a terrace is a step-like landform. A terrace consists of a flat or gently sloping geomorphic surface, called a tread, that is typically bounded on one side by a steeper ascending slope, which is called a "riser" or "scarp". The tread and the steeper descending slope (riser or scarp) together constitute the terrace. Terraces can also consist of a tread bounded on all sides by a descending riser or scarp. A narrow terrace is often called a bench.Howard, A.D., R.W. Fairbridge, J.H. Quinn, 1968, "Terraces, Fluvial—Introduction", in R.W. Fairbridge, ed., ''The Encyclopedia of Geomorphology: Encyclopedia of Earth Science Series'', vol. 3. Reinhold Book Corporation. New York, New York.Jackson, J.A., 1997, ''Glossary of Geology''. American Geological Institute. Alexandria, Virginia. The sediments underlying the tread and riser of a terrace are also commonly, but incorrectly, called terraces, leading to confusion. Terraces are formed in various ways. Fluvial terraces ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tasman Sea
The Tasman Sea (Māori: ''Te Tai-o-Rēhua'', ) is a marginal sea of the South Pacific Ocean, situated between Australia and New Zealand. It measures about across and about from north to south. The sea was named after the Dutch explorer Abel Janszoon Tasman, who in 1642 was the first known person to cross it. British explorer Lieutenant James Cook later extensively navigated the Tasman Sea in the 1770s during his three voyages of exploration. The Tasman Sea is informally referred to in both Australian and New Zealand English as the Ditch; for example, "crossing the Ditch" means travelling to Australia from New Zealand, or vice versa. The diminutive term "the Ditch" used for the Tasman Sea is comparable to referring to the North Atlantic Ocean as "the Pond". Climate The south of the sea is passed over by depressions going from west to east. The northern limit of these westerly winds is near to 40°S. During the southern winter, from April to October, the northern branch ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hauraki Plains
The Hauraki Plains are a geographical feature and non-administrative area (though Hauraki Plains County Council existed from 1920 to 1989 and a statistical Area Unit remains) located in the northern North Island of New Zealand, at the lower (northern) end of the Thames Valley. They are located 75 kilometres south-east of Auckland, at the foot of the Coromandel Peninsula and occupy the southern portion of a rift valley bounded on the north-west by the Hunua Ranges, to the east by the Coromandel and Kaimai ranges and the west by a series of undulating hills which separate the plains from the much larger plains of the Waikato River. Broadly, the northern and southern parts of the Hauraki Plains are administered by the Hauraki District and the Matamata-Piako District respectively. The alluvial plains have been built up by sediment deposited by the Piako and Waihou rivers, which flow north to reach the sea at the Firth of Thames, and earlier by the ancestral Waikato River. The r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Waikato River
The Waikato River is the longest river in New Zealand, running for through the North Island. It rises on the eastern slopes of Mount Ruapehu, joining the Tongariro River system and flowing through Lake Taupō, New Zealand's largest lake. It then drains Taupō at the lake's northeastern edge, creates the Huka Falls, and flows northwest through the Waikato Plains. It empties into the Tasman Sea south of Auckland, at Port Waikato. It gives its name to the Waikato region that surrounds the Waikato Plains. The present course of the river was largely formed about 17,000 years ago. Contributing factors were climate warming, forest being reestablished in the river headwaters and the deepening, rather than widening, of the existing river channel. The channel was gradually eroded as far up river as Piarere, leaving the old Hinuera channel through the Hinuera Gap high and dry. The remains of the old course are seen clearly at Hinuera, where the cliffs mark the ancient river edges. The Wai ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
South Island
The South Island, also officially named , is the larger of the two major islands of New Zealand in surface area, the other being the smaller but more populous North Island. It is bordered to the north by Cook Strait, to the west by the Tasman Sea, and to the south and east by the Pacific Ocean. The South Island covers , making it the world's 12th-largest island. At low altitude, it has an oceanic climate. The South Island is shaped by the Southern Alps which run along it from north to south. They include New Zealand's highest peak, Aoraki / Mount Cook at . The high Kaikōura Ranges lie to the northeast. The east side of the island is home to the Canterbury Plains while the West Coast is famous for its rough coastlines such as Fiordland, a very high proportion of native bush and national parks, and the Fox and Franz Josef Glaciers. The main centres are Christchurch and Dunedin. The economy relies on agriculture and fishing, tourism, and general manufacturing and services. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chatham Islands
The Chatham Islands ( ) (Moriori: ''Rēkohu'', 'Misty Sun'; mi, Wharekauri) are an archipelago in the Pacific Ocean about east of New Zealand's South Island. They are administered as part of New Zealand. The archipelago consists of about ten islands within an approximate radius, the largest of which are Chatham Island and Pitt Island (Rangiauria). They include New Zealand's easternmost point, the Forty-Fours. Some of the islands, formerly cleared for farming, are now preserved as nature reserves to conserve some of the unique flora and fauna. The islands were uninhabited when the Moriori people arrived around 1500 CE and developed a peaceful way of life. In 1835 members of the Ngāti Mutunga and Ngāti Tama Māori iwi from the North Island of New Zealand invaded the islands and nearly exterminated the Moriori, enslaving the survivors. Later during the period of European colonisation of New Zealand, the New Zealand Company claimed that the British Crown had never include ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volcanic Ash
Volcanic ash consists of fragments of rock, mineral crystals, and volcanic glass, created during volcano, volcanic eruptions and measuring less than 2 mm (0.079 inches) in diameter. The term volcanic ash is also often loosely used to refer to all explosive eruption products (correctly referred to as ''tephra''), including particles larger than 2 mm. Volcanic ash is formed during explosive volcanic eruptions when dissolved gases in magma expand and escape violently into the atmosphere. The force of the gases shatters the magma and propels it into the atmosphere where it solidifies into fragments of volcanic rock and glass. Ash is also produced when magma comes into contact with water during phreatomagmatic eruptions, causing the water to explosively flash to steam leading to shattering of magma. Once in the air, ash is transported by wind up to thousands of kilometres away. Due to its wide dispersal, ash can have a number of impacts on society, including animal a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tephra
Tephra is fragmental material produced by a volcanic eruption regardless of composition, fragment size, or emplacement mechanism. Volcanologists also refer to airborne fragments as pyroclasts. Once clasts have fallen to the ground, they remain as tephra unless hot enough to fuse into pyroclastic rock or tuff. Tephrochronology is a geochronological technique that uses discrete layers of tephra—volcanic ash from a single eruption—to create a chronological framework in which paleoenvironmental or archaeological records can be placed. When a volcano explodes, it releases a variety of tephra including ash, cinders, and blocks. These layers settle on the land and, over time, sedimentation occurs incorporating these tephra layers into the geologic record. Often, when a volcano explodes, biological organisms are killed and their remains are buried within the tephra layer. These fossils are later dated by scientists to determine the age of the fossil and its place within the geolo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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