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Kaikohe Hill
Kaikohe Hill (also Tokareireia) is a 282 m high basaltic scoria cone in the Kaikohe-Bay of Islands volcanic field in New Zealand. It is on the western edge of the town of Kaikohe Kaikohe is the seat of the Far North District of New Zealand, situated on State Highway 12 about 260 km from Auckland. It is the largest inland town and highest community above sea level in the Northland Region. With a population of over .... References Geological Society of New Zealand External links View from near the Hone Heke Memorial, on Kaikohe Hill. Far North District Volcanoes of the Northland Region Kaikohe {{Northland-geo-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kaikohe
Kaikohe is the seat of the Far North District of New Zealand, situated on State Highway 12 about 260 km from Auckland. It is the largest inland town and highest community above sea level in the Northland Region. With a population of over 4000 people it is a shopping and service centre for an extensive farming district and is sometimes referred to as "the hub of the north". Geography The town is situated on a relatively level site surrounded mainly by undulating plains and is nearby many former pā sites including Nga Huha, Pouerua, Te Rua-hoanga, Ngaungau, Kaiaia, Te Tou o Roro, Taka-poruruku, Tapa-huarau, Nga Puke-pango, Maunga-turoto, and Maunga-kawakawa. On the western edge of town, Kaikohe Hill rises 300 m above sea level, allowing views of the imposing sand dunes on the Hokianga Harbour to the west, farmlands to the east and south toward Mount Hikurangi (625 m). To the north of the Putahi volcanic ridge is Lake Ōmāpere, five km in length, but only two to three m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
New Zealand
New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island country by area, covering . New Zealand is about east of Australia across the Tasman Sea and south of the islands of New Caledonia, Fiji, and Tonga. The country's varied topography and sharp mountain peaks, including the Southern Alps, owe much to tectonic uplift and volcanic eruptions. New Zealand's capital city is Wellington, and its most populous city is Auckland. The islands of New Zealand were the last large habitable land to be settled by humans. Between about 1280 and 1350, Polynesians began to settle in the islands and then developed a distinctive Māori culture. In 1642, the Dutch explorer Abel Tasman became the first European to sight and record New Zealand. In 1840, representatives of the United Kingdom and Māori chiefs ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kaikohe-Bay Of Islands Volcanic Field
The recently active basaltic Kaikohe-Bay of Islands volcanic field in the Northland Region of New Zealand is associated geographically with an older region of extinct volcanism to its north the Wairakau Volcanic Centre, meaning eruptions in this region have occurred over the last 20 million years. All the cones older than 2 million years have eroded away, leaving plateaus from Ōkaihau to Kerikeri and north to Whangaroa from the old andesite/dacite stratovolcanoes of the Wairakau Volcanic Centre and the ten million year old or more recent volcanoes in field towards the south. In the southern part of the field, around 12 small basaltic scoria cones, and a rhyolite dome erupted in the last 500,000 years around Kaikohe. The field is considered dormant, rather than extinct. Tectonics The field is part of the eastern Northland volcanic belt which extends south to the Whangārei volcanic field near Whangarei and the south east volcanics of the Taurikura volcanic complex as found in t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scoria
Scoria is a pyroclastic, highly vesicular, dark-colored volcanic rock that was ejected from a volcano as a molten blob and cooled in the air to form discrete grains or clasts.Neuendorf, K.K.E., J.P. Mehl, Jr., and J.A. Jackson, eds. (2005) ''Glossary of Geology'' (5th ed.). Alexandria, Virginia, American Geological Institute. 779 pp. It is typically dark in color (generally dark brown, black or purplish-red), and basaltic or andesitic in composition. Scoria is relatively low in density as a result of its numerous macroscopic ellipsoidal vesicles, but in contrast to pumice, all scoria has a specific gravity greater than 1, and sinks in water. The holes or vesicles form when gases that were dissolved in the magma come out of solution as it erupts, creating bubbles in the molten rock, some of which are frozen in place as the rock cools and solidifies. Scoria may form as part of a lava flow, typically near its surface, or as fragmental ejecta (lapilli, blocks and bombs), for inst ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Putahi
Putahi is a 381 m high rhyolite dome, in the Kaikohe-Bay of Islands volcanic field in New Zealand. To the north of Putahi is Lake Ōmāpere. To its north east are the volcanoes of Tarahi and Te Ahuahu. It was the site of the first, successful for the British, battle of the Flagstaff War of 1845–46 against Hone Heke's Ngāpuhi tribe fraction. Lieutenant-Colonel William Hulme and his force of about 200 soldiers, marines and volunteers having destroyed a coastal pā at Ōtuihu moved on Hone Heke at his new pā (Te Mawhe Pā) on the Lake Ōmāpere side of Puketutu which they arrived at on 7th May 1845 before its fortifications were fully complete. However the next day, they were attacked on the flank by a force of 140 fighters led by Te Ruki Kawiti and as the British dealt with this, Hone Heke attacked from the pā defences. In the fierce running battle that ensured the Ngāpuhi Ngāpuhi (or Ngā Puhi) is a Māori iwi associated with the Northland region of New Zealand ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tarahi
Tarahi is a village development committee in Saptari District in the Sagarmatha Zone of south-eastern Nepal. At the time of the 1991 Nepal census The 1991 Nepal census was a widespread national census conducted by the Nepal Central Bureau of Statistics. Working with Nepal's Village Development Committees at a district level, they recorded data from all the main towns and villages of each ... it had a population of 3211 people living in 630 individual households. References Populated places in Saptari District VDCs in Saptari District {{Saptari-geo-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Basalt
Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial planet, rocky planet or natural satellite, moon. More than 90% of all volcanic rock on Earth is basalt. Rapid-cooling, fine-grained basalt is chemically equivalent to slow-cooling, coarse-grained gabbro. The eruption of basalt lava is observed by geologists at about 20 volcanoes per year. Basalt is also an important rock type on other planetary bodies in the Solar System. For example, the bulk of the plains of volcanism on Venus, Venus, which cover ~80% of the surface, are basaltic; the lunar mare, lunar maria are plains of flood-basaltic lava flows; and basalt is a common rock on the surface of Mars. Molten basalt lava has a low viscosity due to its relatively low silica content (between 45% and 52%), resulting in rapidly moving lava flo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rhyolite
Rhyolite ( ) is the most silica-rich of volcanic rocks. It is generally glassy or fine-grained (aphanitic) in texture, but may be porphyritic, containing larger mineral crystals (phenocrysts) in an otherwise fine-grained groundmass. The mineral assemblage is predominantly quartz, sanidine, and plagioclase. It is the extrusive equivalent to granite. Rhyolitic magma is extremely viscous, due to its high silica content. This favors explosive eruptions over effusive eruptions, so this type of magma is more often erupted as pyroclastic rock than as lava flows. Rhyolitic ash-flow tuffs are among the most voluminous of continental igneous rock formations. Rhyolitic tuff has been extensively used for construction. Obsidian, which is rhyolitic volcanic glass, has been used for tools from prehistoric times to the present day because it can be shaped to an extremely sharp edge. Rhyolitic pumice finds use as an abrasive, in concrete, and as a soil amendment. Description Rhyolite i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dacite
Dacite () is a volcanic rock formed by rapid solidification of lava that is high in silica and low in alkali metal oxides. It has a fine-grained (aphanitic) to porphyritic texture and is intermediate in composition between andesite and rhyolite. It is composed predominantly of plagioclase feldspar and quartz. Dacite is relatively common, occurring in many tectonic settings. It is associated with andesite and rhyolite as part of the subalkaline volcanic rock, subalkaline tholeiite, tholeiitic and calc-alkaline magma series. Composition Dacite consists mostly of plagioclase feldspar and quartz with biotite, hornblende, and pyroxene (augite or enstatite). The quartz appears as rounded, corroded phenocrysts, or as an element of the ground-mass. The plagioclase in dacite ranges from oligoclase to andesine and labradorite. Sanidine occurs, although in small proportions, in some dacites, and when abundant gives rise to rocks that form rhyodacite, transitions to the rhyolites. The rel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Andesite
Andesite () is a volcanic rock of intermediate composition. In a general sense, it is the intermediate type between silica-poor basalt and silica-rich rhyolite. It is fine-grained (aphanitic) to porphyritic in texture, and is composed predominantly of sodium-rich plagioclase plus pyroxene or hornblende. Andesite is the extrusive equivalent of plutonic diorite. Characteristic of subduction zones, andesite represents the dominant rock type in island arcs. The average composition of the continental crust is andesitic. Along with basalts, andesites are a component of the Martian crust. The name ''andesite'' is derived from the Andes mountain range, where this rock type is found in abundance. It was first applied by Christian Leopold von Buch in 1826. Description Andesite is an aphanitic (fine-grained) igneous rock that is intermediate in its content of silica and low in alkali metals. It has less than 20% quartz and 10% feldspathoid by volume, with at least 65% of the fe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ignimbrite
Ignimbrite is a type of volcanic rock, consisting of hardened tuff. Ignimbrites form from the deposits of pyroclastic flows, which are a hot suspension of particles and gases flowing rapidly from a volcano, driven by being denser than the surrounding atmosphere. New Zealand geologist Patrick Marshall (1869-1950) coined the term ''ignimbrite'' from the Latin ''igni-'' [fire] and ''imbri-'' [rain]. Ignimbrites are made of a very poorly sorted mixture of volcanic ash (or tuff when Lithification, lithified) and pumice lapilli, commonly with scattered lithic fragments. The ash is composed of glass shards and crystal fragments. Ignimbrites may be loose and unconsolidated, or lithified (solidified) rock called lapilli-tuff. Near the volcanic source, ignimbrites often contain thick accumulations of lithic blocks, and distally, many show meter-thick accumulations of rounded cobbles of pumice. Ignimbrites may be white, grey, pink, beige, brown, or black depending on their composition and d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Intrusive Rock
Intrusive rock is formed when magma penetrates existing rock, crystallizes, and solidifies underground to form ''Igneous intrusion, intrusions'', such as batholiths, dike (geology), dikes, Sill (geology), sills, laccoliths, and volcanic necks.Intrusive RocksIntrusive rocks accessdate: March 27, 2017.Igneous intrusive rocks, accessdate: March 27, 2017.Britannica.comintrusive rock , geology , Britannica.com accessdate: March 27, 2017. Intrusion is one of the two ways igneous rock can form. The other is extrusive rock, extrusion, such as a Types of volcanic eruptions, volcanic eruption or similar event. An intrusion is any body of intrusive igneous rock, formed from magma that cools and solidifies within the crust of the planet. In contrast, an ''extrusion'' consists of extrusive rock, formed above the surface of the crust. Some geologists use the term plutonic rock synonymously with intrusive rock, but other geologists subdivide intrusive rock, by crystal size, into coarse-grai ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
