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Mount Oakan
is a stratovolcano located in Akan National Park in Hokkaidō, Japan. Geography and geology Mount Oakan sits in the Akan caldera northeast of Lake Akan. The volcano rises some above the surrounding terrain. The top of the volcano is above sea level. The volcanic cone is some in diameter. There are three explosion craters at the summit. At at about , there is a fumarole. The volcano is made mostly from non-alkali mafic volcanic rock. The main rock type is andesite and dacite. History Mount Oakan emerged in the Late Pleistocene dropping pumice on Minamishikata. After that, continuous lava flows formed the bulk of the volcano. In the final stages of its life, a parasitic volcano formed a lava dome at the summit. According to its name and local legend, Mount Oakan is the male counterpart to Mount Meakan is an active stratovolcano located in Akan National Park in Hokkaidō, Japan. It is the tallest mountain in the Akan Volcanic Complex. The volcano consists of nine overlapp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Siberian Dwarf Pine
''Pinus pumila'', commonly known as the Siberian dwarf pine, dwarf Siberian pine, dwarf stone pine, Japanese stone pine, or creeping pine, is a tree in the family Pinaceae native to northeastern Asia and the Japanese isles. It shares the common name ''creeping pine'' with several other plants. Description The Siberian dwarf pine is a coniferous evergreen shrub ranging from in height, exceptionally up to , but may have individual branches that extend farther along the ground in length. In the mountains of northern Japan, it sometimes hybridises with the related Japanese white pine ('' Pinus parviflora''); these hybrids (''Pinus'' × ''hakkodensis'') are larger than ''P. pumila'', reaching tall on occasion. The leaves are needle-like, formed in bundles of five and are 4–6 centimetres long. The cones are 2.5–4.5 cm long, with large nut-like seeds (pine nuts). Distribution The range covers the Far East, Eastern Siberia, north-east of Mongolia, north-east of China ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lake Akan Kushiro Hokkaido Japan05n
A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much larger oceans, they do form part of the Earth's water cycle. Lakes are distinct from lagoons, which are generally coastal parts of the ocean. Lakes are typically larger and deeper than ponds, which also lie on land, though there are no official or scientific definitions. Lakes can be contrasted with rivers or streams, which usually flow in a channel on land. Most lakes are fed and drained by rivers and streams. Natural lakes are generally found in mountainous areas, rift zones, and areas with ongoing glaciation. Other lakes are found in endorheic basins or along the courses of mature rivers, where a river channel has widened into a basin. Some parts of the world have many lakes formed by the chaotic drainage patterns left over from the last ic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lava Dome
In volcanology, a lava dome is a circular mound-shaped protrusion resulting from the slow extrusion of viscous lava from a volcano. Dome-building eruptions are common, particularly in convergent plate boundary settings. Around 6% of eruptions on Earth are lava dome forming. The geochemistry of lava domes can vary from basalt (e.g. Semeru, 1946) to rhyolite (e.g. Chaiten, 2010) although the majority are of intermediate composition (such as Santiaguito, dacite-andesite, present day) The characteristic dome shape is attributed to high viscosity that prevents the lava from flowing very far. This high viscosity can be obtained in two ways: by high levels of silica in the magma, or by degassing of fluid magma. Since viscous basaltic and andesitic domes weather fast and easily break apart by further input of fluid lava, most of the preserved domes have high silica content and consist of rhyolite or dacite. Existence of lava domes has been suggested for some domed structures on the Mo ... [...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] |
Mafic
A mafic mineral or rock is a silicate mineral or igneous rock rich in magnesium and iron. Most mafic minerals are dark in color, and common rock-forming mafic minerals include olivine, pyroxene, amphibole, and biotite. Common mafic rocks include basalt, diabase and gabbro. Mafic rocks often also contain calcium-rich varieties of plagioclase feldspar. Mafic materials can also be described as ferromagnesian. History The term ''mafic'' is a portmanteau of "magnesium" and "ferric" and was coined by Charles Whitman Cross, Joseph P. Iddings, Louis Valentine Pirsson, and Henry Stephens Washington in 1912. Cross' group had previously divided the major rock-forming minerals found in igneous rocks into ''salic'' minerals, such as quartz, feldspars, or feldspathoids, and ''femic'' minerals, such as olivine and pyroxene. However, micas and aluminium-rich amphiboles were excluded, while some calcium minerals containing little iron or magnesium, such as wollastonite or apatite, were included ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fumarole
A fumarole (or fumerole) is a vent in the surface of the Earth or other rocky planet from which hot volcanic gases and vapors are emitted, without any accompanying liquids or solids. Fumaroles are characteristic of the late stages of volcanic activity, but fumarole activity can also precede a volcanic eruption and has been used for eruption prediction. Most fumaroles die down within a few days or weeks of the end of an eruption, but a few are persistent, lasting for decades or longer. An area containing fumaroles is known as a fumarole field. The predominant vapor emitted by fumaroles is steam, formed by the circulation of groundwater through heated rock. This is typically accompanied by volcanic gases given off by magma cooling deep below the surface. These volcanic gases include sulfur compounds, such as various sulfur oxides and hydrogen sulfide, and sometimes hydrogen chloride, hydrogen fluoride, and other gases. A fumarole that emits significant sulfur compounds is some ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lake Akan
is a lake in Kushiro, Hokkaidō, Japan. It is located in Akan National Park and is a Ramsar Site. History Volcanic activity formed the lake some 6,000 years ago, when a lava dam was formed. The lake used to have a clarity of 8–9 meters in the 1930s. Pollution from local hotspring resorts has decreased the transparency to 3–4 meters. Flora and fauna The lake is famous for the marimo (''Aegagropila linnaei''), aggregations of algae that form into spherical shapes 2–30 cm in diameter. Other flora of the lake include the following: *Phragmites communis *Nuphar sp. *Potamogeton crispus *Hydrilla verticillata *Myriophyllum verticillatum *Vallisneria gigantea * Melosira italica *Asterionella formosa * Synedra Kokanee salmon (''Oncorhynchus nerka'') are native to Lake Akan. Other fauna of the lake include the following: *Zooplankton: **Daphnia longiremis **Bosmina coregoni **Eurytemora affinis *Bottom: **Chironomus plumosus **Tubificidae *Fish: **Cyprinus carpio **Carassius ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Akan National Park
is a national park located on the island of Hokkaidō, Japan. Along with Daisetsuzan National Park, these are the two oldest national parks in Hokkaidō. The park was established December 4, 1934. Akan is an area of volcanic craters and forests, covering . The park is famous for its crystal clear lakes, its hot springs, and its large marimo. It is the only place where marimo of appreciable size form naturally in Japan. Sites The park can be divided into two general areas, Kawayu and Akan. Kawayu Mount Iō and the Kawayu Onsen offer natural hotsprings and sulphur fumaroles. Around Lake Kussharo, a caldera lake, are Bihoro Pass, Mount Mokoto, and Mount Nishibetsu. At the lake, Wakoto Peninsula is an area with high ground temperatures and uniquely adapted wildlife. Lake Mashū is a caldera lake. It is one of the clearest lakes in the world with visibility up to 40 meters. Akan Akan Caldera is a large caldera over 20 km across. Emerging from within caldera is the Akan V ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stratovolcano
A stratovolcano, also known as a composite volcano, is a conical volcano built up by many layers (strata) of hardened lava and tephra. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile with a summit crater and periodic intervals of explosive eruptions and effusive eruptions, although some have collapsed summit craters called calderas. The lava flowing from stratovolcanoes typically cools and hardens before spreading far, due to high viscosity. The magma forming this lava is often felsic, having high-to-intermediate levels of silica (as in rhyolite, dacite, or andesite), with lesser amounts of less-viscous mafic magma. Extensive felsic lava flows are uncommon, but have travelled as far as . Stratovolcanoes are sometimes called composite volcanoes because of their composite stratified structure, built up from sequential outpourings of erupted materials. They are among the most common types of volcanoes, in contrast to the less common shield volca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kuril Arc
The Kuril Islands or Kurile Islands (; rus, Кури́льские острова́, r=Kuril'skiye ostrova, p=kʊˈrʲilʲskʲɪjə ɐstrɐˈva; Japanese: or ) are a volcanic archipelago currently administered as part of Sakhalin Oblast in the Russian Far East. It stretches approximately northeast from Hokkaido in Japan to Kamchatka Peninsula in Russia separating the Sea of Okhotsk from the north Pacific Ocean. There are 56 islands and many minor rocks. The Kuril Islands consist of the Greater Kuril Chain and the Lesser Kuril Chain. They cover an area of around , with a population of roughly 20,000. The islands have been under Russian administration since their 1945 invasion as the Soviet Union towards the end of World War II. Japan claims the four southernmost islands, including two of the three largest (Iturup and Kunashir), as part of its territory, as well as Shikotan and the Habomai islets, which has led to the ongoing Kuril Islands dispute. The disputed islands are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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