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Clipperton Rock
Clipperton Rock is the highest point on Clipperton Island at 29 metres above sea level. Geography Clipperton Rock is located in the southeast of Clipperton Island. It constitutes the only emerged point of a chain of submarine mountains and volcanoes known as the East Pacific Rise. It is composed of trachyandesite and constitutes the last fragment of the neck of the volcano before becoming dormant. Elongated in shape and approximately a hundred meters in length the rock has many cavities large enough to walk though. It rises to an altitude of 29 meters, almost entirely surrounded by the waters of the lagoon it is only connected to the rest of the atoll by a narrow strip of land to the east. A geodetic marker from the IGN ''IGN'' is an American video gaming and entertainment media website operated by IGN Entertainment Inc., a subsidiary of Ziff Davis, Inc. The company's headquarters is located in San Francisco's SoMa district and is headed by its former e ... has bee ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clipperton Island
Clipperton Island ( ; ), also known as Clipperton Atoll and previously as Clipperton's Rock, is an uninhabited French coral atoll in the eastern Pacific Ocean. The only French territory in the North Pacific, Clipperton is from Paris, France; from Papeete, French Polynesia; and from Acapulco, Mexico. Clipperton was documented by French merchant-explorers in 1711 and formally claimed as part of the French protectorate of Tahiti in 1858. Despite this, American guano miners began working the island in the early 1890s. As interest in the island grew, Mexico asserted a claim to the island based upon Spanish records from the 1520s that may have identified the island. Mexico established a small military colony on the island in 1905, but during the Mexican Revolution contact with the mainland became infrequent, most of the colonists died, and lighthouse keeper Victoriano Álvarez instituted a short, brutal reign as "king" of the island. Eleven survivors were rescued in 1917 and Cli ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
East Pacific Rise
The East Pacific Rise (EPR) is a mid-ocean rise (usually termed an oceanic rise and not a mid-ocean ridge due to its higher rate of spreading that results in less elevation increase and more regular terrain), at a divergent tectonic plate boundary, located along the floor of the Pacific Ocean. It separates the Pacific plate to the west from (north to south) the North American plate, the Rivera plate, the Cocos plate, the Nazca plate, and the Antarctic plate. It runs south from the Gulf of California in the Salton Sea basin in Southern California to a point near , where it joins the Pacific-Antarctic Ridge (PAR) trending west-south-west towards Antarctica, near New Zealand (though in some uses the PAR is regarded as the southern section of the EPR). Much of the rise lies about off the South American coast and reaches a height about above the surrounding seafloor. Overview The oceanic crust is moving away from the East Pacific Rise to either side. Near Easter Island th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trachyandesite
Trachyandesite is an extrusive igneous rock with a composition between trachyte and andesite. It has little or no free quartz, but is dominated by sodic plagioclase and alkali feldspar. It is formed from the cooling of lava enriched in alkali metals and with an intermediate content of silica. The term ''trachyandesite'' had begun to fall into disfavor by 1985 but was revived to describe extrusive igneous rocks falling into the S3 field of the TAS classification. These are divided into sodium-rich benmoreite and potassium-rich latite. Trachyandesitic magma can produce explosive Plinian eruptions, such as happened at Tambora in 1815. The Eyjafjallajökull 2010 eruption (VEI-4), which disrupted European and transatlantic air travel from 15-20 April 2010, for some time was dominated by trachyandesite. Petrology Trachyandesite is characterized by a silica content near 58% and a total alkali oxide content near 9%. This places trachyandesite in the S3 field of the TAS diagr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Institut National De L'information Géographique Et Forestière
The (; "National Institute of Geographic and Forest Information"), previously (; "National Geographic Institute") and still abbreviated as IGN, is a French public state administrative establishment founded in 1940 to produce and maintain geographical information for France and its overseas departments and territories. Administrative organisation The IGN depends on the French Ministry of Equipment, Transport, Town and Country Planning, Tourism and Sea. Its missions are fixed by decrees. State subsidies represent 51% of the budget, and sales 49%. The IGN runs four laboratories to research geographical information acquisition, production, distribution and applications. It also runs its own school to teach techniques to its staff and other students: '' École nationale des sciences géographiques'' (English: National School of Geographical Sciences) or ENSG. Missions The IGN is responsible for the management and updating of: * geodetic and levelling networks, * aerial p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volcanic Plugs
A volcanic plug, also called a volcanic neck or lava neck, is a volcano, volcanic object created when magma hardens within a Volcanic vent, vent on an active volcano. When present, a plug can cause an extreme build-up of high gas pressure if rising Volatile (astrogeology)#Igneous petrology, volatile-charged magma is trapped beneath it, and this can sometimes lead to an explosive eruption. In a plinian eruption the plug is destroyed and ash is ejected. Glaciation, Glacial erosion can lead to exposure of the plug on one side, while a long slope of material remains on the opposite side. Such landforms are called crag and tail. If a plug is preserved, erosion may remove the surrounding rock while the erosion-resistant plug remains, producing a distinctive upstanding landform. Examples of volcanic plugs Africa Near the village of Rhumsiki in the Far North Region (Cameroon), Far North Province of Cameroon, Kapsiki Peak is an example of a volcanic plug and is one of the most phot ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
