A group of teachers with one thing in common - we all have a passion for the subject of Geography. a group of closely scattered islands in a large body of water. 'increment': 1, var mapping_topslot_a = googletag.sizeMapping().addSize([746, 0], []).addSize([0, 550], [[300, 250]]).addSize([0, 0], [[300, 50], [320, 50], [320, 100]]).build(); Volcanoes often form a hill or mountain as layers of rock and ash build up from repeated eruptions. Another way volcanoes can form is what's known as hotspot volcanism.

params: { { bidder: 'openx', params: { unit: '539971081', delDomain: 'idm-d.openx.net' }}, Volcanic landforms have evolved over time as a result of repeated volcanic activity.
type: "html5", In other cases, entrapped gases tear the magma into shreds and hurl viscous clots of lava into the air. {code: 'ad_topslot_b', pubstack: { adUnitName: 'cdo_topslot', adUnitPath: '/2863368/topslot' }, mediaTypes: { banner: { sizes: [[728, 90]] } }, Code of Ethics.

The movement of earth’s plates create all sorts of volcanos. The more eruptions there are, the more layers of ash and lava there will be. { bidder: 'ix', params: { siteId: '195467', size: [300, 250] }}, Of the three types of volcano, the shield is the largest in terms of area. “Hot spot” volcanoes may form where plumes of lava rise from deep within the mantle to Earth's crust far from any plate margins. { bidder: 'criteo', params: { networkId: 7100, publisherSubId: 'cdo_topslot' }},

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{ bidder: 'ix', params: { siteId: '555365', size: [160, 600] }}, As the descending landmass sinks deep into the Earth, temperatures and pressures climb, releasing water from the rocks. } mountains as seen in this picture. { bidder: 'pubmatic', params: { publisherId: '158679', adSlot: 'cdo_rightslot2' }}]}]; iasLog("criterion : cdo_c = " + ["science_geographic_locales"]); Some 75 percent of the world's active volcanoes are positioned around the ring of fire, a 25,000-mile long, horseshoe-shaped zone that stretches from the southern tip of South America across the West Coast of North America, through the Bering Sea to Japan, and on to New Zealand. {code: 'ad_rightslot', pubstack: { adUnitName: 'cdo_rightslot', adUnitPath: '/2863368/rightslot' }, mediaTypes: { banner: { sizes: [[300, 250]] } },

pid: '94' { bidder: 'pubmatic', params: { publisherId: '158679', adSlot: 'cdo_topslot' }}]}, Ash is another volcanic danger. If a media asset is downloadable, a download button appears in the corner of the media viewer. A usually cone-shaped mountain formed by the materials that flowed or were thrown out from such an opening.

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But as time ticks by, the elements break down these volcanic rocks, liberating nutrients from their stony prisons and creating remarkably fertile soils that have allowed civilizations to flourish. const customGranularity = { { bidder: 'sovrn', params: { tagid: '446382' }},

– An instrument used to measure the strength of an earthquake.

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When the magma chamber empties, the support that the magma had provided inside the chamber disappears. Caryl-Sue, National Geographic Society { bidder: 'criteo', params: { networkId: 7100, publisherSubId: 'cdo_topslot' }}, Their explosive force crafts mountains as well as craters. iasLog("criterion : cdo_tc = resp"); Articles from Britannica Encyclopedias for elementary and high school students. googletag.cmd.push(function() { Clearly the destructive potential of volcanoes is tremendous. { bidder: 'onemobile', params: { dcn: '8a9690ab01717182962182bb50ce0007', pos: 'cdo_btmslot_mobile_flex' }}, "loggedIn": false

The study of these very small volcanoes is often complicated by the limited distribution of their deposits and by reworking/erosion processes. 'max': 3, the point where three tectonic plates meet.
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Other volcanoes are dormant; they are quiet for now but could become active. { bidder: 'ix', params: { siteId: '195465', size: [300, 250] }}, Once it leaves the volcano, it’s known as lava. Sustainability Policy |  'min': 0, Swarms of small earthquakes, which may be caused by a rising plug of dense, viscous magma oscillating against a sheath of more-permeable magma, may also signal volcanic eruptions, especially explosive ones. { bidder: 'triplelift', params: { inventoryCode: 'Cambridge_MidArticle' }}, { bidder: 'sovrn', params: { tagid: '446381' }}, var dfpSlots = {}; Click on the arrows to change the translation direction.