{"id":8879,"date":"2020-07-08T17:30:34","date_gmt":"2020-07-08T12:00:34","guid":{"rendered":"https:\/\/triumphias.com\/blog\/?p=8879"},"modified":"2023-04-13T10:25:08","modified_gmt":"2023-04-13T04:55:08","slug":"ocean-relief","status":"publish","type":"post","link":"https:\/\/triumphias.com\/blog\/ocean-relief\/","title":{"rendered":"Ocean Relief"},"content":{"rendered":"<h1>Ocean Relief<\/h1>\n<p><span style=\"color: #0000ff; background-color: #ffff00;\"><strong>Relevance: Prelims\/Mains: G.S paper I: World Physical Geography<\/strong><\/span><\/p>\n<p><span style=\"color: #ff0000;\"><strong>Ocean Relief<\/strong><\/span><\/p>\n<p><img decoding=\"async\" src=\"https:\/\/www.pmfias.com\/wp-content\/uploads\/2016\/01\/Major-Ocean-Relief-Features.jpg\" alt=\"Major and Minor Ocean Relief Features | PMF IAS\" \/><\/p>\n<ul>\n<li>Ocean relief is largely due to\u00a0<strong>tectonic, volcanic, erosional and depositional processes and their interactions.<\/strong><\/li>\n<li>Ocean relief features are divided into major and minor relief features.<\/li>\n<\/ul>\n<p><span style=\"color: #ff0000;\"><strong>Major Ocean Relief Features<\/strong><\/span><\/p>\n<p>Four major divisions in the ocean relief are:<\/p>\n<p><img decoding=\"async\" src=\"https:\/\/slideplayer.com\/slide\/12810096\/77\/images\/2\/OCEAN+BOTTOM+RELIEF+Four+Relief+Zones-+Continental+Shelf.jpg\" alt=\"Ocean Bottom Relief. - ppt download\" \/><\/p>\n<ol>\n<li><strong>the continental shelf,<\/strong><\/li>\n<li><strong>the continental slope,<\/strong><\/li>\n<li><strong>the continental rise,<\/strong><\/li>\n<li><strong>the Deep Sea Plain or the abyssal plain.<\/strong><\/li>\n<\/ol>\n<p><span style=\"color: #ff0000;\"><strong>Minor Ocean Relief Features<\/strong><\/span><\/p>\n<ul>\n<li><strong>Ridges,<\/strong><\/li>\n<li><strong>Hills,<\/strong><\/li>\n<li><strong>Seamounts,<\/strong><\/li>\n<li><strong>Guyots,<\/strong><\/li>\n<li><strong>Trenches,<\/strong><\/li>\n<li><strong>Canyons,<\/strong><\/li>\n<li><strong>Sleeps,<\/strong><\/li>\n<li><strong>Fracture zones,<\/strong><\/li>\n<li><strong>Island arcs,<\/strong><\/li>\n<li><strong>Atolls,<\/strong><\/li>\n<li><strong>Coral reefs,<\/strong><\/li>\n<li><strong>Submerged volcanoes and<\/strong><\/li>\n<li><strong>Sea-scarps.<\/strong><\/li>\n<\/ul>\n<p><img decoding=\"async\" src=\"https:\/\/i.pinimg.com\/736x\/58\/32\/7c\/58327c8eba3542529fe865a7f2419d2f.jpg\" alt=\"ocean-floor-topography-and-features-6-638.jpg | Continental shelf ...\" \/><\/p>\n<p><span style=\"color: #ff0000;\"><strong>Continental Shelf<\/strong><\/span><\/p>\n<ul>\n<li>Continental Shelf is the\u00a0<strong>gently sloping<\/strong>\u00a0seaward extension of continental plate.<\/li>\n<li>These extended margins of each continent are occupied by relatively\u00a0<strong>shallow seas and gulfs.<\/strong><\/li>\n<li>Continental Shelf of all oceans together cover\u00a0<strong>7.5%\u00a0<\/strong>of the total area of the oceans.<\/li>\n<li>Gradient of continental is of\u00a0<strong>1\u00b0 or even less.<\/strong><\/li>\n<li>The shelf typically ends at a very steep slope, called the\u00a0<strong>shelf break.<\/strong><\/li>\n<li>The continental shelves are covered with variable thicknesses of sediments brought down by\u00a0<strong>rivers, glaciers<\/strong>\u00a0etc..<\/li>\n<li>Massive sedimentary deposits received over a long time by the continental shelves, become the source of fossil fuels [Petroleum].<\/li>\n<li>Examples: Continental Shelf of South-East Asia, Great Banks around Newfoundland, Submerged region between Australia and New Guinea.<\/li>\n<li>The shelf is formed mainly due to<\/li>\n<\/ul>\n<ol>\n<li><strong>submergence of a part of a continent<\/strong><\/li>\n<li><strong>relative rise in sea level<\/strong><\/li>\n<li><strong>Sedimentary deposits brought down by rivers<\/strong><\/li>\n<\/ol>\n<ul>\n<li>There are various types of shelves based on different sediments of terrestrial origin \u2014<\/li>\n<\/ul>\n<ol>\n<li><strong>glaciated shelf (Surrounding Greenland),<\/strong><\/li>\n<li><strong>coral reef shelf (Queensland, Australia),<\/strong><\/li>\n<li><strong>shelf of a large river (Around Nile Delta),<\/strong><\/li>\n<li><strong>shelf with dendritic valleys (At the Mouth of Hudson River)<\/strong><\/li>\n<li><strong>shelf along young mountain ranges (Shelves between Hawaiian Islands).<\/strong><\/li>\n<\/ol>\n<p><span style=\"color: #ff0000;\"><strong>Width<\/strong><\/span><\/p>\n<p>The average width of continental shelves is between 70 \u2013 80 km.<\/p>\n<p>The shelves are almost absent or very narrow along some of the margins like the coasts of Chile, the west coast of Sumatra, etc. [Ocean \u2013 Continent Convergence and Ocean \u2013 Ocean Convergence].<\/p>\n<p>It is up to 120 km wide along the eastern coast of USA. On the contrary, the Siberian shelf in the Arctic Ocean, the largest in the world, stretches to 1,500 km in width.<\/p>\n<p><span style=\"color: #ff0000;\"><strong>Depth<\/strong><\/span><\/p>\n<ul>\n<li>The depth of the shelves also varies. It may be as shallow as 30 m in some areas while in some areas it is as deep as 600 m.<\/li>\n<\/ul>\n<p><span style=\"color: #ff0000;\"><strong>Importance of continent shelves<\/strong><\/span><\/p>\n<ol>\n<li><strong><em>Marine food comes almost entirely from continental shelves;<\/em><\/strong><\/li>\n<li><strong><em>They provide the richest fishing grounds;<\/em><\/strong><\/li>\n<li><strong><em>They are potential sites for economic minerals\u00a0<\/em><\/strong>[20% of the world production of\u00a0<strong>petroleum<\/strong>and gas comes from shelves.\u00a0<strong>Polymetallic nodules<\/strong>\u00a0(<strong>manganese nodules<\/strong>; concentric layers of\u00a0<strong>iron and manganese hydroxides<\/strong>) etc. are good sources of various mineral ores like manganese, iron copper, gold etc..]<\/li>\n<\/ol>\n<p><span style=\"color: #ff0000;\"><strong>Continental Slope<\/strong><\/span><\/p>\n<ul>\n<li>The continental slope connects the continental shelf and the ocean basins.<\/li>\n<li>It begins where the bottom of the continental shelf sharply drops off into a steep slope.<\/li>\n<li>The gradient of the slope region varies between\u00a0<strong>2-5\u00b0.<\/strong><\/li>\n<li>The depth of the slope region varies between 200 and 3,000 m.<\/li>\n<li>The seaward edge of the continental slope loses gradient at this depth and gives rise to\u00a0<strong>continental rise.<\/strong><\/li>\n<li>The\u00a0<strong>continental slope boundary indicates the end of the continents<\/strong>.<\/li>\n<li>Canyons and trenches are observed in this region.<\/li>\n<\/ul>\n<p><span style=\"color: #ff0000;\"><strong>Continental Rise<\/strong><\/span><\/p>\n<ul>\n<li>The continental slope\u00a0<strong>gradually<\/strong>\u00a0loses its steepness with depth.<\/li>\n<li>When the slope reaches a level of between\u00a0<strong>0.5\u00b0 and 1\u00b0<\/strong>, it is referred to as the continental rise.<\/li>\n<li>With increasing depth the rise becomes virtually flat and merges with the\u00a0<strong>abyssal plain.<\/strong><\/li>\n<\/ul>\n<p><span style=\"color: #ff0000;\"><strong>Deep Sea Plain or Abyssal Plain<\/strong><\/span><\/p>\n<ul>\n<li>Deep sea planes are gently sloping areas of the ocean basins.<\/li>\n<li>These are the\u00a0<strong>flattest<\/strong>\u00a0and smoothest regions of the world because of\u00a0<strong>terrigenous [<\/strong>denoting marine sediment eroded from the land<strong>] and shallow water sediments\u00a0<\/strong>that buries the irregular topography.<\/li>\n<li>It covers nearly\u00a0<strong>40%<\/strong>\u00a0of the ocean floor.<\/li>\n<li>The depths vary between 3,000 and 6,000 m.<\/li>\n<li>These plains are covered with fine-grained sediments like clay and silt.<\/li>\n<\/ul>\n<p><span style=\"color: #ff0000;\"><strong>Oceanic Deeps or Trenches<\/strong><\/span><\/p>\n<p><img decoding=\"async\" src=\"https:\/\/media.nationalgeographic.org\/assets\/photos\/676\/159\/32de5b14-c18e-49d3-b88f-6311ed6065c8.jpg\" alt=\"ocean trench | National Geographic Society\" \/><\/p>\n<ul>\n<li>The trenches are relatively steep sided, narrow basins (Depressions). These areas are the deepest parts of the oceans.<\/li>\n<li>They are of tectonic origin and are formed during ocean \u2013 ocean convergence and ocean continent convergence.<\/li>\n<li>They are some 3-5 km deeper than the surrounding ocean floor.<\/li>\n<li>The trenches lie\u00a0<strong>along the fringes of the deep-sea plain<\/strong>\u00a0at the bases of continental slopes and along island arcs.<\/li>\n<li>The trenches run\u00a0<strong>parallel to the bordering fold mountains<\/strong>\u00a0or the\u00a0<strong>island chains<\/strong>.<\/li>\n<li>The trenches are very common in the Pacific Ocean and form an almost continuous ring along the western and eastern margins of the Pacific.<\/li>\n<li>The\u00a0<strong>Mariana Trench off the Guam Islands<\/strong>\u00a0in the Pacific Ocean is the deepest trench with, a depth of more than\u00a0<strong>11 kilometres.<\/strong><\/li>\n<li>They are associated with\u00a0<strong>active volcanoes<\/strong>\u00a0and\u00a0<strong>strong earthquakes<\/strong>\u00a0(Deep Focus Earthquakes like in Japan). This makes them very significant in the study of plate movements.<\/li>\n<li>As many as 57 deeps have been explored so far; of which 32 are in the Pacific Ocean; 19 in the Atlantic Ocean and 6 in the Indian Ocean.<\/li>\n<\/ul>\n<p><span style=\"color: #ff0000;\"><strong>Mid-Oceanic Ridges or Submarine Ridges<\/strong><\/span><\/p>\n<ul>\n<li>A mid-oceanic ridge is composed of two chains of mountains separated by a large depression. [Divergent Boundary]<\/li>\n<li>The mountain ranges can have peaks as high as 2,500 m and some even reach above the ocean\u2019s surface.<\/li>\n<li>Running for a total length of\u00a0<strong>75,000 km<\/strong>, these ridges form the\u00a0<strong>largest mountain systems on earth.<\/strong><\/li>\n<li>These ridges are either broad, like a plateau, gently sloping or in the form of steep-sided narrow mountains.<\/li>\n<li>These oceanic ridge systems are of\u00a0<strong>tectonic origin<\/strong>\u00a0and provide evidence in support of the theory of\u00a0<strong>Plate Tectonics.<\/strong><\/li>\n<li>Iceland, a part of the mid-Atlantic Ridge, is an example.<\/li>\n<\/ul>\n<p><span style=\"color: #ff0000;\"><strong>Abyssal Hills<\/strong><\/span><\/p>\n<p><img decoding=\"async\" src=\"https:\/\/bclearningnetwork.com\/LOR\/media\/es11\/unit8\/U08L02\/hillmountguyot.JPG\" alt=\"Ocean Floor\" \/><\/p>\n<ul>\n<li><strong>Seamount:<\/strong>\u00a0It is a mountain with pointed summits, rising from the seafloor that\u00a0<strong>does not reach the surface<\/strong>\u00a0of the ocean. Seamounts are volcanic in origin. These can be 3,000-4,500 m tall.<\/li>\n<li>The\u00a0<strong>Emperor seamount<\/strong>, an extension of the Hawaiian Islands [Hotspot] in the Pacific Ocean, is a good example.<\/li>\n<li><strong>Guyots:\u00a0<\/strong>The flat topped mountains (seamounts) are known as guyots.<\/li>\n<li>Seamounts and guyots are very common in the Pacific Ocean where they are estimated to number around 10,000.<\/li>\n<\/ul>\n<p><span style=\"color: #ff0000;\"><strong>Submarine Canyons<\/strong><\/span><\/p>\n<p><img decoding=\"async\" src=\"https:\/\/cdn.britannica.com\/36\/139436-050-355EF761\/pitch-continental-shelf-slope-way-transition-region.jpg\" alt=\"Submarine canyon | geology | Britannica\" \/><\/p>\n<ul>\n<li><strong>CANYON:<\/strong>\u00a0a deep gorge, especially one with a river flowing through it<\/li>\n<li><strong>GORGE:<\/strong>\u00a0a steep, narrow valley or ravine<\/li>\n<li><strong>VALLEY:<\/strong>\u00a0a low area between hills or mountains or a depression, typically with a river or stream flowing through it.<\/li>\n<\/ul>\n<ul>\n<li>These are deep valleys, some comparable to the Grand Canyon of the Colorado river.<\/li>\n<li>They are sometimes found cutting across the continental shelves and slopes, often extending from the mouths of large rivers.<\/li>\n<li>The\u00a0<strong>Hudson Canyon<\/strong>\u00a0is the best known canyon in the world.<\/li>\n<\/ul>\n<p><strong>Broadly, there are three types of submarine canyons\u2014<\/strong><\/p>\n<ul>\n<li>Small gorges which begin at the edge of the continental shelf and extend down the slope to very great depths, e.g.,\u00a0<strong>Oceanographer Canyons<\/strong>\u00a0near New England.<\/li>\n<li>Those which begin at the mouth of a river and extend over the shelf, such as the Zaire, the Mississippi and the\u00a0<strong>Indus canyons<\/strong>.<\/li>\n<li>Those which have a dendritic appearance and are deeply cut into the edge of the shelf and the slope, like the canyons off the coast of southern California. The\u00a0<strong>Hudson Canyon<\/strong>\u00a0is the best known canyon in the world.<\/li>\n<li>The largest canyons in the world occur in the\u00a0<strong>Bering Sea<\/strong>\u00a0off Alaska. They are the Bering, Pribilof and Zhemchung canyons.<\/li>\n<\/ul>\n<p><span style=\"color: #ff0000;\"><strong>Atoll<\/strong><\/span><\/p>\n<p><img decoding=\"async\" src=\"https:\/\/cdn.downtoearth.org.in\/library\/large\/2019-08-28\/0.14061500_1566977190_atoll-gettyimages-.jpg\" alt=\"Atoll nations at immediate risk of climate change\" \/><\/p>\n<ul>\n<li>These are low islands found in the tropical oceans consisting of coral reefs surrounding a central depression.<\/li>\n<li>It may be a part of the sea (lagoon), or sometimes form enclosing a body of fresh, brackish, or highly saline water.<\/li>\n<\/ul>\n<p><span style=\"color: #ff0000;\"><strong>Bank, Shoal and Reef<\/strong><\/span><\/p>\n<ul>\n<li>These marine features are formed as a result of\u00a0<strong>erosional, depositional and biological activity.<\/strong><\/li>\n<li>These are produced upon features of\u00a0<strong>diastrophic [Earth Movements]<\/strong>\u00a0origin. Therefore, they are located on upper parts of elevations.<\/li>\n<\/ul>\n<p><span style=\"color: #ff0000;\"><strong>Bank<\/strong><\/span><\/p>\n<ul>\n<li>These marine features are formed as\u2019 a result of erosional and depositional activity.<\/li>\n<li>A bank is a flat topped elevation located in the continental margins.<\/li>\n<li>The depth of water here is shallow but enough for navigational purposes.<\/li>\n<li>The\u00a0<strong>Dogger Bank<\/strong>\u00a0in the North Sea and\u00a0<strong>Grand Bank<\/strong>\u00a0in the north-western Atlantic, Newfoundland are famous examples.<\/li>\n<li>The banks are sites of some of the most\u00a0<strong>productive fisheries of the world.<\/strong><\/li>\n<\/ul>\n<p><span style=\"color: #ff0000;\"><strong>Shoal<\/strong><\/span><\/p>\n<ul>\n<li>A shoal is a detached elevation with shallow depths. Since they project out of water with moderate heights, they are\u00a0<strong>dangerous for navigation.<\/strong><\/li>\n<\/ul>\n<p><span style=\"color: #ff0000;\"><strong>Reef<\/strong><\/span><\/p>\n<p>A reef is a predominantly organic deposit made by living or dead organisms that forms a mound or rocky elevation like a ridge.<\/p>\n<p>Coral reefs are a characteristic feature of the Pacific Ocean where they are associated with seamounts and guyots.<\/p>\n<p>The largest reef in the world is found off the Queensland coast of Australia. [We will study coral reefs in future posts]<\/p>\n<p>Since the reefs may extend above the surface, they are generally dangerous for navigation.<\/p>\n<p><span style=\"color: #ff0000;\"><strong>Significance of Study of Oceanic Relief<\/strong><\/span><\/p>\n<ul>\n<li>Ocean relief controls the\u00a0<strong>motion of sea water.<\/strong><\/li>\n<li>The oceanic movement in the form of currents, in turn, causes many variations in both oceans and in atmosphere.<\/li>\n<li>The bottom relief of oceans also influences\u00a0<strong>navigation and fishing.<\/strong><\/li>\n<\/ul>\n<p>&nbsp;<\/p>\n<p><span style=\"color: #0000ff;\"><strong>For more such notes, Articles, News &amp; Views Join our Telegram Channel.<\/strong><\/span><\/p>\n<p><a title=\"Telegram Link\" href=\"https:\/\/t.me\/triumphias\" target=\"_blank\"><span style=\"color: #ff0000;\"><strong>https:\/\/t.me\/triumphias<\/strong><\/span><\/a><\/p>\n<p><span style=\"color: #0000ff;\"><strong>Click the link below to see the details about the UPSC \u2013Civils courses offered by Triumph IAS.<\/strong> <\/span><span style=\"color: #ff0000;\"><strong><a style=\"color: #ff0000;\" title=\"Courses available\" href=\"https:\/\/triumphias.com\/pages-all-courses.php\">https:\/\/triumphias.com\/pages-all-courses.php<\/a><\/strong><\/span><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Ocean Relief Relevance: Prelims\/Mains: G.S paper I: World Physical Geography Ocean Relief Ocean relief is largely due to\u00a0tectonic, volcanic, erosional<\/p>\n","protected":false},"author":1,"featured_media":3514,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_exactmetrics_skip_tracking":false,"_exactmetrics_sitenote_active":false,"_exactmetrics_sitenote_note":"","_exactmetrics_sitenote_category":0,"footnotes":""},"categories":[7,15],"tags":[4620,4630,4626,4619,4617,4618,4631,4614,4636,4613,4635,4628,4638,4624,4622,4629,4615,4639,4634,4616,4610,4637,4621,4633,4623,4627,4632,4611,4625,392,4612],"class_list":["post-8879","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-general-studies-i","category-geography","tag-abyssal-plain","tag-atolls","tag-canyons","tag-continental-rise","tag-continental-shelf","tag-continental-slope","tag-coral-reefs","tag-depositional-processes","tag-economic-minerals","tag-erosional","tag-fishing-grounds","tag-fracture-zones","tag-gas","tag-guyots","tag-hills","tag-island-arcs","tag-major-ocean-relief-features","tag-manganese-nodules","tag-marine-food","tag-minor-ocean-relief-features","tag-ocean-relief","tag-petroleum","tag-ridges","tag-sea-scarps","tag-seamounts","tag-sleeps","tag-submerged-volcanoes","tag-tectonic","tag-trenches","tag-union-public-service-commission-upsc","tag-volcanic"],"amp_enabled":true,"_links":{"self":[{"href":"https:\/\/triumphias.com\/blog\/wp-json\/wp\/v2\/posts\/8879","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/triumphias.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/triumphias.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/triumphias.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/triumphias.com\/blog\/wp-json\/wp\/v2\/comments?post=8879"}],"version-history":[{"count":2,"href":"https:\/\/triumphias.com\/blog\/wp-json\/wp\/v2\/posts\/8879\/revisions"}],"predecessor-version":[{"id":14047,"href":"https:\/\/triumphias.com\/blog\/wp-json\/wp\/v2\/posts\/8879\/revisions\/14047"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/triumphias.com\/blog\/wp-json\/wp\/v2\/media\/3514"}],"wp:attachment":[{"href":"https:\/\/triumphias.com\/blog\/wp-json\/wp\/v2\/media?parent=8879"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/triumphias.com\/blog\/wp-json\/wp\/v2\/categories?post=8879"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/triumphias.com\/blog\/wp-json\/wp\/v2\/tags?post=8879"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}