{"id":150367,"date":"2022-04-26T15:00:23","date_gmt":"2022-04-26T09:30:23","guid":{"rendered":"https:\/\/www.aakash.ac.in\/blog\/?p=150367"},"modified":"2023-07-10T17:54:35","modified_gmt":"2023-07-10T12:24:35","slug":"what-are-the-layers-of-the-earth-concept-notes-for-cbse-class-7-geography","status":"publish","type":"post","link":"https:\/\/www.aakash.ac.in\/blog\/what-are-the-layers-of-the-earth-concept-notes-for-cbse-class-7-geography\/","title":{"rendered":"What are the 3 layers of the Earth? Concept notes for CBSE Class 7 Geography"},"content":{"rendered":"

The Earth is round in shape. It looks like a tennis ball. But if we open it up, will it be hollow from the inside like a tennis ball? No. Earth comprises three parts \u2014 the geosphere, the hydrosphere and the atmosphere. The geosphere is the solid part of the Earth composed of minerals, rock formations, and the soil where we walk.\u00a0<\/span><\/p>\n

The hydrosphere contains all the water on the Earth. Approximately 70% of Earth is covered with water. This water is found in a liquid state in the form of streams, seas, lakes, oceans, and rivers; and in a solid-state in the form of icebergs. It is further divided into layers \u2014 the stratosphere, the troposphere, the mesosphere, the thermosphere, and the exosphere.\u00a0<\/span><\/p>\n

It is important for life on Earth because it regulates the temperature, stores the air we breathe and protects us from ultraviolet rays and intense sunlight. The atmosphere, together with the hydrosphere, regulates the water cycle.\u00a0<\/span><\/p>\n

When we analyse the structure of the geosphere from the inside, we find out that it is made up of three layers \u2014 crust, mantle and core.<\/span><\/p>\n

Layers of the earth<\/span><\/h3>\n

Suppose we open up a boiled egg. We find that it has different layers – the outermost layer is the hard outer shell made of calcium, then comes the white layer called albumin and the innermost layer is\u00a0 the yellow yolk.\u00a0<\/span><\/p>\n

Similarly, earth is made up of several concentric layers.\u00a0<\/span><\/p>\n

    \n
  1. Crust: It is the outermost layer of the Earth on which we live. It is thin, hard and strong. Earth involves land as well as oceans. The outer part of\u00a0 the earth in the land is called the continental crust, while the outer part of the earth involving the oceans is called the oceanic crust. The size of the oceanic and continental crust is different from each other. The continental crust is around 35 km deep, while the oceanic crust is only 5 km deep. Oceanic crust is\u00a0 compressed; it is formed of silica and magnesium. So, it is called sima (si-silica and ma-magnesium). Even though the oceanic crust\u00a0 is smaller than the continental crust, it is heavier because its material is dense and heavy. It mainly contains silica and alumina. So, it is called sial (si-silica and al-aluminium). Crust constitutes 1% of the earth by volume. It is further divided into three layers \u2014 sedimentary layer, granitic layer, and basaltic layer. Conrad discontinuity is found between the granitic and basaltic layers. The Earth\u2019s crust is thinnest in valleys and thickest under mountain ranges.<\/span><\/li>\n
  2. Mantle: It is the second and the thickest layer of the earth. It contains molten magma, so it is not solid. It is in a semi-liquid state as it is viscous material. The material inside the mantle is more viscous than tar, used in building roads. Magma is contained within the magma chamber. The temperature in different parts of the mantle varies depending on how close it is to the core. The mantle extends up to a depth of 2900 km below the crust. It is further divided into \u2014 the outer mantle and the inner mantle. Mantle constitutes 84% of the earth by volume. The speed of earthquake waves in the mantle is 7.9 to 8.1 km. The outer mantle has a higher viscosity than the inner mantle. The space between the crust and mantle is called Moho’s discontinuity. The interior of the mantle moves, but very slowly. This movement is responsible for moving the tectonic plates, and when they collide, earthquakes occur.\u00a0<\/span><\/li>\n
  3. Core: It is the deepest layer of the Earth. It is spherical. The length of the core is about 3500 km. It is made up of nickel and iron. So, it is called nife (ni-nickel and fe-ferrous\/iron). Core constitutes 15% of the earth by volume and 32% of the earth by mass. It is further divided into\u2014 the outer core and the inner core. The outer core lies 2900 km to 5100 km deep to the earth\u2019s surface. It contains some electrically charged particles. It is the liquid part of the core. The inner core lies 5100 km to 6378 km deep to the earth\u2019s surface. The density of this part ranges between 11 to 13.6. It is solid. It is mainly made of iron. The temperature in the inner core ranges from 5000 to 6000 degrees celsius. You might be wondering why is the inner core solid despite such high temperatures? The pressure in the inner core is so high that the material gets solidified.\u00a0<\/span><\/li>\n<\/ol>\n

    Mechanical divisions of the Earth<\/span><\/h3>\n

    On this basis, the Earth is divided into three layers.<\/span><\/p>\n

      \n
    1. Lithosphere: The term litho means rock. It is the outermost layer. It consists of crust (continental crust and oceanic crust) and the upper part of the outer mantle.<\/span><\/li>\n
    2. Asthenosphere: It is the second layer of the Earth. It consists of the lower part of the outer mantle.<\/span><\/li>\n
    3. Mesosphere: It consists of the inner mantle.<\/span><\/li>\n
    4. Barysphere: It\u00a0 consists of the core of the Earth.<\/span><\/li>\n<\/ol>\n

      Rocks and minerals of the Earth<\/span><\/h3>\n

      Rocks the natural mass of mineral matter. There are three major types of rocks on the earth which form the earth’s crust:<\/span><\/p>\n

        \n
      1. Igneous rocks<\/span><\/li>\n
      2. Sedimentary rocks<\/span><\/li>\n
      3. Metamorphic rocks<\/span><\/li>\n<\/ol>\n
          \n
        1. Igneous rocks: The name igneous is derived from the Latin word ignis, meaning fire. The eruption of volcanoes produces lava in the form of\u00a0 molten magma. When molten magma cools and deposits, it becomes solid and forms igneous rocks. Igneous rocks are also called primary rocks. This is\u00a0 because these are the first rocks to be formed. Sedimentary and metamorphic rocks are derived from it. There are two types of igneous rocks – intrusive rocks and extrusive rocks. When the lava erupts, molten magma is released. This molten magma comes on the Earth\u2019s surface, cools down and solidifies. Rocks formed in this way are called extrusive igneous rocks. They have a very fine, grained structure. For example, Basalt. The Deccan plateau in India is made up of such rocks. If the molten magma doesn\u2019t come out on the Earth\u2019s surface, rather it cools down deep inside the earth\u2019s crust, intrusive rocks are formed. Since they cool down slowly, they form larger grains. For example, Granite<\/span><\/li>\n
        2. Sedimentary rocks: The name sedimentary is\u00a0 derived from the Latin word sedimentum, meaning settle down. When igneous rocks roll down, crack and hit each other, they are broken down into small fragments called sediments. These loose sediments are\u00a0 compressed and hardened to form layers of rocks called sedimentary rocks. Sediments are transported and deposited by wind and water. Sedimentary rocks contain fossils of plants, animals, and other microorganisms that once lived on them. For example, sandstone is made from grains of sand.\u00a0<\/span><\/li>\n
        3. Metamorphic rocks: The name Metamorphic is derived from the Greek word metamorphose, meaning change of form. Under heat and pressure, igneous and sedimentary rocks can change into metamorphic rocks. For example, clay changes into slate, and limestone changes into marble.<\/span><\/li>\n<\/ol>\n

          Uses of rocks:<\/span><\/h3>\n
            \n
          1. Our roads, houses and buildings are made from rocks. Taj Mahal is made of white marble.<\/span><\/li>\n
          2. Rocks contain minerals. Minerals are naturally occurring substances with certain physical properties and definite chemical compositions. These minerals are useful to us. For example, coal, natural gas, and petroleum are fuels. Iron, aluminium, gold, and uranium are used as raw materials in industries.<\/span><\/li>\n<\/ol>\n

            Fun facts about the Earth<\/span><\/p>\n

              \n
            • The inner and the outer core together are the size of planet Mars<\/span><\/li>\n
            • The core as a structural element was discovered in 1906 by R.D Oldham during his study of earthquake wreckage. It was the first such internal element of the earth to be identified\u00a0<\/span><\/li>\n
            • The Earth is continuously moving, but the movement is so slow that we don\u2019t notice it!<\/span><\/li>\n
            • Earth is the only planet in the universe that has all the favourable factors to support life<\/span><\/li>\n
            • 70% of the Earth\u2019s surface is covered by water<\/span><\/li>\n<\/ul>\n

              The inside of our Earth is dynamic, ever-changing and mysterious. It is important to know facts about the planet we live on to understand it better and find ways to avoid natural disasters and keep ourselves safe.\u00a0<\/span><\/p>\n","protected":false},"excerpt":{"rendered":"

              The Earth is round in shape. It looks like a tennis ball. But if we open it up, will it be hollow from the inside like a tennis ball? No. Earth comprises three parts \u2014 the geosphere, the hydrosphere and the atmosphere. The geosphere is the solid part of the Earth composed of minerals, rock […]<\/p>\n","protected":false},"author":1,"featured_media":140315,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3581],"tags":[3146,3147],"class_list":["post-150367","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-cbse","tag-cbse-class-7","tag-class-7-geography"],"yoast_head":"\nLayers of Earth Notes: What are the 3 layers of the Earth? CBSE Class 7 Geography<\/title>\n<meta name=\"description\" content=\"Layers of Earth: \u200b\u200bThe earth is made up of three different layers: the crust, the mantle and the core. check out important notes on what are the layers of earth and more on aakash.ac.in\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.aakash.ac.in\/blog\/what-are-the-layers-of-the-earth-concept-notes-for-cbse-class-7-geography\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Layers of Earth Notes: What are the 3 layers of the Earth? CBSE Class 7 Geography\" \/>\n<meta property=\"og:description\" content=\"Layers of Earth: \u200b\u200bThe earth is made up of three different layers: the crust, the mantle and the core. check out important notes on what are the layers of earth and more on aakash.ac.in\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.aakash.ac.in\/blog\/what-are-the-layers-of-the-earth-concept-notes-for-cbse-class-7-geography\/\" \/>\n<meta property=\"og:site_name\" content=\"Aakash Blog\" \/>\n<meta property=\"article:publisher\" content=\"https:\/\/www.facebook.com\/aakasheducation\" \/>\n<meta property=\"article:published_time\" content=\"2022-04-26T09:30:23+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2023-07-10T12:24:35+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/blogcdn.aakash.ac.in\/wordpress_media\/2018\/05\/cropped-Blog-image.png\" \/>\n\t<meta property=\"og:image:width\" content=\"640\" \/>\n\t<meta property=\"og:image:height\" content=\"853\" \/>\n\t<meta property=\"og:image:type\" content=\"image\/png\" \/>\n<meta name=\"author\" content=\"Team @Aakash\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:creator\" content=\"@aksblog\" \/>\n<meta name=\"twitter:site\" content=\"@AESL_Official\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"Team @Aakash\" \/>\n\t<meta name=\"twitter:label2\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"9 minutes\" \/>\n<!-- \/ Yoast SEO plugin. -->","yoast_head_json":{"title":"Layers of Earth Notes: What are the 3 layers of the Earth? CBSE Class 7 Geography","description":"Layers of Earth: \u200b\u200bThe earth is made up of three different layers: the crust, the mantle and the core. check out important notes on what are the layers of earth and more on aakash.ac.in","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/www.aakash.ac.in\/blog\/what-are-the-layers-of-the-earth-concept-notes-for-cbse-class-7-geography\/","og_locale":"en_US","og_type":"article","og_title":"Layers of Earth Notes: What are the 3 layers of the Earth? CBSE Class 7 Geography","og_description":"Layers of Earth: \u200b\u200bThe earth is made up of three different layers: the crust, the mantle and the core. check out important notes on what are the layers of earth and more on aakash.ac.in","og_url":"https:\/\/www.aakash.ac.in\/blog\/what-are-the-layers-of-the-earth-concept-notes-for-cbse-class-7-geography\/","og_site_name":"Aakash Blog","article_publisher":"https:\/\/www.facebook.com\/aakasheducation","article_published_time":"2022-04-26T09:30:23+00:00","article_modified_time":"2023-07-10T12:24:35+00:00","og_image":[{"width":640,"height":853,"url":"https:\/\/blogcdn.aakash.ac.in\/wordpress_media\/2018\/05\/cropped-Blog-image.png","type":"image\/png"}],"author":"Team @Aakash","twitter_card":"summary_large_image","twitter_creator":"@aksblog","twitter_site":"@AESL_Official","twitter_misc":{"Written by":"Team @Aakash","Est. reading time":"9 minutes"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"WebPage","@id":"https:\/\/www.aakash.ac.in\/blog\/what-are-the-layers-of-the-earth-concept-notes-for-cbse-class-7-geography\/","url":"https:\/\/www.aakash.ac.in\/blog\/what-are-the-layers-of-the-earth-concept-notes-for-cbse-class-7-geography\/","name":"Layers of Earth Notes: What are the 3 layers of the Earth? CBSE Class 7 Geography","isPartOf":{"@id":"https:\/\/www.aakash.ac.in\/blog\/#website"},"primaryImageOfPage":{"@id":"https:\/\/www.aakash.ac.in\/blog\/what-are-the-layers-of-the-earth-concept-notes-for-cbse-class-7-geography\/#primaryimage"},"image":{"@id":"https:\/\/www.aakash.ac.in\/blog\/what-are-the-layers-of-the-earth-concept-notes-for-cbse-class-7-geography\/#primaryimage"},"thumbnailUrl":"https:\/\/blogcdn.aakash.ac.in\/wordpress_media\/2018\/05\/cropped-Blog-image.png","datePublished":"2022-04-26T09:30:23+00:00","dateModified":"2023-07-10T12:24:35+00:00","author":{"@id":"https:\/\/www.aakash.ac.in\/blog\/#\/schema\/person\/cf47f7cea4939aa1d6f7066a7d62eff9"},"description":"Layers of Earth: \u200b\u200bThe earth is made up of three different layers: the crust, the mantle and the core. check out important notes on what are the layers of earth and more on aakash.ac.in","breadcrumb":{"@id":"https:\/\/www.aakash.ac.in\/blog\/what-are-the-layers-of-the-earth-concept-notes-for-cbse-class-7-geography\/#breadcrumb"},"inLanguage":"en-US","potentialAction":[{"@type":"ReadAction","target":["https:\/\/www.aakash.ac.in\/blog\/what-are-the-layers-of-the-earth-concept-notes-for-cbse-class-7-geography\/"]}]},{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/www.aakash.ac.in\/blog\/what-are-the-layers-of-the-earth-concept-notes-for-cbse-class-7-geography\/#primaryimage","url":"https:\/\/blogcdn.aakash.ac.in\/wordpress_media\/2018\/05\/cropped-Blog-image.png","contentUrl":"https:\/\/blogcdn.aakash.ac.in\/wordpress_media\/2018\/05\/cropped-Blog-image.png","width":640,"height":853,"caption":"10 Reasons To Solve Previous Year Question Papers To Boost Exam Confidence"},{"@type":"BreadcrumbList","@id":"https:\/\/www.aakash.ac.in\/blog\/what-are-the-layers-of-the-earth-concept-notes-for-cbse-class-7-geography\/#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https:\/\/www.aakash.ac.in\/blog\/"},{"@type":"ListItem","position":2,"name":"CBSE","item":"https:\/\/www.aakash.ac.in\/blog\/category\/cbse\/"},{"@type":"ListItem","position":3,"name":"What are the 3 layers of the Earth? Concept notes for CBSE Class 7 Geography"}]},{"@type":"WebSite","@id":"https:\/\/www.aakash.ac.in\/blog\/#website","url":"https:\/\/www.aakash.ac.in\/blog\/","name":"Aakash Blog","description":"Medical, IIT-JEE & Foundations","potentialAction":[{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https:\/\/www.aakash.ac.in\/blog\/?s={search_term_string}"},"query-input":{"@type":"PropertyValueSpecification","valueRequired":true,"valueName":"search_term_string"}}],"inLanguage":"en-US"},{"@type":"Person","@id":"https:\/\/www.aakash.ac.in\/blog\/#\/schema\/person\/cf47f7cea4939aa1d6f7066a7d62eff9","name":"Team @Aakash","image":{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/www.aakash.ac.in\/blog\/#\/schema\/person\/image\/","url":"https:\/\/secure.gravatar.com\/avatar\/8e3389fb55661953db09dd08e8c113cb006c80494aef17a284c4a0a00976005f?s=96&d=mm&r=g","contentUrl":"https:\/\/secure.gravatar.com\/avatar\/8e3389fb55661953db09dd08e8c113cb006c80494aef17a284c4a0a00976005f?s=96&d=mm&r=g","caption":"Team @Aakash"},"sameAs":["https:\/\/x.com\/aksblog"],"url":"https:\/\/www.aakash.ac.in\/blog\/author\/aksblog\/"}]}},"_links":{"self":[{"href":"https:\/\/www.aakash.ac.in\/blog\/wp-json\/wp\/v2\/posts\/150367","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.aakash.ac.in\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.aakash.ac.in\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.aakash.ac.in\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.aakash.ac.in\/blog\/wp-json\/wp\/v2\/comments?post=150367"}],"version-history":[{"count":5,"href":"https:\/\/www.aakash.ac.in\/blog\/wp-json\/wp\/v2\/posts\/150367\/revisions"}],"predecessor-version":[{"id":268326,"href":"https:\/\/www.aakash.ac.in\/blog\/wp-json\/wp\/v2\/posts\/150367\/revisions\/268326"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.aakash.ac.in\/blog\/wp-json\/wp\/v2\/media\/140315"}],"wp:attachment":[{"href":"https:\/\/www.aakash.ac.in\/blog\/wp-json\/wp\/v2\/media?parent=150367"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.aakash.ac.in\/blog\/wp-json\/wp\/v2\/categories?post=150367"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.aakash.ac.in\/blog\/wp-json\/wp\/v2\/tags?post=150367"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}