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NCERT Summary: Inside our Earth | Geography for UPSC CSE PDF Download

Introduction

Interior of the EarthInterior of the Earth

  • Crust- uppermost layer over the earth s surface, thinnest of all the layers, 35 km. on the continental masses and only 5 km. on the ocean floors.
  • Sial- The main mineral constituents of the continental mass are silica and alumina
  • Sima-The oceanic crust mainly consists of silica and magnesium
  • Mantle-Just beneath the crust extends up to a depth of 2900 km below the crust.
  • Nife- innermost layer, the radius of about 3500 km, mainly made up of nickel and iron. Do you know?
  • The crust forms only 1 percent of the volume of the earth, 84 percent consists of the mantle and 15 percent makes the core.
  • The radius of the earth is 6371 km. the central core has a very high temperature and pressure. 
    Question for NCERT Summary: Inside our Earth
    Try yourself:Which one of the following is the dominant element of the earth crust? 
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Rocks and Minerals

Three major types of rocks: igneous rocks, sedimentary rocks, and metamorphic rocks.

1. Igneous rocks

  • When the molten magma cools, it becomes solid. Rocks thus formed are called igneous rocks also called primary rocks
  • Two types of igneous rocks: intrusive rocks and extrusive rocks
  • Extrusive igneous rocks-
  • When molten lava comes on the earth’s surface, it rapidly cools down and becomes solid.
  • Rocks formed in such a way on the crust.
  • They are very fine-grained structure. For example, basalt
  • Deccan plateau is made up of basalt rocks

Intrusive igneous rocks

  • When the molten magma cools down deep inside the earth’s crust, solid rocks are formed.
  • Solid rocks so formed are called intrusive igneous rocks.
  • Form large grains.
  • Granite is an example of such a rock.
  • Sediments: smaller particles of rocks

2. Sedimentary rocks

  • Loose sediments are compressed and hardened to form layers of rocks, sandstone is made from grains of sand. These rocks may also contain fossils of plants, animals, and other microorganisms that once lived on them.

3. Metamorphic rocks

  • Igneous and sedimentary rocks can change into metamorphic rocks under great heat and pressure.
  • For example, clay changes into slate and limestone into marble.

Minerals

  • Minerals are very important to humankind. Some are used as fuels. For example, coal, natural gas, and petroleum.
  • They are also used in industries - iron, aluminium, gold, uranium, etc, in medicine, in fertilizers, etc.

Mind map 

NCERT Summary: Inside our Earth | Geography for UPSC CSE

The document NCERT Summary: Inside our Earth | Geography for UPSC CSE is a part of the UPSC Course Geography for UPSC CSE.
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FAQs on NCERT Summary: Inside our Earth - Geography for UPSC CSE

1. What are rocks and minerals?
Ans. Rocks are naturally occurring solid materials composed of minerals. Minerals, on the other hand, are naturally occurring inorganic substances with a specific chemical composition and a crystalline structure.
2. How are rocks and minerals formed?
Ans. Rocks are formed through various processes such as cooling and solidification of molten lava or magma, deposition and compaction of sediments, and metamorphism. Minerals are formed through crystallization from magma or lava, precipitation from solution, or through biological processes.
3. What is the difference between rocks and minerals?
Ans. The main difference between rocks and minerals is that rocks are composed of one or more minerals, while minerals are individual substances with a specific chemical composition and crystal structure. Rocks are larger in size and can be made up of multiple minerals.
4. How do rocks and minerals play a role in our daily lives?
Ans. Rocks and minerals have numerous uses in our daily lives. They are used in construction materials, such as granite and limestone for buildings and roads. Minerals like quartz are used in electronic devices, and metals like iron and aluminum are used in manufacturing industries. Rocks and minerals are also used in jewelry and as gemstones.
5. How can we identify different rocks and minerals?
Ans. Different rocks and minerals have distinct physical and chemical properties that can be used for identification. Physical properties include color, hardness, luster, and crystal shape. Chemical tests, such as acid reactions or flame tests, can also help identify certain minerals. Additionally, the use of specialized equipment like a microscope or spectrometer can aid in identification.
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