NCERT Class 7 Geography Chapter 2: Inside Our Earth YouTube Lecture Handouts

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NCERT Class 7 Geography Chapter 2: Inside Our Earth

Onion Peel: Demonstrating Earth՚S Interior

Demonstrating Earths Interior
Reference Article

Crust

  • Continental - Silica & Aluminum (SIAL) – 35 km
  • Oceanic – Silica & Magnesium (SIMA) – 5 km
  • B/w upper & lower crust – Conrad Discontinuity
  • B/w crust & mantle – Moho Discontinuity
  • Jigsaw puzzle
  • Thinnest Layer

Mantle

  • About 2900 km thick
  • 85 % by volume
  • 64 % by mass
  • Made of iron but mainly silicates
  • Asthenosphere – Upper mantle – Convection currents
    • Viscous, weak and ductile
    • Just below lithosphere
    • Main source of Magma
  • B/w Upper & lower mantle – Repetti Discontinuity
  • B/w Mantle & Core – Guttenberg Discontinuity

Core

  • Radius of about 3500 km
  • Made of Iron & Nickel (NIFE)
  • High temperature & pressure
  • 15 % of earth՚s volume
  • 32.5 % of earth՚s mass
  • B/w Outer & Inner Core – Lehmann Discontinuity
  • Outer Core – Liquid (Slow Moving – Produces Earth՚s Magnetic Field)
  • Pressure, Density increases towards center

Rocks

  • Earth՚s Crust
  • Natural mass of matter that makes the crust
  • Differ in Size, Color & Texture
  • 3 Types of Rocks
  • Igneous
  • Sedimentary
  • Metamorphic

Igneous Rocks

  • Molten Magma Cools & Solidifies
  • Also known as Primary Rocks
  • Two Types
    • Intrusive – Cools inside, Slowly cools, Forms Large grains - Granite
    • Extrusive – Comes on Surface – Basalt (Deccan Plateau) – Fine Grained

Sedimentary Rocks

  • Rocks roll, crack & hit to break
  • Sediments are transported
  • Then compressed & hardened
  • Sandstone – made from sand
  • Red Fort – red sandstone
  • Include fossils

Metamorphic Rocks

  • Igneous & Metamorphic change under heat & pressure
  • Clay Slate
  • Limestone Marble
  • Taj Mahal – White Marble

Rock Cycle – Transformation

Rock Cycle - Transformation
Rock Cycle and 3 Types of Rocks - Sedimentary, Igneous, and Metamorphic

Minerals

  • Naturally occurring substances
  • Have certain physical properties
  • Definite chemical composition
  • Fuels – Coal, Petroleum & Natural Gas
  • Industries – Iron, Aluminum
  • Medicines – Calcium, Phosphorus, Magnesium

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