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 Earthีšs Interior

Demonstrating Earths Interior
Reference Article

Crust

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

Mantle

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

Core

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

Rocks

  • Earthีšs 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 โ€“ Cools inside, Slowly cools, Forms Large grains - Granite
    • Extrusive โ€“ Comes on Surface โ€“ Basalt (Deccan Plateau) โ€“ Fine Grained

Sedimentary Rocks

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

Metamorphic Rocks

  • Igneous & Metamorphic change under heat & pressure
  • Clay Slate
  • Limestone Marble
  • Taj Mahal โ€“ White Marble

Rock Cycle โ€“ 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 โ€“ Coal, Petroleum & Natural Gas
  • Industries โ€“ Iron, Aluminum
  • Medicines โ€“ Calcium, Phosphorus, Magnesium

โœ Manishika