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

Image of Demonstrating Earth's Interior

Image of Demonstrating Earth's Interior

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https://www.YouTube.com/watch?v=eJ5e7fhRP1M

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

Image of Rock Cycle - Transformation

Image of Rock Cycle - Transformation

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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