The Earth

• Layers of the Earth

  • Crust
  • Mantle
  • Inner core
  • Outer core
• Composition of the Earth's atmosphere

  • Nitrogen (78%)
  • Oxygen (21%)
  • Carbon dioxide (1%)
• Types of rock


  • Sedimentary
  • Igneous
  • Metamorphic
• Weathering


  The breakdown of rocks into smaller fragments
• Types of weathering


  • Biological
  • Chemical
  • Physical
• Biological weathering


  • Animal - Digging holes for food/shelter
  • Plants - Roots growing into rock cracks
• Physical weathering


  • Exfoliation (hot weather)
  • Freeze-thaw (melting and freezing of water)
• Chemical weathering


  By acid rain
• Erosion


  The movement of weathered rock fragments
• Types of transportation


  • Wind
  • Water
  • Glaciers
• Abrasion


  Pieces of rock bumping into each other and knocking off bits
• Sediments

  Small pieces of rock carried by a river
• Deposition


  When sediments fall to the bottom of seas/rivers
• Obtaining rocks


  Digging them up in mines and quarries
• Formation of sedimentary rock


  1. Sediment transported to sea

  2. Sediment deposited and compacted

  3. Sediment cemented together

  4. Fossils trapped
• Compaction


  Grains of sediment forced closer together
• Cementation


  Minerals 'gluing' sediment grains together
• Sedimentary rocks


  • Limestone
  • Sandstone
  • Mudstone
  • Chalk
• Properties of sedimentary rock

  • Soft
  • Crumbly
  • Porous
  • Layered
  • Contains fossils
• Magma


  Molten rock found deep underground
• Lava


  Magma that erupts and falls on the ground
• Formation of igneous rock

  1. Magma cools and solidifies

  2. Extrusive igneous rocks form when magma cools above surface

  3. Intrusive igneous rocks form when magma cools below surface
• Igneous rocks


  • Basalt
  • Granite
• Extrusive igneous rock


  Basalt (contains small crystals as lava cools quickly)
• Intrusive igneous rock


  Granite (contains large crystals as magma cools slowly)
• Properties of igneous rock

  • Contains crystals
  • Hard
  • Not porous
  • No fossils
  • Crystal size depends on cooling rate
• Formation of metamorphic rock

  Sedimentary rocks transformed by extreme pressure and temperature deep in Earth
• Metamorphic rocks


  • Marble
  • Quartzite
  • Slate
  • Gneiss
• Properties of metamorphic rock

  • Hard
  • Contains crystals in bands
  • Denser and harder than sedimentary
• Uplift


  Rocks moving upwards above the surface due to pressure from rocks forming underneath