Earth's structure

• Earth's structure


  The Earth is made up of three layers: the core, the mantle, and the crust
• Layers of the core


  • Inner core
  • Outer core
• Crust


  • It is a thin part of the Earth's structure, made from different rock types, and is made up of huge pieces of land called tectonic plates
• Mantle


  Made from semi-solid rock
• Core


  Believed to be made from iron and nickel
• Inner core


  • Solid
• Outer core


  • Liquid - the only liquid layer of the Earth's structure
• How we know about the Earth's structure

  1. The crust can be easily investigated by digging up rocks and minerals

  2. Scientists use evidence about the way waves from earthquakes and explosions travel through the Earth to make deductions about layers that cannot be seen
• Rocks


  Mixtures of minerals found in the Earth's crust
• Minerals


  Chemical compounds found in the Earth's crust
• Types of rocks


  • Sedimentary rocks
  • Igneous rocks
  • Metamorphic rocks
• Sedimentary rocks


  • Formed from layers of sediment, and can contain fossils
• Fossils


  Formed from the hard parts of an animal (shell or skeleton) that are trapped in sediments when they turn into rocks, and are replaced with minerals over time
• Igneous rocks


  • Formed from cooled magma or lava, with minerals arranged in crystals
• Magma


  Molten rock found below the Earth's surface
• Lava


  Molten rock found on the surface of the Earth
• Crystal size in igneous rocks

  • Large crystals mean the rock has cooled slowly underground (intrusive igneous rock)
  • Small crystals mean the rock has cooled quickly above ground (extrusive igneous rock)
• Metamorphic rocks


  • Formed from existing sedimentary or igneous rocks placed under extreme temperature and pressure over a long period of time
• Sedimentary rocks


  • Limestone, chalk, and sandstone
• Intrusive igneous rocks


  • Granite
• Extrusive igneous rocks


  • Basalt and obsidian
• Metamorphic rocks


  • Marble, slate, and schist
• The rock cycle


  Over millions of years, rocks are converted from one type to another, such as sedimentary to metamorphic, through very slow processes involving weathering and erosion
• Weathering


  The breaking down of large rocks to smaller bits
• Types of weathering


  • Physical
  • Chemical
  • Biological
• Physical weathering


  Caused by physical processes such as freeze-thaw, wind, rain, and waves
• Freeze-thaw weathering


  Water enters a crack in a rock, freezes and expands, making the crack larger, causing bits of rock to break off
• Chemical weathering


  The weathering of rocks by chemicals, such as acidic rainwater reacting with minerals in the rock
• Biological weathering


  Caused by animals burrowing into cracks in rocks and plants growing in cracks, forcing them to widen and break away
• Erosion


  Smaller rocks and particles caused by weathering are transported by moving water, ice, or wind
• Earth's structure


  The Earth is made up of three layers: the core, the mantle, and the crust
• Layers of the core


  • Inner core
  • Outer core
• Crust


  • It is a thin part of the Earth's structure, made from different rock types, and is made up of huge pieces of land called tectonic plates
• Mantle


  Made from semi-solid rock
• Core


  Believed to be made from iron and nickel
• Inner core


  • Solid
• Outer core


  • Liquid - the only liquid layer of the Earth's structure
• How we know about the Earth's structure

  1. The crust can be easily investigated by digging up rocks and minerals

  2. Scientists use evidence about the way waves from earthquakes and explosions travel through the Earth to make deductions about layers that cannot be seen
• Rocks


  Mixtures of minerals found in the Earth's crust
• Minerals


  Chemical compounds found in the Earth's crust