Layers of the Earth

• Layers of the Earth


  The Earth is made up of 3 main layers: Crust, Mantle, Core

  
• The layers of the Earth

  Are different from one another

  
• Crust


  • Thinnest layer of the Earth that ranges from only 2 miles in some areas of the ocean floor to 75 miles deep under mountains
  • Made up of large amounts of silicon and aluminum
  • Two types: oceanic crust and continental crust
  • Composed of plates on which the continents and oceans rest

  
• Mantle


  • Solid but capable of flow (like hot asphalt or fudge)
  • Thickest layer of the Earth (making up 70% of the Earth's mass)
  • The hot material (magma) in the mantle rises to the top of the mantle, cools, then sinks, reheats, and rises again. These convection currents cause changes in the Earth's surface

  
• Upper Mantle


  • Extends from the crust to a depth of about 410 kilometers (255 miles)
  • Mostly solid, but its more malleable regions contribute to tectonic activity
  • Includes the lithosphere and asthenosphere

  
• Lithosphere

  • The solid, outer part of the Earth, extending to a depth of about 100 kilometers (62 miles)
  • Includes both the crust and the brittle upper portion of the mantle
  • The coolest and most rigid of Earth's layers

  
• Asthenosphere


  • The denser, weaker layer beneath the lithospheric mantle
  • Lies between about 100 kilometers (62 miles) and 410 kilometers (255 miles) beneath Earth's surface
  • The temperature and pressure are so high that rocks soften and partly melt, becoming semi-molten

  
• Transition Zone


  • From about 410 kilometers (255 miles) to 660 kilometers (410 miles) beneath Earth's surface
  • Rocks undergo radical transformations, becoming much, much more dense

  
• Outer Core


  • Molten (liquid) metal that is about 4,700°C (8,500°F)
  • Located about 1,800 miles beneath the crust and is about 1,400 miles thick
  • Composed of the melted metals nickel and iron
• Inner Core


  • Solid sphere composed mostly of iron
  • As hot as 6,650°C (12,000°F)
  • Heat in the core is probably generated by the radioactive decay of uranium and other elements
  • Solid because of the pressure from the outer core, mantle, and crust compressing it tremendously
• Temperature increases as depth increases
• The lithosphere (crust and upper mantle) is divided into separate plates which move very slowly in response to the "convecting" part of the mantle

  
• The two images show that the layers of the Earth include the crust, mantle, and core, and that the lithosphere is divided into plates that move slowly