layers of the earth

• Standard


  S6E5a. Compare and contrast the Earth's crust, mantle, and core including temperature, density, and composition.
• Name the 4 main layers of the Earth

  • Crust
  • Mantle
  • Outer Core
  • Inner Core
• Basic Layers Percent of Earth's mass

  • Crust
  • Mantle
  • Core
• Crust


  Thinnest layer of the Earth, part of the lithosphere
• Crust


  • Made up of large amounts of SILICON AND ALUMINUM
  • Composed of plates on which the continents and oceans rest. These "ride" over molten mantle
  • Crust is part of the lithosphere
  • Two types of Crust: Oceanic and Continental
• Continental vs. Oceanic Crust

  • Continental
  • Oceanic
• Continental Crust


  • Rock Type: Granite
  • Thickness: 5 – 70km (Thicker)
  • State: Solid
  • Crust Age: 4 billion years old or Older
  • Density: Less Dense
  • Element Composition: Oxygen, Sodium, Silicon, Aluminum, Potassium
• Oceanic Crust


  • Rock Type: Basalt
  • Thickness: 3 – 8 km (Thinner)
  • State: Solid
  • Crust Age: 180 million years old or Younger
  • Density: More Dense
  • Element Composition: Iron, Magnesium, Calcium
• Lithosphere


  The crust and the upper layer of the mantle together make up a zone of rigid, brittle rock called the Lithosphere.
• Lithosphere


  The lithosphere (crust and upper mantle) is divided into separate plates which move very slowly in response to the "convection" part of the mantle.
• Lithospheric Plates


  The crust of the Earth is broken into many pieces called plates. The plates "float" on the soft, semi-rigid asthenosphere.
• Mantle


  • Upper Mantle
  • Lower Mantle
  • Middle Mantle
• Mantle


  The Mantle is the largest layer of the Earth at 2900 km thick. The middle mantle is composed of very hot dense rock that flows like asphalt under a heavy weight. The movement of the middle mantle (asthenosphere) is the reason that the crustal plates of the Earth move.
• Asthenosphere


  The asthenosphere is the semi-rigid part of the middle mantle that flows like hot asphalt under a heavy weight.
• Convection Currents


  The middle mantle "flows" because of convection currents. Convection currents are caused by the very hot material at the deepest part of the mantle rising being less dense, then cooling becoming more dense and sinking again --repeating this cycle over and over.
• Mantle


  • Solid but capable of flow (like fudge)
  • Semi-Solid/Semi Liquid
  • Thickest layer of the Earth 2900km (1800 miles)
  • Element Composition: Magnesium, Silicon, Oxygen, and Iron
  • The hot magma rises then cools and sinks
  • These convection currents cause changes in the Earth's surface
  • Conveyor belt for the tectonic plates
• Mantle


  • Upper Mantle
  • Convection Currents
  • Middle Mantle
  • Lower Mantle
• Core


  • Inner Core
  • Outer Core
• Outer Core


  • Composition: Molten (liquid) metal that is about 4,700°C (8,500°F)
  • Thickness: 2,266 km (1,400) miles
  • State of Matter: Composed of the melted metals nickel and iron (liquid)
  • Located about 1,800 miles beneath the crust.
• Inner Core


  • Solid sphere made mostly of iron and has Nickel
  • It is believed to be as hot as 6,650°C (12,000°F)
  • Heat in the core generated by the radioactive decay of uranium and other elements
  • It is solid because of the pressure from the outer core, mantle, and crust compressing it.
  • Thickness: 1271 km (800 miles)
• Temperature increases as depth increases
• Depth


  Density and Pressure increase as depth increases
• Scientists have drilled 7.6 miles into the earth, which is only 0.2% of the distance to the earth's core
• How do we know so much about what's under Earth's surface?

  Through INDIRECT EVIDENCE, mostly from seismic waves caused by earthquakes. Sometimes indirect evidence is the only option for scientists to develop a theory
• Big Ideas


  • The Earth is divided into 3 Main Layers: Crust, Mantle, Core
  • Main Rock type of the 2 types of Crust: Oceanic - Basalt, Continental - Granite
  • Oceanic Crust is denser than Continental Crust
  • The lithosphere is divided into tectonic plates
  • The Mantle has the convection currents which causes the plates to move
  • The Asthenosphere flows semi-liquid on which the plates move
  • Temperature, pressure, and density increases as depth increases. This is a direct relationship.