Earth's Interior

1
Earth's Interior
Summarize the three layers of Earth- crust,
mantle, core- on the basis of relative position,
density, and composition.
2

• Objectives
• 1.What do geologists do?
• What are the characteristics of Earth's crust,
  mantle, and core?
• geologists- scientists study forces that make and
  shape Earth.
• chemical/ physical makeup of rocks
• map location of types of rock on Earth
• describe landforms
• search for clues about Earth's history
• Earth looks very different today!

3

• Constructive forces- shape surface by building
  mountains
• Destructive forces- wear away mountains and
  landmasses (wind, water- ocean waves)
• 200 years ago- what geologists knew
• Earth is a sphere
• 6,000 km radius
• 7 continents
• made up of rock

4

• What's inside the Earth?
• deepest mine in the world 3.8 kilometers (6,000
  km to center of Earth)
• Indirect method to find out Earth's interior
• Seismic waves- waves of energy produces by
  Earthquakes.
• Geologists study
• 1. how the waves travel
• 2. speed of the seismic waves
• 3. paths that the waves take
• determined that Earth's interior is made up of
  many layers

5

• Journey to the Center of the Earth!
• Temperature
• surface rock cool, 20 meters down it is warmer
• After 40 meters decent, 1C increase
• Pressure- force per unit of area
• force pushing on a surface or area
• weight pressure of rock increases as descend

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• Crust, Mantle, Core
• Crust-
• "outer skin"
• 5 to 40 km thick
• Basalt- dark, dense rock under oceans, fine
  texture
• Granite- less dense continental rock, coarse
  texture

7

• Mantle-
• lithosphere- "lithos" Greek for stone
• layer of mantle that is solid rock
• 100 km thick
• asthenosphere- Greek for weak soft flowing rock
• rock bends like plastic due to high heat and
  pressure
• lithosphere floats on top of asthenosphere
• mantle is 3 000 km thick

8

• Core-
• outer core- molten iron and nickel, behaves like
  thick liquid
• inner core- extreme pressure forms solid iron and
  nickel
• inner and outer core slightly smaller than the
  moon! 1/3 Earth's mass
• Earth's Magnetic Field
• iron and nickel very magnetic- responsible for
  producing Earth's magnetic field

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Layer Position Density Composition
Crust Outermost layer, thinnest under the ocean, thickest under the continents crust and top of mantle called the lithosphere Least dense layer overall oceanic crustdense basalt, continental crustless dense granite Solid rock
Mantle Middle layer, thickest layer top portion called the lithosphere Density increases with depth because of increasing pressure Hot softened rock contains iron magnesium
Core Inner layer consists of two parts- outer core inner core Heaviest material most dense layer Mostly iron nickel outer core- slow flowing liquid, inner core- solid