Inside the Earth

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Inside the Earth
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Planet Earth

• All objects on or near Earth are
• pulled toward Earths center by
• gravity.
• Earth formed as gravity pulled small particles
  together, that would collide, build mass, and
  collect more particles.
• Early Earth generated thermal energy in its
  interior, making the rocks of the planet soft
  enough to flow.

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Formation of Earths Layers

• Earth developed distinct layers of different
  material according to their densities (Do you
  remember DENSITY?).
• When ancient Earth started melting, the densest
  materials sank and formed the innermost layer.
• The least dense materials stayed at the surface
  and formed a separate layer, and materials with
  intermediate densities formed layers in between.
  

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• Temperature and pressure increase as depth
  increases inside Earth.

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Composition (What it is made of)

• Core
• Mantle
• Crust

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Core

• -Outer core liquid iron nickel
• -Inner core solid iron nickel

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The Inner Core

• The inner core of the Earth has temperatures and
  pressures so great that the metals are squeezed
  together and are not able to move.
• The inner core is a solid.

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The Outer Core

• The outer core is liquid.
• The outer core is made up of iron and is very
  dense.
• Because the outer core contains iron, when it
  flows it generates a magnetic field. This is the
  source of the Earth's magnetic field.

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Mantle

• -Much thicker layer about 2,900 km
• -Contains most of Earths mass.
• -Molten rock
• -Magma comes from mantle

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The Mantle

• The mantle is the largest layer of the Earth.
• The mantle is divided into two regions the upper
  and lower sections.
• The upper mantle is a solid while the lower
  mantle is more fluid.

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Mantle cont.

• The layer of rocks within the mantle, where the
  rock is soft enough to flow, is called the
  asthenosphere.

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Convection Currents

• As the molten material in the asthenosphere is
  heated by the core it becomes less dense and
  rises.
• The material cools because it gets further away
  from the heat source. Because its cooler, its
  more dense so it sinks.
• Its now closer to the heat so it all begins
  again!

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The Crust

• Outer layer
• 5-100 km thick
• Makes up only 1 of Earths mass.
• 2 types of crust
• Oceanic (very dense, made of basalt)
• Continental (less dense, made of granite)

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Oceanic and Continental Crust

• The crust is typically about 25 miles thick
  beneath continents, and about 6.5 miles thick
  beneath oceans. The crust is relatively light and
  brittle. Most earthquakes occur within the crust.

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Physical Structure of the Earth(5 Layers)

• Lithosphere- rigid outer layer crust upper
  mantle
• Asthenosphere- solid rock that flows slowly (like
  hot asphalt)
• Mesosphere- middle layer
• Outer Core- liquid layer
• Inner Core- solid due to pressure, very dense

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Tectonic Plates

• Earths lithosphere is broken into about 19
  pieces
• These plates move on top of the asthenosphere due
  to convection currents.