The Layers of the Earth

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The Layers of the Earth
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Earth Layers

• The Earth is divided into 4 main layers.
• Inner Core
• Outer Core
• Mantle
• Crust

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The Crust

• Outermost layer of the Earth
• The Earths crust is like the skin of an apple.
  It is very thin compared to the other three
  layers.
• The crust makes up 1 of the Earth and is called
  the rock and mineral layer.
• The crust of the Earth is broken into many pieces
  called plates.
• At the junction of these plates some interesting
  things occur!

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Plate Tectonics
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Sea-Floor Spreading
Volcanoes
Earthquakes
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And what type of crust would you like with your
Earth?

• There are two types of crust.
• Continental crust
• Oceanic crust

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Continental Crust

• Makes up the continents
• Contains light colored rocks such as granite.
• Floats high on the mantle

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Oceanic Crust

• Makes up the ocean floor
• Contains the dense rocks such as basalt
• Thinner than the continental crust

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The Mantle

• The mantle is the layer between the crust and the
  outer core.
• The mantle is the largest layer of the Earth.
• The mantle is made up of MAGMA (hot molten rock).
• Because of the heating and cooling of liquid
  rock, convection currents occur. These currents
  force the plates of the crust to move.

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Mantle Zones Lithosphere

• Thin, uppermost part of the mantle and crust
  rigid, brittle rock
• Floats on the athenosphere, and slides around
  very slowly.
• The upper part of the lithosphere melts rocks,
  forming a substance called magma.

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Magma

• Magma (melted rock) moves like hot oatmeal.
• Uneven heating causes material in the mantle to
  constantly and slowly rise fall in convection
  currents.
• Convection Currents process by which hot fluid
  rises to the surface, and then sinks again, like
  soup being heated in a saucepan

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CONVECTION IN THE MANTLE
CRUST
MANTLE
COOL LIQUID SINKS
HOT LIQUID RISES
OUTER CORE
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Mantle Zones Asthenosphere

• Hot, weak zone directly under the lithosphere
• Flows at a very slow rate like hot asphalt under
  a heavy weight
• The movement (convection currents) of the
  asthenosphere is the reason that the crustal
  plates of the Earth move

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Core

• Deep within the Earth is the core
• The core is made mostly of nickel iron
• Twice as dense as the mantle.
• Main source of heat that triggers the convection
  currents
• The core is made of two layers

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Outer Core

• The outer core of the Earth is a ball of very hot
  liquid metal.
• The outer core is made up of mostly iron and is
  very dense.
• Because this liquid metal is moving, positive and
  negative particles are created and released that
  create the Earths MAGNETIC FIELD.

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Magnetic Field
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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.
• Therefore the inner core is a solid.
• The temperature in the core is nearly as hot as
  the surface of the SUN!

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Plate Tectonics

• Pieces of the lithosphere that move around
• Each plate has a name
• Fit together like jigsaw puzzles
• Float on top of mantle similar to ice cubes in a
  bowl of water

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Continental Drift
Alfred Wegener 1900s Continents were once a
single land mass that drifted apart. Fossils of
the same plants and animals are found on
different continents Called this supercontinent
Pangea, Greek for all Earth 245 Million years
ago Split again Laurasia Gondwana 180
million years ago
http//members.enchantedlearning.com/subjects/astr
onomy/planets/earth/Continents.shtml
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Evidence of Pangea
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Sea Floor Spreading
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Sea Floor Spreading

• Mid Ocean Ridges underwater mountain chains
  that run through the Earths Basins
• Magma rises to the
• surface and solidifies
• and new crust forms
• Older Crust is pushed
• farther away from the
• ridge

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How Plates Move
http//pubs.usgs.gov/gip/dynamic/unanswered.html
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Different Types of Boundaries
http//pubs.usgs.gov/gip/dynamic/understanding.htm
l
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Divergent Boundary Arabian and African Plates
Arabian Plate
Red Sea
African Plate
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Divergent Boundary Iceland
http//pubs.usgs.gov/gip/dynamic/understanding.htm
l
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Divergent Boundary - Oceanic
http//www.geology.com
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Divergent Boundary - Continental
http//www.geology.com
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Convergent Boundary Indian and Eurasian Plates
Eurasian Plate
Indian Plate
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Convergent Boundary Oceanic Continental
http//pubs.usgs.gov/gip/dynamic/understanding.htm
l http//www.geology.com
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Convergent Boundary Oceanic Oceanic
Note plates are reversed
http//pubs.usgs.gov/gip/dynamic/understanding.htm
l http//www.geology.com
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Convergent Boundaries - Continental
http//pubs.usgs.gov/gip/dynamic/understanding.htm
l http//www.geology.com
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Transform Boundary San Andreas Fault
www.geology.com