Plate Tectonics

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Plate Tectonics

• Liz LaRosa for use with my 5th Grade Science
  Class http//www.middleschoolscience.com 2009

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Earths Layers
The Earth's rocky outer crust solidified billions
of years ago, soon after the Earth formed. This
crust is not a solid shell it is broken up into
huge, thick plates that drift atop the soft,
underlying mantle.
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The Crust

• Outermost layer
• 5 100 km thick
• Made of Oxygen, Silicon, Aluminum

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The Mantle

• Layer of Earth between the crust and the core
• Contains most of the Earths mass
• Has more magnesium and less aluminum and silicon
  than the crust
• Is denser than the crust

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The Core

• Below the mantle and to the center of the Earth
• Believed to be mostly Iron, smaller amounts of
  Nickel, almost no Oxygen, Silicon, Aluminum, or
  Magnesium

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Tectonic Plates
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Plate Tectonics

• Greek tektonikos of a builder
• 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
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Review

• Name the 3 main layers of the Earth
• What is a tectonic plate?
• What was Pangea?
• What is Sea-Floor spreading?
• Name the three different types of plate
  boundaries and one location on Earth for each one