Download Plate Tectonic Theory

Plate Tectonic Theory
• Theory of Plate Tectonics -Earth’s crust is
broken into plates which float and move.
Earth’s crust made of many plates is similar to
the shapes on a outside of a soccer ball.
There are about 13 plates covering
Earth’s surface
Two Types of Plates
• Continental Plates – lighter, thicker, made of
granite
• Oceanic Plates – heavier, thinner, made of
basalt
Plate Boundaries (edges)
When the plates move, their
boundaries, or edges, can scrape each
other or collide.
Convergent Boundary
• Plates move toward each other
Convergent Boundary
• When two continental plates move into each other, the
plates combine and form mountains. (India into Asia)
http://www.absorblearning.c
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http://www.classzone.com/books/earth_science/terc/content/visualizations/es1105/es1105page01.cfm?chapter_no=visualization
Convergent Boundary
• When an oceanic plate runs into a continental
plate, the heavier oceanic plate subducts
(sinks) into the mantle and melts back into
magma.
• Volcanic mountains and deep sea trenches are
created along this edge.
http://www.
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Oceanic plate into continental
• Example: Pacific plate (oceanic) subducts (sinks) under
Japan (continental).
http://maps.google.com/
Divergent Boundary
• Plates move apart
When both diverging plates are oceanic,
it is called seafloor spreading
(Mid-Atlantic Ridge)
When both diverging plates are
continental it is called rift valley
formation (Africa)
http://highered.mcgrawhill.com/olcweb/cgi/pluginpop.cgi?it=swf::640::480::/sites/dl/free/0072402466/30425/19_21.swf::Fig.%2019.21%
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Transform Boundary
• Plates slide past each other
San Andreas Fault
San Andreas Fault, CA
• Each time the plates slide past each other, an earthquake
occurs
Find the three boundaries
http://www.pbs.org/wgbh/aso/tryit/tectonics/shockwave.html
Asthenosphere
• A plastic-like layer found below the lithosphere.
• The rigid oceanic and continental plates of the
lithosphere sit on top
The Asthenosphere is heated by the hot Outer
Core
Convection Current
crust
mantle
core
• Hot material rises, cooler material sinks,
creating a current, called a Convection
Current
When the asthenosphere moves, it carries the
lithospheric plates
Convection currents cause plate motion
https://www.youtube.com/watch?v=ryrXAGY1dmE
http://www.absorblearning.com/media/attachment.action?quick=12p&att=2775
Every time these plates move we get earthquakes,
volcanic eruptions, and possibly tsunamis