Download PLATE BOUNDARIES

• http://ed.ted.com/lessons/the-pangaeapop-up-michael-molina
Earth’s Crust
• OCEANIC
• Denser, Basaltic, THINNER
Mafic – rich in Iron (Fe) and Magnesium
(Mg)
• CONTINENTAL
• Lighter, Granitic, THICKER
Felsic – rich in Aluminum (Al) and Silicon
(Si)
• ESRT page 10
The Crust
The crust is composed of two rocks. The
continental crust is mostly granite. The oceanic
crust is basalt. Basalt is much denser than the
granite. Because of this the less dense continents
ride on the denser oceanic plates.
PLATE BOUNDARIES
ESRT Page 5
1. DIVERGENT
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Plates move apart, magma rises up
New crust is formed, volcanoes
Results in
Mid-Ocean ridges and
Rift Valleys on continents
2. Transform
• Plates slide past one another
• Results in
- Faulting
- Ex. San Andreas Fault in California
2. CONVERGENT
• plates converge (move together)
• SUBDUCTION – more dense plate moves
under less dense
a. Oceanic vs. Continental Crust
(subduction)
• Oceanic (more dense) plate subducts
under continental (less dense) plate
• Results in
- Trenches
- volcanic chain along coast of continent
EX. Andes Mountains along South America
b. 2 Oceanic Plates
(subduction)
• More dense plate subducts under the less
dense oceanic plate
• Results in
- Trenches, volcanoes and volcanic
island chains
Ex. Aleutian Islands in Alaska
C. 2 Continental Plates
(compression)
• Plates collide
• Rocks break and build up
• Results In
- Mountain building
Ex. Himalayas
ESRT Page 5
2 CONVERGING PLATES
OVERRIDING PLATE
SUBDUCTING PLATE