Download Plate Tectonics

Plate Tectonics
Spectra of Science
Amole
2013
Continental Drift
• Proposed by Alfred
Wegener in 1915.
• Supercontinent
Pangaea started to
break up
about 200 million
years ago.
• Continents "drifted" to
their present positions.
Evidence
• Some continents
coastlines seem to
“fit” together
• Fossils match across
oceans
• Rock types and
structures match
across oceans
• Ancient glacial
features
Evidence
Evidence
Plate Tectonics
In 1965, J. Wilson
Earth’s lithosphere is
broken into sections
called plates.
Plates are always
shifting and moving.
Movement is driven
by convection
currents in the
mantle.
Earth’s Layers
The Plates
Types of Plate Boundaries
• Convergent
– Push
together
• Divergent
– Pull apart
• Transform
– Slide past
one
another
Convergent Boundaries
Oceanic- Continental
Oceanic is denser and sinks below continental
Creates a subduction zone
Creates trenches, volcanic mountain arc
Mt. St. Helens, Washington
Convergent Boundaries
Oceanic- Oceanic
Oceanic being of equal densities both “sink”
Creates a subduction zone
Creates trenches, island arc
Japanese Islands- Island Arc
Convergent Boundaries
Continental- Continental
Continentals being of equal densities both
“push up”
Creates folded mountains
Himalayas, Asia
Divergent Boundaries
Plates move away from
each other
Create gaps that new
magma rises through
making new crust
Cause of sea-floor
spreading
Creates rift valleys and
the Mid-Oceanic Ridge
Transform Boundaries
Plates slide past each other
Creates earthquakes
San Andres Fault, CA
Animations
• http://www.seed.slb.com/flash/science/featu
res/earth/livingplanet/plate_boundaries/en/i
ndex.html?width=570&height=475&popup=t
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