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Plate Tectonics
• Scientist, Tuzo Wilson, combined the knowledge of sea-floor
spreading, earths plates, and continental drift into a single
theory- The Theory of Plate Tectonics
• Theory of Plate Tectonics (PT) - pieces of Earth’s lithosphere
are in slow, constant motion, driven by convection currents in
the mantle.
• PT explains the formation, movement, and subduction of
Earth’s plates
Plate Boundaries
Types of boundaries:
1. Divergent- place where two plates move apart
o Most occur along mid-ocean ridges where sea-floor
spreading occurs
o On land, two plates slide apart creating a rift valley
o Can produce EQs
Examples:
Mid Atlantic Ridge
Iceland
Great Rift Valley (Africa)
2. Convergent- place where two plates come together or collide
o Ocean vs. continental- oceanic slides under
o Continental vs. continental- neither crust is dense enough
to sink so they squeeze the crust into mountain ranges.
o Oceanic vs. oceanic- plate that is more dense sinks
o
Convergent boundaries produce mountains, deep
ocean trenches, earthquakes, volcanoes.
Examples
Mariana Trench
Himalaya Mountains
Ring of Fire
3. Transform- two plates slip past each other,
moving in opposite directions.
o EQs often occur
o Crust isn’t created or destroyed
Example:
San Andreas Fault
http://viewpure.com/dkELENdZukI?start=0&end=0
Instructions: Repeat the words “convergent collide,
divergent divide, transform boundaries slide” while
mimicking the hand motions for each type of boundary.
Bozeman’s Plate Tectonics
https://www.youtube.com/watch?v=JmC-vjQGSNM