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 EQ s Examples: Mid Atlantic Ridge Iceland Great Rift Valley (Africa)

Examples Mariana Trench Himalaya Mountains Ring of Fire 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.

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

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