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Earth science 9th grade

STUDY
PLAY
plates:
sections of Earth's litosphere that is composed of crust and upper mantle (continental and oceanic plates)
plate techtonics
theory that crust and upper mantle move on plastic like layer of the mantle.
lithosphere:
ocean crust, continental crust, rigid upper mantle (about 100 km thick)
*asthenosphere:
plastic-like layer beneath the lithosphere
outer core:
liquid, mostly iron
inner core:
solid, dense, mostly iron and some nickel
continental drift
hypothesis that continents moved slowly to their current locations (Alfred Wegener, 1912)
pangaea:
single large land mass made up of all continents connected that broke apart 200 million years ago
seafloor spreading:
theory that magma moving upward spreads seafloor apart at mid ocean
convection current:
cycle of heating, rising, cooling, sinking that makes plates move
subduction zone:
area where one plate sinks below another; most dense plate sinks
convergent boundaries:
area where two plates move towards each other
divergent boundaries:
area where two plates move away from eachother
PLATE BOUNDARY
zone where many volcanos & earthquakes occur
MID-OCEAN RIDGE
a diverging boundary marked by a rift valley
FAULT
a crack or break in Earth's crust
TERRANE
block of lithoshere moved thousands of kilometers and attached to the edge of a continent