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A review set for the Earth Science Plate Tectonics Unit.

Theory of Continental Drift

Theory that continents move due to centrifical force

Theory of Plate Tectonics

Theory that plates that move due to convection currents

Alfred Wegener

credited with the theory of Continental Drift

Harry Hess

credited with the theory of Plate Tectonics

sea floor spreading

when two oceanic plates pull apart, magma rises and new crust is formed

convection currents

circular movement of a substance due to changes in temperature and density


large pieces of earths crust that move due to convection currents

oceanic crust

earths crust located under the ocean

continental crust

earths crust made of land


large supercontinent that existed 250 million years ago

divergent boundary

when two plates pull apart

convergent boundary

when two plates come together

transform boundary

when two plates grind past each other

rift valley

formed when two plates pull apart and land falls downard

island arc

a chain of volcanic islands formed at an ocean-ocean convergent boundary

volcanic arc

a chain of volcanic mountains formed at an ocean-continental convergent boundary

mountain range

formed at a continental-continental convergent boundary

subduction zone

the more dense plate us pulled into the mantle under the less dense plate

Mid Atlantic Ridge

divergent boundary in the middle of the Atlantic Ocean


depression formed at a subduction zone


another name for the crust


another name for them mantle


outer layer of the Earth, the thinnest layer


thickest layer of the Earth, part liquid part solid where convection currents are found

mountain range

form at continental-continental convergent boundaries

temperature inside Earth

increases with depth

pressure inside Earth

increases with depth


a break in the earths crust that moves

igneous rock

formed from cooling lava

hot spot

area where magma from the mantle continually breaks through the crust

hot spot example

Hawaiian islands

age of ocean rocks

younger near sea floor spreading zone

high risk cities

cities where earthquakes and volcanoes are likely to happen

low risk cities

cities where earthquakes and volcanoes are not likely to happen

plate tectonics evidence

rocks, fossils, climate, puzzle fit, glaciers, sea floor spreading

rate of plate movement

5 cm/year

rock crystals

form when rocks cool slowly

crust density

ocean crust is more dense

Wegener's evidence

fossils, rocks, climate

Wegener's flaws

how continents moved

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