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Aflred Wegner

_____proposed theory of continental drift in 1912


super-continent name


One piece of evidence that supports Wegner, all continents look like they fit together like a ________


Evidence 2-different continents have the same_____from plants and animals


rocks from different continents have the same glacial_____

composition, age

rocks on different continents are similar in ____, ______


possible explanation by Wegner was Earth's ________

Weather man

occupation of Wegner


mid-atlantic ridge was discovered by mistake using______

Harry Hess

proposed theory of seafloor spreading in '60s

continental drift

theory that all continents were once connected but have drifted apart

seafloor spreading

theory that hot, less dense material below crust rises to surface at ridge; then flowing sideways carrying sea in both directions

Youngest, oldest

_________ rocks are closest to ridge, _________ are furthest away(age, age)

Magnetic clues

manetic field change ( reversal is recorded in rocks around ridge)


ridge splits this country in 1/2

plate tectonics

combines continental drift and seafloor spreading , crust is broken up into plates move on plastic layer of astenosphere


Plates move apart


plates move together


plates slide past

convection currents

cause magma to rise and cool at surface, causing a current that moves plates


occur at all boundaries


Underwater EQs


occur at subduction zones, divergent underwater


form at convergent boundaries

Deep sea trenches

form at convergent and push down into mantle

Rift valley

occur when plates pull apart

Oceanic Crust

type of crust that that is more dense than continental

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