Continental Drift and Plate Tectonics (copy)

tectonic plate

a massive, irregularly shaped slab of lithosphere usually composed of both oceanic and continental lithosphere; AKA lithospheric plate

lithosphere

outermost layer of the Earth containing the crust and uppermost rigid part of the mantle

asthenosphere

"plastic" or putty-like layer directly underneath the lithosphere; plates ride on this layer

continental drift

idea proposed by Alfred Wegener that the continents move; explained why the same fossils and rock formations were found on now widely-separated continents

oceanic crust

crust underneath the oceans; thinner and more dense than continental crust

continental crust

crust making up the continents; thicker and less dense than oceanic crust

magnetic reversal

a change in Earth's magnetic field such that the positions of magnetic north and magnetic south are interchanged

seafloor spreading

process that occurs at mid-ocean ridges where new oceanic crust is formed through volcanic activity and then gradually moves away from the ridge

Theory of Plate Tectonics

scientific theory that explains how volcano formation, earthquakes, mountain formation, and the changing positions of continents is caused by the movements of lithospheric plates

subduction

process where one tectonic plate moves under another tectonic plate and sinks into the mantle as they converge

subduction zone

a boundary where two plates converge, and because of differences in density, one dives beneath the other

slab pull

the pulling action exerted by the sinking (subducted) edge of a plate on the rest of the plate

convection

heat transfer by the motion of a fluid away from the heat source

deep-ocean trench

a long, narrow trench in oceanic crust usually lying above a subduction zone

mid-ocean ridge

underwater mountain chain formed as tectonic plates spread apart; wraps around the globe like the seam of a baseball

fault

a crack in the Earth's crust along which rocks have shifted

earthquake

what happens when two slabs of lithosphere suddenly slip past each other

volcano

a place where molten rock makes its way to the surface

lava

molten rock above the surface

magma

molten rock below the surface

Pangaea

a famous supercontinent that existed about 225 million years ago and has since broken up

supercontinent

a large landmass formed by the convergence of multiple continents

What type of boundary is this?

Convergent Plate Boundary (with subduction)

What type of plate boundary is this?

Divergent Plate Boundary (where two plates move apart)

What type of boundary is this?

Transform plate boundary (Plate move past each other)

What are the three types of Convergent plate boundaries?

Oceanic- Oceanic , Continental-Continental, Oceanic-Continental