Name ________________________________________
Earth and Space Science Course 320
Date ___________
Unit 2 Vocabulary – Plate Tectonics
crust – solid, rocky outer layer of Earth
mantle – solid middle region of Earth
inner core – solid iron/nickel center of Earth
outer core – liquid iron/nickel layer above the inner core
continental crust – the thicker part of the crust that makes up the continents and consists mainly of rocks
such as granite (low density, light color).
oceanic crust – the thinner part of the crust that makes up the ocean floor. It is made up of primarily basalt
(higher density, dark color).
lithosphere – the layer of Earth made up of the crust and upper mantle
asthenosphere – the plastic-like, but solid, layer in the mantle which allows the lithosphere above to move
continental drift hypothesis – the continents once formed a giant landmass (Pangaea), broke apart, and
then drifted to their current locations
mid-ocean ridge – a continuous mountain chain on the floor of all major ocean basins
seafloor spreading – process where the sea floor spreads apart along both sides of an oceanic ridge as new
crust forms from molten rock at the center.
subduction zone – an area where oceanic crust is forced down into the mantle beneath another plate
plate tectonics theory – changes in Earth’s crust, including the movement of continents, is caused by the
slow movement of large plates
plate – section of the lithosphere usually made up of both oceanic and continental crust
divergent boundary – plate boundary (edge) where two plates diverge, or move apart, and new crust or
lithosphere is formed
convergent boundary – plate boundary where two plates converge, or come together
transform fault boundary – plate boundary where two plates slide past one another with no creation or
destruction of lithosphere
hot spot -- stationary plumes of magma that rises up causing volcanic activity
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