Inner core
A ball of hot, solid metals at Earth's center
Outer core
A layer of liquid metals that surrounds Earth's inner core
Mantle
Earth's thickest layer, found between outer core and crust
Crust
The thin layer of rock that surrounds Earth
Lithosphere
Earth's crust and very top of the mantle combined
Asthenosphere
The layer of hotter, softer rock in the upper mantle, under the lithosphere
Tectonic Plate
One of the slabs of rock that Earth's lithosphere is broken up into
Continental Drift
The hypothesis that Earth's continents were once joined together but have gradually moved apart
Pangaea
The huge supercontinent that once included all of the landmasses on Earth; proposed by Alfred Wegener
Mid-ocean ridge
A long line of sea-floor mountains where new crust forms
Convection
The transfer of heat within a material
Convection Current
A motion where material is heated and rises in one area, then cools and sinks in another
Theory of Plate Tectonics
The theory that Earth's lithosphere is broken into huge, moving slabs of rock and is driven by motions in the mantle
Divergent Boundary
A boundary where 2 tectonic plates move apart
Convergent Boundary
A boundary where 2 tectonic plates push together
Transform Boundary
A boundary where 2 tectonic plates scrape past each other
Rift valley
The gap that forms where tectonic plates move apart
Magnetic Reversal
A switch in the direction of Earth's magnetic field where the magnetic north pole becomes the magnetic south pole
Hot spot
An area of volcanic activity because hot material rises from deep in the mantle
Subduction
The process where an oceanic tectonic plate sinks under another plate
Continental-continental collision
Where 2 continental plates collide, forms mountains
Oceanic-oceanic collision
Where the older oceanic crust sinks under the younger oceanic crust
Oceanic-continental collision
Where oceanic crust sinks under a plate with continental crust