Plate tectonics | Glossary

Glossary

continental drift

the theory suggesting that the Earth’s crust is split up into large slabs called plates that slowly move along the Earth’s surface

plate tectonics

the theory suggesting that the Earth’s crust is split up into large slabs of solid rock called tectonic plates

Gondwanaland

the ancient supercontinent of the southern hemisphere

Pangaea

the supercontinent from around 300 million years ago

Mesosaurus

an extinct freshwater reptile

Glossopteris

a seed fern

magnetic anomalies

a stripy pattern in plates because of a variation in the Earth’s magnetic field/the reversal of the Earth’s poles

Benioff zone

a zone of earthquakes close to ocean trenches

outer core

a fluid layer of the Earth composed of mostly iron and nickel

inner core

the innermost layer of the Earth that is about 2414km thick

mantle

the mostly solid layer of the Earth between the core and the crust that is about 2900km thick

asthenosphere

the zone of the Earth’s mantle between the lithosphere that is hot and fluid

lithosphere

the rigid layer of the Earth made up of the crust and the solid outermost layer of the upper mantle

Moho (Mohorovicic discontinuity)

the boundary between the crust and the mantle of the Earth

crust

the outermost shell/layer of the planet

mid-ocean ridges

seafloor mountain systems

subduction zone

where oceanic crust sinks back into the mantle

viscosity

the resistance of a fluid to change shape/the thickness of a fluid

slab pull

the force that is generated from denser oceanic plates subducting beneath less dense continental plates at subduction zones

mantle plumes

a mechanism of convection within the Earth’s mantle