earth layers

Crust

The thin, outermost, solid layer of Earth.

Mantle

The thick layer of mostly solid rock beneath the crust, capable of slow flow.

Outer Core

The layer of liquid iron and nickel beneath the mantle, generating Earth's magnetic field.

Inner Core

The solid, dense center of Earth, composed mainly of iron and nickel.

Lithosphere

The rigid outer layer, composed of the crust and uppermost mantle (forms the tectonic plates).

Asthenosphere

The weak, plastic-like layer of the upper mantle below the lithosphere, allowing plates to move.

Continental Crust

Thicker, less dense crust that makes up the continents (granitic).

Oceanic Crust

Thinner, denser crust beneath the oceans (basaltic).

Magma

Molten rock material located beneath the Earth's surface.

Convection

The transfer of heat in the mantle where warm material rises and cool material sinks, driving plate motion.

Plate Tectonics

The theory that Earth's lithosphere is divided into plates that move relative to each other.

Continental Drift

The slow movement of continents over geologic time.

Divergent Boundary

Plates moving apart; new crust is formed.

Convergent Boundary

Plates moving toward each other; results in collision or subduction.

Transform Boundary

Plates sliding horizontally past each other.

Subduction Zone

A region where one plate sinks beneath another at a convergent boundary.

Earthquake

A sudden shaking of the ground caused by movement of rock along a fault.

Fault

A fracture in rock where displacement (movement) has occurred.

Igneous Rock

Rock formed from the cooling and solidification of magma or lava.

Metamorphic Rock

Rock changed by intense heat and pressure without complete melting.

P-wave (Primary Wave)

The fastest seismic wave, moves by compression, and travels through solids and liquids.

S-wave (Secondary Wave)

A slower seismic wave that moves rock side-to-side and can only travel through solids.