3.1 Earth's Interior

Crust

The outermost layer of Earth, divided into two types: the thinner, denser oceanic crust (basaltic) under the oceans and the thicker, less dense continental crust (granitic) that forms the continents

Asthenosphere

A solid, thin layer of mantle material below the lithosphere and above the liquid middle mantle or mesosphere.

Mantle

The thickest layer of Earth between the crust and the outer core, composed mostly of silicate rocks that can be semi-solid and/or flow slowly and makes up approximately 82% of Earth’s volume.

Mesosphere

The strong, lower liquid part of the mantle located beneath the asthenosphere and above the outer core, characterized by high pressure and temperature.

Core

The innermost layer of the Earth, composed mostly of iron and nickel, and divided into two parts.

Seismic wave

A type of wave generated by earthquakes that travels through the Earth's layers and used to study the Earth's interior structure, composition and state of matter.

Composition

The makeup of Earth's layers, including minerals and elements that define their structure and properties.

Physical Property

Describes the observable characteristics of something.

Outer Core

The liquid layer of Earth's interior located beneath the mantle and above the inner core, primarily composed of iron and nickel.

Inner Core

The solid innermost layer of Earth's interior, primarily composed of iron and nickel, and under extreme pressure and temperature.

Earthquake

A movement of the ground (tectonic plates) that happens when rocks break and move, typically along a fault line.

Seismograph

An instrument used to detect and record the vibrations caused by seismic waves resulting from earthquakes.

S waves

A type of seismic wave (Secondary Waves), can travel only through solid materials, are slower than P-waves and cause vertical ground motion.

P waves

A type of seismic wave (Primary Wave), can travel through solids and liquids, and are faster than S waves.

Subduction

the sideways and downward movement of the edge of a plate of the earth's crust into the mantle beneath another plate.

Plate tectonics

A theory stating that the earth's surface is broken into plates that move.

Theory

A hypothesis that has been tested with a significant amount of data

Sea floor Spreading

The process by which molten material adds new oceanic crust to the ocean floor

Magnetic Reversal

an event that causes a magnetic field to reverse direction, and is evidence for sea-floor spreading

Convection Current

a current caused by the rising of heated fluid and sinking of cooled fluid

Lithosphere

the rigid outer layer of the Earth, including the crust and upper mantle, involved in tectonic activity.

Asthenosphere

the semi-fluid layer of the Earth's mantle located beneath the lithosphere and above the middle mantle (mesosphere) that is responsible for the movement of tectonic plates.

Tectonic plate

A massive slab of solid rock that makes up the Earth's lithosphere and moves over the semi-fluid asthenosphere, leading to geological activity such as earthquakes and volcanic eruptions.

Epicenter

the point on the Earth that is straight above the middle of an earthquake