Asthenosphere

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The partially melted layer of the mantle that underlies the lithoshere.

Body Waves

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Seismic waves are waves that travel through the Earth or other elastic body, for example as the result of an earthquake, explosion, or some other process that imparts forces to the body.

Craton

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The ancient core of a contenent, usually the oldest and most altered rocks of the continent.

Convection Currents

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The movement of heat by currents within a heated material.

Deep-Focus Earthquake

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A deep-focus earthquake is an earthquake that occurs at depths between 300 and 700 km beneath the Earth's surface.

Earthquake

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The shaking of Earth's crust caused by a sudden release of energy.

Epicenter

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Point  on Earht's surface directly above the focus of an earthquake.

Fault

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Abreak or crack in Earth's crust along which movement has occured.

Focus

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A point within Earth at which an earthquake originates.

Hot Spots

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Areas of cocanic activity near the center of lithospheric plates.

Lithosphere

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The lithosphere includes the curst and the uppermost mantle which is joined to the crust across the mantle. The lithosphere is underlain by the asthenosphere, the weaker, hotter, and deeper part of the upper mantle.

Mantle Convection

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Mantle Convection is the slow creeping motion of Earth's rocky mantle in response to perpetual gravitationally unstable variations in its density.

Pangaea

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Pangaea was the supercontinent that existed during the Paleozoic and Mesozoic eras about 250 million years ago, before the component continents were separated into their current configuration.

Primary Waves

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P-waves are type of elastic wave, also called seismic waves, that can travel through gasses, elastic solids and liquids, including the Earth.

Ridge Push

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Ridge-push is a proposed mechanism for plate motion in plate tectonics.

Secondary Waves

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S-waves: is one of the two main types of elastic body waves, so named because they move through the body of an object, unlike surface waves.

Seismic Waves

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Seismic waves are waves that travel through the Earth or other elastic body, for example as the result of an earthquake, explosion, or some other process that imparts forces to the body.

Shallow-Focus Earthquake

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An earthquake whose focus is located within 70 kilometers of the earth's surface.

Slab Pull

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As a crustal plate moves further from an oceanic ridge, it cools and becomes increasingly dense. This causes it to sink beneath the continental crust in a subduction zone. The weight of this sinking, cooling plate causes a major pulling action, which causes the rest of the plate to be pulled downwards as well.

Surface Waves

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A surface wave is a mechanical wave that propagates along the interface between differing media, usually two fluids with different densities.

Terrane

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A terrane in geology is a fragment of crustal material formed on, or broken off from, one tectonic plate and accreted — "satured" — to crust lying on another plate.

Thin-Skinned Thrusting

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The pushing of then, horizontal sheets of rock from continental margins over great distances along nearly level fault surfaces.

Volcanic Belt

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A volcanic belt is a large volcanically active region.

Volcanic Island Arc

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A volcanic arc is a chain of volcanic islands or mountains formed by plate techtonics as an oceanic volcanic plate subducts under another tectonic plate and produces magma.

Volcano

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A volcano is an opening, or rupture, in a planet's surface or crust, which allows hot, molten rock, ash, and gases to escape from below the surface.