Plate Tectonics

Plate Tectonics

The theory that the earth is broken into plates and are in motion due to convection currents in the asthenosphere (upper mantle)

Alfred Wegener

Proposed the continental drift theory in the 1900s

Pangaea

term for the super continent which contained all the plates together

Crust

The thin and solid outermost layer of the Earth above the mantle

Lithosphere

The solid, outer layer of the Earth that consists of the the crust and the rigid upper part of the mantle

Asthenosphere

The soft layer of the mantle on which the tectonic plates move

Transform Boundary

The boundary between tectonic plates that are sliding past each other horizontally. Can cause earthquakes.

Continental Drift

The hypothesis that states that the continents once formed a single landmass, broke up, and drifted to their present locations

Sea-floor spreading

The process by which new oceanic crust forms as magma rises towards the surface and solidifies at divergeny boundaries. Oceanic-Oceanic divergence

Convergent Boundary

The boundary formed by the collision of two plates

Divergent Boundary

The boundary between two tectonic plates that are moving away from each other

rift valley

long, narrow depression formed at divergent boundaries, continental-continental

subduction

process in which two plates collide and the denser ocean plate descends below the other

convection current

a current caused by the rising of heated fluid and sinking of cooled fluid believed to drive plate movement in the mantle of the earth

trench

extremely deep areas in the ocean that are created by an oceanic subducting plate

ocean basin

areas that are below sea level

hot spot

an area in the mantle that is super heated and melts through the crust (like a blow-torch)

mid-ocean ridge

an underwater mountain range made at divergent plate boundaries Oceanic-Oceanic

dormant volcano

Inactive, sleeping

extinct volcano

A volcano that has not erupted for thousands of years and probably will not erupt again.

seismographs

measures and records earthquake magnitude based on the energy released in an earthquake.

tsunami

A giant wave usually caused by an earthquake beneath the ocean floor.

epicenter

The location on the surface directly above the focus

volcano

A weak spot in the crust where magma has come to the surface

earthquake

A shaking or sliding of the ground. It is caused by the sudden movement of masses of rock along a fault or by changes in the size and shape of masses of rock far beneath the earth's surface.

continental crust

The portion of the earth's crust that primarily contains granite, is less dense than oceanic crust, and is 20-50 km thick

oceanic crust

thinner, more dense, younger crust making ocean floor

mantle

The layer of hot, solid material between Earth's crust and core. The thickest layer.

North American Plate

Lithospheric plate that includes almost all of North America and part of the Atlantic Ocean.

Andes Mountains

A large system of mountain ranges located along the Pacific coast of South America formed above the subduction zone of two convverging plates. Oceanic-Continental

Mariana Trench

The location of the deepest trench on earth made from two oceanic crusts converging.

San Andreas Fault

A major geological fault in California formed by a sliding transform boundary.

Himalaya Mountains

A mountain range formed where continental & continental crust converges. Eurasia & Indian plates