Convection Currents, Plate Tectonics

Divergent

Plates pull apart and magma rises up.

Transform

Plates slide past each other

Alfred Wegener

Proposed the continental drift theory in the 1900s

When rock material is heated by Earth's core, will it rise or sink?

Rise

When rock material is cool towards the top of the mantle, will it rise or sink?

Sink

trench

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

rift valley

long, narrow depression formed at divergent boundaries

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.

San Andreas Fault

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

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.

volcano

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

Convergent

Equally dense plates collide and make mountains or If plates are different densities, subduction occurs, one plate slides under the other.

North American Plate

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

Transform Boundary

The boundary between tectonic plates that are sliding past each other horizontally

Divergent Boundary

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

Convergent Boundary

The boundary formed by the collision of two plates

Continental Drift

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

mantle

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

Mariana Trench

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

Convection

The movement caused within a fluid by the tendency of less dense material to rise and denser material to sink

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

Sea-floor spreading

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

What causes the movement of crustal plates?

The rising and sinking of material in the mantle.

Asthenosphere

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

Lithosphere

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

Plate Tectonics

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

Crust

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

Plate Tectonics

Theory that the Earth's crust is divided into tectonic plates which move around due to convection currents in the mantle.

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

mid-ocean ridge

an underwater mountain range made at divergent plate boundaries

subduction

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

Pangea

term for the super continent which contained all the plates together

oceanic crust

thinner, more dense, younger crust making ocean floor