Plate Tectonics

Plate Tectonics Theory

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

Alfred Wegener

The man who proposed the continental drift theory in the 1900s

Pangea

The name for the super continent which contained all the continental plates together

Lithosphere

The thin and solid outermost layer of the Earth above 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

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

Convergent Boundary

The boundary formed by the collision of two plates moving towards each other

Divergent Boundary

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

Rift valley

A long, narrow depression formed at divergent boundaries on land

Subduction

Process in which two plates collide and the denser ocean plate sinks below the other

Convection current

This flow of material in a fluid caused by movement of heat, and is believed to drive motion of the plates

Trench

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

Ocean basin

Areas that are below sea level and typically filled with deep water

Dormant volcano

Inactive or "sleeping" volcano that is not erupting

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.

Magma

Molten rock beneath the earth's surface

Convergent

Continental - Continental

Features: mountain ranges, mountains

Example: Himalayas

Convergent

Oceanic - Oceanic

Features: Trenches, volcanoes, volcanic islands

Examples: Japanese Islands, Ring of Fire

Convergent

Oceanic - Continental

Features: Volcanic Mountain Range on the coast, Trenches

Example: Andes Mountains

Volcano

A mountain or hill, typically cone-shaped, having a crater or vent through which lava, rock fragments, hot vapor, and gas erupted from the earth's crust.

Tectonic Plate

A block of lithosphere that consists of the crust and the rigid, outermost part of the mantle. It moves over time due to convection in the asthenosphere.

Oceanic Plate/Crust

Thin plates that form the ocean floor; more dense than continental plates.

Continental Plate/Crust

Thick plates that form the continents; less dense than oceanic plates

Tsunami

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

Hot Spot

An area far from a plate boundary where superheated magma from deep within the mantle melts through the crust above it. Ex: Hawaii, Yellowstone Supervolcano

Divergent Continent-Continent

Features: Rift valley, small volcanic vents, lakes

Example: Iceland, Great African Rift

Divergent Ocean-Ocean

Features: Mid-ocean ridge, underwater volcanoes

Example: Mid-Atlantic Ridge

Transform Boundary

Features: Major earthquakes, fault line, ridge or low mountains

Example: San Andrean Fault