Moving PlatesMoving Plates

The Earth’s crust is composed of The Earth’s crust is composed of several huge, solid sections, called several huge, solid sections, called plates.plates.

These plates move slowly as they These plates move slowly as they float on the semi-liquid below.float on the semi-liquid below.

There are 7 major lithospheric plates:There are 7 major lithospheric plates: Indian-AustralianIndian-Australian PacificPacific North American North American South AmericanSouth American AntarcticAntarctic AfricanAfrican Eurasian.Eurasian.

There are 8 minor lithospheric plates:There are 8 minor lithospheric plates: Antarctic Plate (although some consider this to Antarctic Plate (although some consider this to

be a major plate!)be a major plate!) Arabian PlateArabian Plate Caribbean PlateCaribbean Plate Cocus PlateCocus Plate Juan de Fuca PlateJuan de Fuca Plate Nasco PlateNasco Plate Indian PlateIndian Plate Philippine PlatePhilippine Plate

Movement of PlatesMovement of Plates

The plates are moving relative to one The plates are moving relative to one another.another.

For example the plates that carry North For example the plates that carry North America and the plate that carries Europe America and the plate that carries Europe are moving away from each other.are moving away from each other.

Wherever plates meet, earthquakes signal Wherever plates meet, earthquakes signal their movement.their movement.

Most Earthquakes occur at the edge Most Earthquakes occur at the edge of continental and oceanic plates.of continental and oceanic plates.

Many of the Earth’s earthquakes Many of the Earth’s earthquakes occur in the Pacific Ocean around the occur in the Pacific Ocean around the “Ring of Fire”“Ring of Fire”

Mid Atlantic RidgeMid Atlantic Ridge

The The Mid-Atlantic Ridge (MAR)Mid-Atlantic Ridge (MAR) is a mid is a mid ocean ridge, a divergent tectonic plate ocean ridge, a divergent tectonic plate boundary located along the floor of the boundary located along the floor of the Atlantic Ocean.Atlantic Ocean.

It separates the It separates the Eurasian PlateEurasian Plate and and North American PlateNorth American Plate in the North Atlantic, in the North Atlantic, and the and the African PlateAfrican Plate from the from the South American PlateSouth American Plate in the South Atlantic. in the South Atlantic.

Slipping By: A FaultSlipping By: A Fault

A fault occurs in a place on the A fault occurs in a place on the Earth’s crust where plates are Earth’s crust where plates are slipping past each other.slipping past each other.

Collision: SubductionCollision: Subduction

Plates collide as they move toward Plates collide as they move toward each other.each other.

When they collide one plate slides When they collide one plate slides below the other. As the lower plate below the other. As the lower plate plunges underneath it pushes into plunges underneath it pushes into the hot mantle, heats up and melts.the hot mantle, heats up and melts.

Separation: RidgesSeparation: Ridges

In the places where the plates are In the places where the plates are moving apart from one another, hot moving apart from one another, hot magma rises up into the crack magma rises up into the crack between the plates and hardens, between the plates and hardens, forming forming ridgesridges of new rock. of new rock.