Plate Tectonics. Benjamin Franklin in 1782 wrote The crust of the earth must be a float on a liquid interior Thus the surface of the globe would be.

Plate TectonicsPlate Tectonics

Benjamin Franklin in 1782 wroteBenjamin Franklin in 1782 wrote

The crust of the earth The crust of the earth must be a float on a must be a float on a liquid interiorliquid interior

Thus the surface of the Thus the surface of the globe would be globe would be capable of being capable of being broken by the violent broken by the violent fluid on which it rests.fluid on which it rests.

Plate Tectonic TheoryPlate Tectonic Theory

Plate Tectonic theory Plate Tectonic theory helped to explain the helped to explain the formation of the earth’s formation of the earth’s plates and continental plates and continental driftdrift

Plate ExamplePlate Example

Take a hard-boiled egg and Take a hard-boiled egg and crack its shell. crack its shell.

The egg could be seen as a tiny The egg could be seen as a tiny model of the Earth. The thin model of the Earth. The thin shell represents the Earth's shell represents the Earth's crust, divided into plates; within crust, divided into plates; within the shell is the firm but slippery the shell is the firm but slippery mantle. mantle.

Plate Tectonic TheoryPlate Tectonic Theory

Plate tectonic theory Plate tectonic theory states that pieces of states that pieces of Earth’s lithosphere, Earth’s lithosphere, called plates, move called plates, move about slowly on top of about slowly on top of the asthenospherethe asthenosphere

The Force to move a Continent The Force to move a Continent

Convection is the process Convection is the process that moves Continental that moves Continental PlatesPlates

As heat moves outward As heat moves outward from the earth’s interior, from the earth’s interior, convection currents rise in convection currents rise in the mantlethe mantle

These currents spread out These currents spread out beneath the lithosphere, beneath the lithosphere, dragging plates with themdragging plates with them

The Force to move a Continent The Force to move a Continent

As the rock cools, it sinks back to the bottom of the As the rock cools, it sinks back to the bottom of the mantle, reheats and floats up againmantle, reheats and floats up again

Sea Floor SpreadingSea Floor Spreading

Sea Floor Spreading takes Sea Floor Spreading takes place at the boundary of the place at the boundary of the oceanic plates oceanic plates

As Convection pulls plates As Convection pulls plates apart magma rises up threw apart magma rises up threw new cracks.new cracks.

Magma piles up and solidifies, Magma piles up and solidifies, slowly forming a long chain of slowly forming a long chain of mountains on the ocean floor, mountains on the ocean floor, called an oceanic ridge. called an oceanic ridge.

This new rock land moves This new rock land moves plates farther apart.plates farther apart.

There are basically two types There are basically two types of plates. of plates.

Oceanic plates Oceanic plates

Continental platesContinental plates

What Are Oceanic Plates? What Are Oceanic Plates?

Oceanic plates, as the Oceanic plates, as the name goes, are crusts name goes, are crusts which 'carry' the oceans which 'carry' the oceans above it.above it.

It is made of lighter but It is made of lighter but denser materials than the denser materials than the continental crust.continental crust.

This explains why they This explains why they tend to subduct, or sink tend to subduct, or sink under continental crust under continental crust when the two collide due to when the two collide due to plate tectonicsplate tectonics

What Are Continental What Are Continental Plates? Plates?

Continental plates are crust Continental plates are crust that have continents (Large that have continents (Large land masses) and some land masses) and some areas of ocean on them.areas of ocean on them.

They are usually named They are usually named after the continents they after the continents they 'carry'.'carry'.

Because they are made of Because they are made of lighter and less dense lighter and less dense substances, they normally substances, they normally do not subduct. do not subduct.

What is Subduction?What is Subduction?

Just like cars on a Just like cars on a roadroad

The earth’s plates The earth’s plates sometimes have sometimes have accidentsaccidents

CRASH SITE

What is Subduction?What is Subduction?

Subduction is the sliding of one plate under another.

Three Types Of Plate Three Types Of Plate MovementsMovements

ConvergentConvergent DivergentDivergent TransformTransform

Convergent Plate Movement Convergent Plate Movement

When two plates move When two plates move towards each other, towards each other, they would collide. they would collide. This is called a This is called a convergent plate convergent plate movement. movement.

When A Continental And When A Continental And Oceanic Plate Collide Oceanic Plate Collide

When a continental plate and When a continental plate and an oceanic plate collide, The an oceanic plate collide, The impact of the collision also impact of the collision also causes cracks to form in the causes cracks to form in the crust. crust.

The heat and pressure from the The heat and pressure from the mantle forces the acidic mantle forces the acidic magma to rise up these cracks.magma to rise up these cracks.

As the magma continues to rise As the magma continues to rise up the cracks, it escapes onto up the cracks, it escapes onto the surface and solidifies, the surface and solidifies, building up a volcano. building up a volcano.

Transform Plate Movement Transform Plate Movement

A transform plate movement is one A transform plate movement is one where two plates slide laterally where two plates slide laterally past each other. past each other.

However, movement is not smooth However, movement is not smooth due to friction between the rocks of due to friction between the rocks of the two plates. the two plates.

Tension and pressure is built up at Tension and pressure is built up at the transform boundary. the transform boundary.

When there is sufficient buildup of When there is sufficient buildup of pressure, rocks in the plates break pressure, rocks in the plates break and get jerked apart. This results and get jerked apart. This results in earthquakesin earthquakes

Divergent Plate Movement Divergent Plate Movement

A divergent plate A divergent plate movement occurs movement occurs when two plates move when two plates move away from each other. away from each other. Magma from the Magma from the mantle underneath the mantle underneath the crust to rise up the crust to rise up the surface to cool and surface to cool and solidify at the plate solidify at the plate boundary. boundary.

Mid Ocean ShelfMid Ocean Shelf

When you go When you go swimming in a lake, swimming in a lake, you expect the you expect the middle to be the middle to be the deepest partdeepest part

Not in the oceanNot in the ocean Deep drop offs just Deep drop offs just

of shore called of shore called ocean shelfocean shelf

Mid Ocean RidgeMid Ocean Ridge

A chain of under water A chain of under water mountains and mountains and Volcanoes just off the Volcanoes just off the ocean shoreocean shore

Mountain BuildingMountain Building

Fold mountains, such Fold mountains, such as the Appalachian as the Appalachian Mountains in the Mountains in the eastern United States, eastern United States, and the Swiss Alps in and the Swiss Alps in Switzerland, form when Switzerland, form when two plates collide head two plates collide head on, and their edges on, and their edges crumblecrumble

The ResultThe Result

Sea floor spreading is Sea floor spreading is force that moves the force that moves the earth’s platesearth’s plates

Carrying along with Carrying along with them the continents them the continents giving use the force giving use the force required to complete required to complete continental drift theory.continental drift theory.