9. landforms - plate tectonics.ppt

Plate tectonicsPlate tectonics

PlatesPlates – sections of crust which are – sections of crust which are in motion they are either moving in motion they are either moving apart or collidingapart or colliding

Plate boundariesPlate boundaries – are the areas – are the areas where the plates meetwhere the plates meet

CrustCrust – the thin shell of the planet – the thin shell of the planet which supports lifewhich supports life

Reunite PangaeaReunite Pangaea

Plate tectonicsPlate tectonics

ConvectionConvection – deep within the earths – deep within the earths surface (2900km) lies a very hot surface (2900km) lies a very hot semi-liquid rock semi-liquid rock

This molten rock moves upward This molten rock moves upward constantly like when you are boiling constantly like when you are boiling something on the stove and the something on the stove and the contents circulate upwardscontents circulate upwards

The pressure from this action called The pressure from this action called convection sometimes results in convection sometimes results in cracks in the cracks in the platesplates

Like an eggshellLike an eggshell

Continental DriftContinental Drift

The theory of The theory of continental drift was continental drift was proposed in 1912 by proposed in 1912 by Alfred WegenerAlfred Wegener

Before this the Before this the earth’s surface was earth’s surface was thought to be rigidthought to be rigid

He named the He named the original super-island original super-island PangaeaPangaea

Major PlatesMajor Plates

African African American American AntarcticAntarctic EurasianEurasian Pacific (ring of fire)Pacific (ring of fire) IndianIndian NazcaNazca

Divergent plate boundaryDivergent plate boundary

A boundary between tectonic plates in A boundary between tectonic plates in which the two plates move away from which the two plates move away from each other, and new crust is created each other, and new crust is created between thembetween them

The Hawaiian islesThe Hawaiian isles

Convergent plate boundaryConvergent plate boundary

A boundary between tectonic plates in A boundary between tectonic plates in which the two plates move toward one which the two plates move toward one another, destroying or thickening the crustanother, destroying or thickening the crust

Plate boundariesPlate boundaries Continental platesContinental plates are lighter than are lighter than

oceanic plates oceanic plates When these plates collide the lighter When these plates collide the lighter

continental platescontinental plates travel over the travel over the heavier oceanic plates heavier oceanic plates

When plates meet they often buckle and When plates meet they often buckle and produce fold mountains, this is how the produce fold mountains, this is how the Western Cordillera was formed Western Cordillera was formed

When a heavier (oceanic) plate sinks When a heavier (oceanic) plate sinks beneath a lighter continental plate it may beneath a lighter continental plate it may begin to melt which forces hot magma to begin to melt which forces hot magma to the surface (convection) the surface (convection)

This process can result in volcanic activityThis process can result in volcanic activity

EarthquakesEarthquakes

Earthquakes occur when there is a Earthquakes occur when there is a pressure release between tectonic pressure release between tectonic platesplates

This can occur on the surface or This can occur on the surface or underwaterunderwater

On land – Los AngelesOn land – Los Angeles Underwater – Indian OceanUnderwater – Indian Ocean

In Canada earthquakes In Canada earthquakes are monitored by The are monitored by The Geological Survey of Geological Survey of CanadaCanada

They keep data on all They keep data on all earthquake activity in earthquake activity in and around Canadaand around Canada

Most earthquakes are Most earthquakes are not detectable by not detectable by humanshumans

Earthquakes in CanadaEarthquakes in Canada

Tsunami’sTsunami’s

Tsunami’sTsunami’s Tsunami is a word of Japanese originTsunami is a word of Japanese origin It means large waveIt means large wave The large wave is triggered by an The large wave is triggered by an

underwater earthquakeunderwater earthquake This earthquake sends an energy This earthquake sends an energy

wave along the surface of the waterwave along the surface of the water The wave travels at about 800 km/hThe wave travels at about 800 km/h Once the wave hits shallower water it Once the wave hits shallower water it

rises up and becomes a danger for rises up and becomes a danger for anyone in its pathanyone in its path

Earthquake detectionEarthquake detection Most earthquakes are too small for Most earthquakes are too small for

people to feel and require a people to feel and require a seismographseismograph to be detected to be detected

Seismographs record Seismographs record seismic seismic waveswaves or vibrations or vibrations

Earthquake intensity is measured on Earthquake intensity is measured on a 10 point scale called the a 10 point scale called the Richter Richter ScaleScale

This system was developed by This system was developed by Charles F. Richter in 1935Charles F. Richter in 1935

Seismographs past and Seismographs past and presentpresent

seismologyseismology

Data is collected to research the Data is collected to research the magnitude and frequency of earth magnitude and frequency of earth quakesquakes

Data is collected to try to predict Data is collected to try to predict future earthquakesfuture earthquakes

HomeworkHomework

Textbook: 88-93Textbook: 88-93 Questions: 1,2,3,4,5Questions: 1,2,3,4,5