9. landforms - plate tectonics.ppt
TRANSCRIPT
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