plate tectonics. the earth’s crust is made of plates

Plate TectonicsPlate Tectonics

The Earth’s Crust is Made of PlatesThe Earth’s Crust is Made of Plates

What Causes the Plates to Move?What Causes the Plates to Move?

• Convection- hot magma rises, cool magma sinks (like a lava lamp

Two Types of crustTwo Types of crust

• Continental Crust- made of granite (light)

• Oceanic Crust- made of basalt (heavy)

Plate BoundariesPlate Boundaries

• Cracks in the plates are called faults

Types of Boundaries (Faults)Types of Boundaries (Faults)

• Convergent Boundary• Divergent Boundary• Transform Boundary

Divergent BoundaryDivergent Boundary

• Plates move away from each other

• Forms volcanoes,

new crust and rift valleys

• Ex) Iceland, mid-Atlantic ridge

Divergent Boundary – Divergent Boundary – Arabian and African PlatesArabian and African Plates

Divergent Boundary – Divergent Boundary – IcelandIceland

http://pubs.usgs.gov/gip/dynamic/understanding.html

Rift ValleysRift Valleys

• A deep valley formed as plates move apart at a divergent boundary.

• Ex) The Great Rift Valley in eastern Africa

Sea Floor SpreadingSea Floor Spreading

• Mid Ocean Ridges – underwater mountain chains that run through the Earth’s Basins

• Magma rises to the surface and solidifies and new crust forms

• Older Crust is pushed

farther away from the ridge

Transform BoundaryTransform Boundary

• Plates slide past each other

• Creates earthquakes

• Ex) San Andreas Fault in California

Convergent BoundaryConvergent Boundary

• Plates move toward each other

• Earthquakes, forms mountain ranges

• Ex) Himalayan Mountains

Continental-Continental BoundaryContinental-Continental Boundary

• Plates fold, creating mountains

Convergent Boundaries - ContinentalConvergent Boundaries - Continental

http://pubs.usgs.gov/gip/dynamic/understanding.html & http://www.geology.com

Oceanic-Oceanic BoundaryOceanic-Oceanic Boundary• Creates trenches (deep valleys)• Forms volcanoes• Forms Island Arcs • Ex) Aleutian Islands (Alaska)

Convergent Boundary – Oceanic & OceanicConvergent Boundary – Oceanic & Oceanic

http://pubs.usgs.gov/gip/dynamic/understanding.html & http://www.geology.com

Subduction occurs when the denser plate sinks below the other

Oceanic-Continental BoundaryOceanic-Continental Boundary• Oceanic plate pushes

down because it is more dense.

• Creates deep ocean trenches

• Creates coastal mountain ranges

• Ex) Andes mountains

Convergent Boundary – Oceanic & ContinentalConvergent Boundary – Oceanic & Continental

http://pubs.usgs.gov/gip/dynamic/understanding.html & http://www.geology.com

Hot SpotsHot Spots

• Hot material rises from deep within the mantle.

• Heats the lithosphere, causing volcanoes at the surface.

• Ex) Hawaiian Islands, Yellowstone N.P.

Evidence of PangaeaEvidence of Pangaea

Vocab to RememberVocab to Remember

• Fault

• Convection

• Divergent Boundary

• Convergent Boundary

Vocab ctd…Vocab ctd…

• Transform Boundary

• Rift Valley

• Hot Spot