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