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