THEORY OF PLATE TECTONICS

THEORY OF PLATE TECTONICS

REVIEW OF REVIEW OF CONTINENTAL DRIFTCONTINENTAL DRIFT

REVIEW OF REVIEW OF CONTINENTAL DRIFTCONTINENTAL DRIFT

Continental Drift: All continents once connected into one supercontinent called Pangaea

Pangaea broke apart & continents drifted to present locations

Continental Drift: All continents once connected into one supercontinent called Pangaea

Pangaea broke apart & continents drifted to present locations

FROM CONTINENTAL DRIFT FROM CONTINENTAL DRIFT TO PLATE TECTONICSTO PLATE TECTONICS

FROM CONTINENTAL DRIFT FROM CONTINENTAL DRIFT TO PLATE TECTONICSTO PLATE TECTONICS

Problem with Continental Drift –

•Age of Earth: Earth too young for processes to occur

•No direct evidence of continents actually moving

•No known force could move continents

Problem with Continental Drift –

•Age of Earth: Earth too young for processes to occur

•No direct evidence of continents actually moving

•No known force could move continents

WWII brought new technology & new evidence!!•Age of EarthSONAR: Exploration of ocean floor showed seafloor very old & new crust forming

•No direct evidenceGPS: Measured movement of continents

•No known force:Convection currents in Earth powerful enough to move plates

WWII brought new technology & new evidence!!•Age of EarthSONAR: Exploration of ocean floor showed seafloor very old & new crust forming

•No direct evidenceGPS: Measured movement of continents

•No known force:Convection currents in Earth powerful enough to move plates Alvin: Navy's remote robot probe

FROM CONTINENTAL DRIFT FROM CONTINENTAL DRIFT TO PLATE TECTONICSTO PLATE TECTONICS

FROM CONTINENTAL DRIFT FROM CONTINENTAL DRIFT TO PLATE TECTONICSTO PLATE TECTONICS

NEW THEORY : NEW THEORY : PLATE TECTONICSPLATE TECTONICS

NEW THEORY : NEW THEORY : PLATE TECTONICSPLATE TECTONICS

Continental Drift + convection currents theory of plate tectonics

Theory of plate tectonics:

Earth is made of rigid lithospheric plates moved byconvection currents

Convection currents are heat currents insidethe mantel

Continental Drift + convection currents theory of plate tectonics

Theory of plate tectonics:

Earth is made of rigid lithospheric plates moved byconvection currents

Convection currents are heat currents insidethe mantel

LITHOSPHERIC PLATESLITHOSPHERIC PLATES

The lithosphere (crust + upper mantle) is made of rigid pieces

Lithosphere 7 large, 7 small plates

Plates “float” on the asthenosphere(liquid part of the upper mantle)

Plate Tectonics is the mechanismfor Continental Drift.

The lithosphere (crust + upper mantle) is made of rigid pieces

Lithosphere 7 large, 7 small plates

Plates “float” on the asthenosphere(liquid part of the upper mantle)

Plate Tectonics is the mechanismfor Continental Drift.

CONVECTION CURRENTSCONVECTION CURRENTS

Convection Currents = currents of rock & heat formed by temperature difference between core & mantle

Core transfers heat to the mantle where hot rock & heat rise;

Convection currents in asthenosphere move lithospheric plates

Movement between plates causes landforms & earthquakes

Convection Currents = currents of rock & heat formed by temperature difference between core & mantle

Core transfers heat to the mantle where hot rock & heat rise;

Convection currents in asthenosphere move lithospheric plates

Movement between plates causes landforms & earthquakes

Continent:continent

PLATES MOVE THREE WAYSPLATES MOVE THREE WAYSPLATES MOVE THREE WAYSPLATES MOVE THREE WAYS

At the edges of plates, convection currents cause 3 types of boundaries:

•Divergent boundary plates move AWAY from each other

•Convergent boundaryplates move TOWARDS each other

•Transform boundaryplates move SIDEWAYS to each other

At the edges of plates, convection currents cause 3 types of boundaries:

•Divergent boundary plates move AWAY from each other

•Convergent boundaryplates move TOWARDS each other

•Transform boundaryplates move SIDEWAYS to each other

Ocean: continent

Sea Floor Spreading

PLATES + CURRENTS =PLATES + CURRENTS =NEW LAND FORMSNEW LAND FORMS

PLATES + CURRENTS =PLATES + CURRENTS =NEW LAND FORMSNEW LAND FORMS

• Divergent boundary Ocean:Ocean → mid-ocean ridges

Continent:Continent → rift valleys

• Convergent boundaryOcean: (Ocean or Continent) → subduction zones, trenches & volcanoes

Continent:Continent → folded mountains

• Divergent boundary Ocean:Ocean → mid-ocean ridges

Continent:Continent → rift valleys

• Convergent boundaryOcean: (Ocean or Continent) → subduction zones, trenches & volcanoes

Continent:Continent → folded mountains

PLATES + CURRENTS =PLATES + CURRENTS =EARTHQUAKESEARTHQUAKES

PLATES + CURRENTS =PLATES + CURRENTS =EARTHQUAKESEARTHQUAKES

• Transform boundaries

Do not create new landforms

• Transform boundaries

Do not create new landforms