Plate tectonics : Plate tectonics : chapter 9.3 & 9.4chapter 9.3 & 9.4

TemperaturTemperaturee

In core, 6000+ In core, 6000+ CC

Radioactive Radioactive elements, high elements, high pressure create pressure create the high tempsthe high temps

Convection Convection currentscurrents in the in the mantle move the mantle move the continentscontinents

Convection currents Convection currents Convection currents occur when a gas or a liquid is Convection currents occur when a gas or a liquid is

heated from the bottom.heated from the bottom. Warm gasses & liquids are Warm gasses & liquids are less denseless dense than cold. than cold. The warm substance rises and the cold sinks. The warm substance rises and the cold sinks. This process is responsible for air, ocean, & mantel This process is responsible for air, ocean, & mantel

currents. currents.

Pair share: look at the picture are the two oceanic plates moving towards or away from each other?

Plates move as they ‘float’ on a moving mantle

LithosphereLithosphere& &

AsthenosphAsthenosphereere

Made of the crust and the upper mantle- 60 miles Made of the crust and the upper mantle- 60 miles thick thick

Divided into 7 large Divided into 7 large tectonic platestectonic plates Continental driftContinental drift is the movement of the plates is the movement of the plates

over timeover time

Plate Plate boundarboundariesies

• DivergentDivergent : plates move : plates move apartapart• Magma comes up to fill the gap: Magma comes up to fill the gap:

volcanoes, rift valleys, new crust formedvolcanoes, rift valleys, new crust formed

Pair share: show your partner with your hands how divergent plates move.

Mid-Atlantic ridge: a divergent plate boundary

N and S America were separated from Europe, Africa

ConvergConvergent ent

boundarboundaryy

Plates move towards each otherPlates move towards each other subductionsubduction when the denser oceanic plate dives when the denser oceanic plate dives belowbelow

the continental plate. the continental plate. Forms ocean trenches, mountain ranges, and volcanoes.Forms ocean trenches, mountain ranges, and volcanoes. ex: Andes, Cascades mtns.ex: Andes, Cascades mtns.

Pair share: show your partner with your hands how convergent plates move.

Colliding continental crustsColliding continental crusts

Both plates push Both plates push upwardsupwards Indian plate smashes into the Asian plateIndian plate smashes into the Asian plate Himalayas form: world’s tallest mountainsHimalayas form: world’s tallest mountains

Mt. Everest

Transform Transform faultsfaults

2 plates 2 plates slide pastslide past each other.each other.

Pacific Plate slides Pacific Plate slides N past the North N past the North American plate American plate

San Andreas faultSan Andreas fault

Pair share: show your partner with your hands how transform faults move.

Review Review

1.Convection currents occur because warm liquids are _________ than cold liquids.

2.Divergent plates move ________ ______ each other.

3.Convergent plates move ______ _____ each other.