DO NOW

• Take out last night’s homework – Continental Drift vs. Sea-Floor Spreading handout

• Turn to your neighbor and share your answers with your neighbor.

PLATE TECTONICS

Plate Tectonics• The idea that Earth’s surface is broken into

plates that slide slowly across the mantle• Mantle- the layer beneath the Earth’s crust

Tectonic Plates

Tectonic Plates

What causes the plates to move?• Convection currents caused by magma

The Lithosphere and Asthenosphere

• The crust and the layer of the upper mantle that form plates are called the lithosphere

• They rest on the upper mantle called the asthenosphere

• Earth has two kinds of crust: continental crust and oceanic crust– Continents are made of continental

crust, which is made up of rocks that are less dense than oceanic crust

– The ocean floor is made up of oceanic crust, which is made up of rocks that are more dense than continental crust

What is a plate boundary?

• Plate boundaries are where the edges of plates meet

• There are three types of plate boundaries• The type of boundary depends on whether

the plates are moving toward each other, separating, or sliding past each other

Three Types of Plate Boundaries

Plate Boundaries

Divergent Boundaries

• Divergent boundary- form where plates diverge, or move away from each other

- These boundaries are under oceans and build undersea mountain ranges called mid-ocean ridges

Divergent Boundaries

Convergent Boundaries

• Convergent boundary- form where plates collide -The pressure and violence at

convergent boundaries produces mountains, bands of volcanic activity, and deep ocean trenches

Convergent Boundaries• Oceanic and Continental Crust Convergent

Boundary

Convergent Boundaries• Continental and Continental Crust Convergent

Boundary

Convergent Boundaries• Oceanic and Oceanic Crust Convergent Boundary

Transform Fault Boundaries

• Transform fault boundary- form where two plates slide past each other - As plates smash and grind past

each other, there are many earthquakes

Transform Fault Boundaries