Theory of Plate Tectonics Theory that pieces of

Theory of Plate Tectonics • Theory that pieces of lithosphere move around on top of the asthenosphere

Plate Boundaries • The edges of different pieces of The lithosphere meet at lines called plate boundaries

Plate Boundaries Plate Videos

So the plates move. Now What? • As the plates move, they produce changes in Earth’s surface, including volcanoes, earthquakes, mountain ranges, and deepocean trenches.

3 Types of Plate Boundaries Divergent Convergent Transform Divergent

3 Types of Boundaries Divergent boundary= two plates move apart • Magma rises and creates new crust or seafloor Causes: midocean ridges, rift valleys, new crust , volcanoes

Divergent Boundaries © All Rights Reserved. Diverging Africa

Diverging Iceland

3 Types of Boundaries • Convergent= when two tectonic plates push into one another.

Convergent Boundaries • Continental vs. Continental • Continental vs. Oceanic • Oceanic vs. Oceanic

Continental vs. Continental • When two continental crustal plates collide, the continents buckle upward and form mountains. Himalayas- Asia

Himalayas- Asia

Oceanic vs. Continental • The oceanic plate slides under the continental plate. • The continental crust crumbles and forms new mountains.

Oceanic vs. Continental • Ex: Andes mtn in S. America Cascade Mtns. in N. America- Mt. St. Helens

Oceanic vs. Oceanic • Two oceanic plates collide, one of the oceanic plates slides under the other. • also called a subduction zone

Oceanic vs. Oceanic Hawaiian Islands

Transform boundary • When two tectonic plates slide past each other horizontally Produces? Earthquakes

San Andreas Fault

New Madrid Fault

How do the plates move? • CONVECTION CURRENTS • Hot material rises while cooler material near the surface sinks • Convection example

How do the plates move? • CONVECTION CURRENTS • Hot material from deep within the Earth rises while cooler material near the surface sinks

Convection currents

How do we know? • Sea-floor spreading =new ocean floor is created as two lithospheric plates pull away from one another.

Seafloor spreading

The Plates Move… So what now? Which way? • 50 million years