Essential Question: Explain why Earth’s plates move Plate Tectonics Essential Question: Explain why Earth’s plates move

Earth’s Interior

The Mantle What makes the mantle flow? Convection Currents

Oceanic and Continental Crust

The Crust Outer layer 5-100 km thick 2 types of crust Oceanic (very dense, made of basalt) Continental (less dense, made of granite)

Earth’s Layers How are the earth’s layers similar to an egg? Shell=crust Egg white=mantle Yolk=core

Earth’s Plates The uppermost rigid layer of mantle moves as if it were part of Earth’s crust. The rigid upper part of Earth’s mantle and crust is called the lithosphere.

Tectonic Plates Earth’s crust is broken into about 30 pieces These plates move on top of the plastic-like part of the mantle. Video 8, 10(Ice Age), 9

Tectonic Plates The places where the edges of different plates meet are called plate boundaries.

Plate Boundaries Where the boundaries meet the forces are large enough to cause: Mountains Volcanoes Faults

Plate Boundaries Faults: Large fractures in which movement occurs. Can cause earthquakes.

Plate Movement Plates that move apart from each other create new crust. Gaps are filled in by magma. These areas are called rift valleys. Video 11,12

Plate Movement When plates move toward each other, they collide. When two continental plates collide the crust piles up. This can create mountains. Video: Formation of Mountains 13

Plate Movement When an oceanic plate collides with another oceanic plate or a continental plate, the more dense one plunges underneath the other forming a trench. When one plate sinks underneath another plate, its called subduction. Video 14

Plate Movement Plates can also slide past on another. The picture shows the San Andreas Fault in California.

Plate Movement Question: Where does this energy come from? It takes a tremendous amount of force to move plates. Question: Where does this energy come from?

Plate Movement Gravity In the mantle; density differences