Plate Tectonics What evidence do scientists have to support the fact that the Earth’s crust is continuously moving?

Plate Tectonics The theory that describes how tectonic plates move and shape Earth’s surface Tectonic plates are huge pieces of crust that fit together at their edges to cover Earth’s surface.

About 12 plates exist on Earth

Earth’s Interior Crust – Rigid outer shell of Earth Mantle Oceanic and Continental Crust Mantle Upper mantle is partially molten Lower mantle is rigid (solid)

Earth’s Interior Core Outer core is molten iron, source of Earth’s magnetic field Inner core is solid, Iron and Nickel

Plate Boundaries Divergent Boundary Convergent Boundary Transform Boundary

Divergent Boundary Two tectonic plates move apart from each other Rift valleys – long narrow depressions Rift valley in East Africa

Convergent Boundary Two tectonic plates move towards each other (come together) Oceanic Plates are more dense Continental Plates are less dense

Subduction Process when one tectonic plate slips beneath another plate

Oceanic – Oceanic Subduction Occurs Deep Sea Trenches (Marianas Trench)

Oceanic – Continental Subduction Occurs Trench and Volcanic Arch (Peru – Chile Trench)

Continental – Continental Mountain Building Himalayas Aleutian Islands

Transform Boundary Region where two plates slide past each other Earthquakes occur at transform boundaries San Andreas Fault in San Francisco

San Andreas Fault