plate tectonics what evidence do scientists have to support the fact that the earths crust is...

Plate TectonicsWhat 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– 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