Plate Tectonic

Theory(contintal Drift)

• Pangea is a theor one big landmass.
• This Theory is discovered by Alfred Wegner.
• He discovered that South America and Africa had similar fossils.
• Glossopteris is a plant fossil that is found in Africa, Australia, Asia, Soutn america, and Antarctic.
• The climates fossils of warm weather plants on Spitsbergen in the Artic Ocean.

Seafloor Spreading

• A rope method was used to discorver how to used sound waves to located subnarines.
• Now we used sound waves on ships.
• A mid ocean ridge are when chain of ridges ans valleys are stretching along Earth's ocean floor.
• The theory of seafloor spreading is magma or melted rock is forced up toward the surface at the midocean ridge.
• Rocks taken from the mid ocean ridge. New life forms have been discorved near the mid ocean ridge.

Contunue

• A madnetic field has a north ans a south pole.
• Iron in rocks records the magnetic reversal.

Pangea

Plate Tectonics

• Plates are large sections of crust and the upper mantle.
• Lithospere - the crust and rigid upper mantle. Asthenosphere- plasic like stubstance.

Lithosphere and asthenosphere

Plate Boundaries

• Divergent- when to plates move apart from each other. New seafloor spreading and rift valleys are formed here.
• Converegent- two plates come together. Mountains form here

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• Subduction zone- oceanic plates subduct. Volcanoes form here
• When oceanic plates collide the denser plate sinks down into mantle.

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• When continental plates collide, they fold and become mountain ranges.

Oceanic plate converge

Untitled Slide

Continetal collide

Transform

• Two plates slide past each other.
• Earthquakes occur in transform boundaries.

Causes of Plate Tectonics

Normal faults are formed when rocks layer above the fault move down .
Rifts are formed when Earth's crust sepa