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 layers above the fault move down.
Rift valleys are forme when Earth's crust separates.

Examples of faults are ranges of mountains are seen.
Examples of rift valleys is the GReat Rift Valley in
africa.

The mid Atlantic Ridge is an example of mid ocean rides

Mountains are formed when two plates collide

A strike slip fault is where faults occur when two plate stick and then slip one by one.

Moutains

Volcanoes

The San Andreas Fault