The Effects of Plate Tectonics

1
The Effects of Plate Tectonics
2
What Is Plate Tectonics

• On the inside of the Earth there is a sea of
  molten magma.
• Continental plates float on the sea.
• The plates are always in motion as they drift
  along.
• Pangaea separated long ago to the place the
  continents are now.

3
Rifts and Trenches

• In the oceans are rifts where magma comes from
  inside the Earth.
• Rifts are found where two plates come together.
• The rising magma pushes the ocean plates apart.
• Trenches are places where the ocean plates slip
  under the continental plates.
• As the upper part of the plate moves outward
  toward the trench, the lower part moves back
  toward the rift.
• The process of making the new plate and getting
  rid of the old is called Subduction.

4
Oceanic Plate Movement
5
Mountains of Fire

• Most volcanoes are located along rifts or faults
  where plates come together.
• Pressure builds up from heat and pressure of
  plates.
• Pressure is released eventually as an eruption,
  throwing magma in the air and sending lava
  flowing.
• There are four types of volcanoes.
• Cinder cones are made from mostly volcanic ash.
• Composites are made from alternating layers of
  ash and pyroclastic flows (lava).
• Shield volcanoes are very big and broad formed
  mainly from pyroclastic flows.
• Lava domes are bubbles of hardened lava with
  liquid magma centers.
• Here are some PDF files about volcanoes.

6
Fault Stress Earthquake

• Two continental plates come together at a fault
  and begin to push on each other
• Over time (usually several years), the plates
  build up pressure against each other.
• Eventually, so much pressure builds up that the
  plates buckle or slip past each other. This is
  an earthquake.

7
Types of Faults

• (A) is known as a transform fault or slip fault
  since the plates slip past each other. More on
  transform faults here.
• (B) is a divergent fault. The plates here move
  apart or diverge from each other. More on
  divergent faults here.
• (C) is a convergent fault. Its plates come
  together until one goes under the other one.
  More on convergent faults here

8
Summary

• Giant plates under the continents
• Pangaea broke up due to continental drift.
• Rifts and trenches in the ocean floor where new
  and old sea floor is made and destroyed
  (Subduction)
• Plates come together at faults.
• Four types of volcanoes occur at faults and
  rifts.
• Earthquakes happen when too much stress is put on
  a fault which is then released.
• There are three types of faults where earthquakes
  occur.