Friday, March 2, 2012

Divergent Boundries

Let's look at divergent plate boundaries:
  • mid-ocean ridges (pictures on left )- this is also known as seafloor spreading. At these boundaries new ocean crust is formed at an average rate rate of 5 cm per year. As one moves away from these ridges the crust cools, becomes denser and is older. As the seafloor spreads the age of the sediments that are on the ocean floor also increases. The top picture on left is a diagram of magnetic reversals. As the seafloor spreads and cools the magnetic rock particles align themselves with the magnetic poles of the earth. These reversals provide evidence for seafloor spreading.
  • continental divergent boundaries (picture on right)- the Red Sea is an example of continental divergent boundaries. This is when a land mass splits apart.
  • In both these examples magma pushes up through the lithosphere, volcanoes and volcanic activity is a product of these types of boundaries.

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