Volcanic Activity: Intrusive, Extrusive

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  • Created by: Sarah
  • Created on: 24-01-15 15:03

Volcanic activity can be intrusive and Extrusive:

  1. The high pressure inside the Earth keeps rocks in some parts of the Mantle semi-molten
  2. When this pressure is released the rocks become molten
  3. Due to the magma being less dense than the rock it rises
  4. Most magma doesnt reach the surface, but some can.

Intrusive volcanic activity:

  • Takes place beneath the surface
  • Large magma chambers; dykes, sills and batholiths


  1. When large chambers of magma cool beneath the surface they form domes of igneous rock called batholiths.
  2. When magma has flowed into gaps and it cools verticaly it forms dykes, if it cools horizontaly - sills
  3. Cracks may form as magama cools, this is…


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