Igneous rocks

  • Igneous rocks(Rock types) are formed when the original molten material solidified.
  • On the basis of mode of formation igneous rocks are of two types.

1)Plutonic rocks: these are originally formed inside the earth by the solidification of the magma and pushed to the surface by various earth movements in pre-geological periods. Cooling inside the earth was a slow process and hence crystal formed during cooling. This the reason for the crystalline nature of Plutonic rocks. Examples of Plutonic rocks are Diorite, Granite, Syenite, Gabbro.

2)Volcanic rocks: these are formed on the surface of the earth by the cooling and solidification of lava. Cooling on the surface was a rapid process and rocks formed are glassy in structure. Examples of Volcanic rocks are Andesite, trachyte, and basalt. Basalt is prominent in the Deccan trap area.

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