Earth’s internal composition and Landforms — Social Science STD 7 — Question

Sometimes due to internal pressure, there are great movements in the semi-liquid matters of the magma in the interior of the earth.

• The water which percolates in the interior is transformed into water vapour due to internal heat.
• The vapour occupies more space than the water.
• So it exerts tremendous pressure on all sides.

Due to such reasons, the land explodes where the rocks are soft.

• Vapour, ash, rock fragments, mud and thereafter the hot magma-lava are thrown out.
• This magma-lava cools down and spreads on all sides and forms sloppy, coneshaped mountain. This is called a 'Volcanic mountain'. Thus, a volcano is formed.