Volcanoes are mountains where lava, that is, hot, liquid rock, comes from a magma chamber under the ground where pressure causes it to blow off the top of the solid rock, and then the magma pours out.
3 Additional Answers
Volcanoes are formed when magma found inside the upper mantle of the Earth forces its way to the surface. When it reaches the surface, it erupts forming ash deposits and lava flows. The volcano will get bigger as it continues to erupt.
There are many different kinds of volcanoes namely: shield, cinder cone and composite. All volcanoes are made of gas and magma. The magma turns into lava at the earth's surface. The lava cools to make a hill and this happens many times to form a hill or mountain shape.
Volcanoes are made out of solidified lava, ash and cinder, which are released during one or several eruptions. All volcanoes start as holes in the ground and grow over time.