1. Plates separate or collide and magma rises up through a gap called a vent.
  2. The magma reaches the surface cools and hardens . This is called lava.
  3. After many eruptions  many layers of lava creates  a cones shaped mountain. 
  4. The top of the volcano where lava flows out is called the crater.

Types of volcano. 

Active - erupted  in the past 10,000 years ( Mt .Helen's USA).

Dormant - has not erupted in the past 10,000 years but may erupt again ( kilimanjaro Tanzia).

Extinct - never expected to erupt again.(Mount Kenya, Kenya).