The interior of the earth is extremely hot.
Due to high temperature deep inside the earth rocks turn into molten magma.
When this molten rock material is ejected to the earth’s surface during a volcanic eruption, it accumulates around the vent and may take the form of a cone.
With each eruption, the height of the cone rises and it assumes the shape of a mountain.
Since these mountains are formed by the accumulation of volcanic material, they are termed as volcanic mountains.
Examples of the mountains:
Mount Mauna Loa in Hawaii Islands
Mount Popa in Myanmar
Vesuvius in Italy
Cotopaxi in Ecuador
Fuji Yama in Japan