Such openings can melt rocks that are in the earth's crust. Volcanos are a type of mountain that are cone shaped. Mountains themselves, are called volcanoes. Some eruptions form huge clouds that rise over the mountains. In other eruptions hot ash and cinders shoot on the mountain tops.
Some eruptions are so powerful it can blow a mountain apart.
Most eruptions are on volcanic islands. Such islands are on top of volcanic mountains. Other eruptions occur on the ocean surface. A volcano begins as magma. That is melted rock inside the earth's crust.