A volcano is an opening through which lava and magma can escape. The magma builds underground until it forces its way through. Depending on the thickness and consistency, the eruptions can be silent, smooth flows which make no clouds or ash and leave behind a gently sloping hill known as a shield volcano. Or they can be violent explosions, shooting lava, rocks and ash miles into the sky. These volcanos often create pyroclastic flows; hot, melting ash, streaming across miles and miles of land, burning and burying everything. These volcanos are usually more like what people typically think of and form towers of rock, often collapsing in on themselves after the eruption.
Pliny the younger survived one of these eruptions. He was in the town of Pompeii when the famed Mt. Vesuvius erupted. Here is what he says: “Behind us were frightening dark clouds, rent by lightening twisted and hurled, opening to reveal huge figures of flame. These were like lightning, but bigger.”