There are three types of volcanoes based on the kind of lava, ash and cinders that erupt and the viscosity of the lava.

• Shield volcano: Broad, gently sloping volcanic mountains. They erupt hot, flowing basaltic lava that travels a distance before becoming a solid.
• Composite volcano: Tall with steep sides. They often have secondary vents.
• Cinder cone: Small volcanoes with steep sides. Ash and cinder is formed and ejected from this volcano into the air then back onto the volcano.

Another diagram also shows how hot-spot volcanos are formed. These volcanoes take place in the middle of plates and are stationary. The plate moves back and forth, which forms a chain of volcanoes over time. There are also three types of volcanic rocks: pumice (light, sponge-like), lava bombs (formed from a glob of magma) and obsidian (shiny in appearance, dense volcanic glass)