Volcanoes are mountains made from molten rock. The Earth�s crust is divided into big slabs, called plates, which are slowly moving all the time. The plates are floating on the Earth�s mantle, a layer of gooey hot rock that flows like maple syrup. Some places in the mantle, the rock gets very hot and nearly liquid. It�s called magma. Sometimes the magma reaches the Earth�s surface and forms a volcano.
click here to see where to watch or .
Ready to Watch Bill Nye The Science Guy, Season 4, Episode 14?