Rumbling and grumbling, they empty out their crater . When volcanoes erupt, steam, gases and rocks are pushed up from deep inside the earth. It is very hot in the middle of the earth. Volcanoes can erupt at any time, spitting out melted rock called lava . Lava is so hot it boils out of the crater and flows down the slopes of the volcano.
Young volcanoes erupt many times as they grow up.
They often have a beautiful, sloping shape, like an upside down cone or a funnel. Sometimes a little volcano grows on the side of a young volcano. It smokes and puffs like the bigger one. They can both erupt. Older volcanoes may be huge mountains.