P3+-+Volcanoes

Volcanoes are created when two plates colide and one of the plates go under. When that happens the plate gets so hot the ground turns into a hot molten rock. Then the molten rock finds a hole and the molten rock pours out. The volcano explodes because of the gas buildup. When the gas builds up the lava blows out the top. When it cools it turns into a shiny black rock, this rock is called obsidian.