Volcanoes may be dormant for many years, but if they do erupt they can cause serious destruction. Volcanoes are found in areas where the Earth’s plates meet. Some underwater volcanoes have grown so high that they create islands. Lava cools and hardens to create either a tangle of sharp rocks or a smooth, billowy surface. This lava destroys plants and animals living in the area, but also brings new mountains, new islands, and new soil to the land.