Volcanoes

The roots of the volcanoes lie 40 to 120 miles inside the earth in a layer called the mantle.Temperatures there are as hot as 4000 degrees F,so hot that rock melts like a chocolate bar on a summer day.The hot,melted rock becomes a thick,flowing substance called magma.Magma is lighter than the solid rock shrouding it,and it pushes up through cracks in the Earth.Volcanoes are like sleeping giants.After years even centuries of rest, they awake.Some powerful eruptions blow tops off mountains,flatten forests,and dam up rivers.Volcanoes also shape the earth.They build islands, mountains,plains, lakes,and the ocean floor