¹     Did you know that you live on the Earth's crust? Just like bread has a crust on the outside, so does our planet. The Earth's crust is made of rock. It goes from 4 to 25 miles thick in different places. That is much too far for us to dig! The deeper into the Earth we go, the hotter it gets. Under the crust is the mantle [MAN-tull]. The heat within the mantle melts rock! Can you imagine that? If you were to put a rock in a campfire, it would get hot, but it would not melt. It is much hotter than a campfire deep inside the Earth.
 
²     Another name for melted rock is magma [MAG-muh]. You may not have heard of magma, but you probably know what magma is called when it comes out of the earth. It is called lava! It is the color of fire - red, orange, and yellow.
 
³     A volcano [vall-KAY-no] is a mountain made of lava. The magma flows up through a crack or hole -- called a vent -- in the Earth's crust. It becomes lava when it reaches the top of the ground. Sometimes it shoots out into the air! Sometimes it oozes out slowly. Either way, it is called an eruption [ee-RUHP-shun]. When that lava meets the air, it begins to cool. As it cools, it hardens. It becomes rock again. It is no longer yellow or orange or red. It is most often black. The lava forms a hill. The more lava that comes out, the bigger the hill gets. At last it is a mountain.