The book Rocks, hard, soft, smooth, and rough by Natalie M. Rosinsky says:
"Rocks form in three ways. In the first way melted rock bubbles up from inside the earth. then it cools down and becomes hard igneous rock.
Rocks also form when sand and other natural things are squeezed together until they turn hard. This second kind of rock is called sedimentary rock.
The third kind of rock is made from other rocks. Heat and pressure deep inside the earth can change rocks from one kind to another. Metamorphic rocks can come from igneous or sedimentary rock. "
For more information about rocks please visit the Grade 4 science LibGuide at:
http://vlc.ucdsb.ca/c.php?g=156631&p=1026658
