Rocks are famous for staying put. If something is as “solid as a rock,” you assume that it’s not going to change or go anywhere.
However, in reality, rocks are always changing and on the move. Nature is constantly recycling them. You see that in mountains, rivers, oceans, volcanoes, and canyons. Even in earthquakes!
Rocks come in about 100 varieties. There are also about 3,500 minerals—the stuff of which rocks are made. Together, rocks and minerals pave streets, give color to paints, decorate jewelry, and put “lead” in pencils. Rocks are even added to food. The iron in cereal and chalk in bread help make bones strong. We put rock salt on food for taste, and we also use salt to preserve foods. Rocks are in toothpastes and cosmetics. While rocks may not have supernatural powers, as many once believed, they do affect our lives.
