Without help from chemistry and a microscope it would be hard to accept that the rock called limestone comes from sea shells and corals. Outstanding regions of this sort in the United States are the present site of the Rocky Mountains, the valleys of the Mississippi, Ohio, and St. Lawrence rivers, and a large part of Texas.
Limestone has many important uses.
It is the chief source of lime. It wears better than sandstone, is more easily shaped than granite, and weathers from nearly white to a beautiful gray. Oolitic limestone, quarried in Lawrence, Monroe, and Owen counties in Indiana, is a particularly fine building stone. Bedford, Ind., is an important limestone quarrying center. Crushed limestone is used on macadam roads.