As limestone piles up higher and higher, the pressure increases. Limestone may be covered with other sediments, or it may be thrust upward as mountains rise. Pressure creates heat, and the limestone may change, or metamorphose, into marble. Limestones that have been raised above the sea often make great fossil hunting grounds. However, experienced fossil hunters ignore marble, knowing that any fossils it contains have probably been destroyed by heat and pressure.
Limestone is quarried commercially for lime and building stone.
Marble produces even more valuable building stone, since it's harder and can be polished to reveal its beautiful patterns. Some of the world's greatest buildings and monuments are made of marble. Crushed and ground marble has also become valuable in textiles, paints, and other uses. The abundance of limestone and marble in the Appalachians and the Midwest is evidenced by countless place names, from Limesdale to Marbleton to Marble Falls. Tennessee Tennessee designated limestone its state rock on March 13, 1979.