Definition: limestone

A sedimentary rock composed mainly of calcium carbonate (CaCO3), generally soft and permeable, which effervesces when exposed to acid. It often contains fossils. The Loire Valley is home to monumental buildings constructed from blocks of tuffeau stone, sourced from quarries that have often been converted into wine cellars or mushroom farms, offering ideal humidity and temperature conditions. Champagne is also known for its white chalk soils, while Bordeaux, on the right bank of the Garonne, is known for its Saint-Émilion asteriated limestone (fissured soil that allows good root penetration).