GeologyRocks

A rock composed mainly of calcium carbonate CaCO₃. Limestones comprise a large variety of rocks including carbonate muds and oozes, chalks, ooliths and bioclastic limestone. They form in a variety of environments from deep sea (but above the carbonate compensation depth), temperate seas, tropical sea, lakes and rivers. Most caves are found in limestones due to erosion by acidic water. Limestones erode into karst topography. They are classified according to Folk's and Dunham's Classification. See the Carbonates tutorial for more details.