Caverns

Caverns occur under the surface of the Earth wherever soluble rocks allow them to develop large openings. Limestone or calcite-rich (CaCO3) bedrock is the most common host rock, as well as dolostone rocks composed of the mineral dolomite (CaMg(CO3)2). The evaporite rocks of gypsum (CaSO4) and rock salt (NaCl) are also subject to solution and can develop underground [Page 367]openings large enough to be considered caverns. In a few places, caverns have developed in other rock lithologies, such as where a calcite-cemented sandstone has also been subjected to solution. Several natural processes other than the dissolving of the bedrock can also produce caves, such as ocean waves and lava flows, but these are almost never large enough to constitute a true cavern, which has an ...