Question

Give Reasons: In limestone regions, surface drainage is rarely found.

Answer 1

Karst is a term applied to areas where extensive dissolution of rock has led to the development of subterranean channels through whichgroundwaterflows in conduits (enclosed or semi-enclosed channels). These conduits can vary in size from slightly enlarged cracks to tunnels many meters in diameter and many kilometers in length.

Karst is produced mostly in areas underlain bycarbonaterocks, usually limestones and dolostones. Limestones are usually composed of calcite (CaCO3), and dolostones are composed of dolomite (CaMg[CO3]2). More rarely, other rocks such as evaporites, consisting of gypsum(CaSO4· 2H2O) have been dissolved to produce karst features. Carbonaterocks are relatively soluble in water that is mildly acidified from dissolved carbon dioxide.