Karst landscape, cut-away illustration. This is a type of landscape that occurs in regions with limestone bedrock. Rainwater erodes the rock because carbon dioxide from the atmosphere dissolves to form a weak solution of carbonic acid. This leads to distinctive features formed as small joints and fissures in the rock are enlarged. From left: sinkhole where a stream falls into a vertical shaft; limestone pavement; underground caverns with stalactites and stalagmites, formed as dissolved minerals come out of solution; natural bridge (top); and at lower right, a resurgent stream where water emerges from underground.