Curvelinear 'drapery' flowstone in a Greek cave. Flowstones are deposited from film flow and accrete roughly parallel to the hosts wall surface. Gours, or rimstones are dams building upwards from irregularities in stream channels or on flowstone surfaces. The greatest impound water to depths of several meters producing rims that are strikingly crenulated. Stalactites and Stalagmites are speleothems, which occur in limestone caves. They form through deposition of calcium carbonate and other minerals, which is precipitated from mineralized water solutions. Limestone is the chief form of calcium carbonate rock which is dissolved by water that contains carbon dioxide, forming a calcium bicarbonate solution in underground caverns.