Earth

Caves

Caves and water

Water circulation

Water that is normally present in porous rocks, such as sand or gravel, fills all the voids in a continuous manner. However, in karst rocks, the water forms courses of water which at times become large underground rivers that flow in enormous galleries whose diameter is many meters wide and are many kilometres long. The water of the underground streams flows in the same way as those on the surface, and similarly they are subjected to floods caused by rainfalls on the surface (in caves, floods arrive with a certain delay in time, due to slow seeping in the catchement zone). Water is able to entrench and erode rock by means of mechanical abrasion processes, to transport sediments of various granulometries, and to create alluvial deposits inside caves.