The scenery of underground cave systems is developed by the slow deposition of calcite on the ceiling, walls and floors of the caves. Water flows underground through joints in the limestone and along bedding plates forming underground caves, caverns and streams. Re-deposition of calcium carbonate as calcite crystal forms stalactites hanging from the ceiling, stalagmites on the floor and pillars where these two features fuse. Flowstone forms on the walls of caves. It takes thousands of years for these features of underground scenery to form.

First broadcast:
17 February 2001

Students could produce annotated diagrams explaining the formation of the different physical features. They should consider both chemical weathering and abrasion as factors affecting how quicky erosion features form. Discuss the rate at which different features form and how this relates to rate and amount of water flow. Look at geological maps and sections of the Malham idea to get an idea of water flow paths.