Cave / Karst Systems. Hidden within the Grand Canyon are an estimated 1,000 caves. Of those, 335 have been recorded. Very few have been mapped or inventoried. Most have developed in the limestone of the Redwall and Muav formations, although some are known to exist in other formations. Some caves are well known and, over the years, have been frequented often by visitors, such as the Cave of the Domes on Horseshoe Mesa.