This booklet describes the caves of the Gower peninsula. Much of the Gower peninsula is composed of carboniferous limestone. This is a hard grey rock but despite its hardness it can be dissolved by water which seeps between the fissures and bedding planes of the stone, so that over many thousands of years sufficient rock is dissolved to leave the cavities, passages and caves for which limestone country is noted. During the long period since they were formed most of the caves have become partly filled with debris fallen firom their roofs and walls, with soil, sand and dust washed or blown in and with hard layers of stalagmite. Excavations in such deposits during the last two hundred years have recovered the bones of animals belonging to species now extinct or no longer found in Britain. Three caves in the Pennard cliffs alone contained the remains of Straight-tusked Elephant, Soft-nosed Rhinoceros, Hippopotamus. Mammoth, Bison, Reindeer, Cave Bear, Wolf, Hyaena and Lion.