The Cliefden Caves have developed in the Late Ordovician Cliefden Caves Limestone mainly by solution in the phreatic zone. Speleogenesis has been inhibited in steeply dipping thinly bedded limestone and shows a high degree of structural control. Collapse has been significant in late stage development of the caves. Much sediment has been deposited in the four caves studied in detail - Main Cliefden, Murder, Boonderoo and Transmission. Formed in the phreatic zone, layered clay fill is the earliest sediment deposited and occurs in all but Transmission Cave. The phosphate mineral heterosite is found in these sediments. Subaqueous precipitation deposits deposited in the phreas or vadose pools are distinguished from speleothems by their texture. Aragonite is inferred to have been deposited in these sediments and to have since inverted to calcite. Friable loam and porous cavity fill are the most common vadose deposits in the caves. Vadose cementation has converted friable loam to porous cavity fill. Speleothem deposits are prolific in Main Cliefden, Murder and Boonderoo Caves. Helictites are related to porous wall surfaces, spar crystals result from flooding of caves in the vadose zone and blue stalactites are composed of aragonite. Cliefden Caves belong to that class proposed by Frank (1972) in which deposition has been more important than downcutting late in their developmental history.