Two major lithostratigraphical units are represented in the cave fill, the Siliceous Member, a complex of waterlain silts, sands and gravels with a comparatively sparse derived fauna, which is overlain by the Calcareous Member, a finely stratified sequence of cave earths and breccias, rich in vertebrate remains, principally those of mammalian carnivores and small mammals. At present a little over 55 mammalian species are represented in the collections from Calcareous Member, as well as numerous birds, reptiles, amphibians and fish. Changes in the vertebrate fauna and episodes of speleothem formation show that the environment fluctuated between cold conditions with tundra or boreal forest and fully temperate episodes supporting deciduous woodland. The sequence records at least two temperate phases (units 11-12 and unit 15) separated by a cool interval (units 13-14) and a further period of cold-cool conditions at the top of the sequence (top of unit 15 and in the Main Chamber units 18-19). There may also be an early warm phase (unit 8) followed by a cool phase (units 9-10).

Claims for stone tools remain controversial, but a single cut-marked bone from unit 19 provides compelling evidence for a human presence.

Mammal remains from the Siliceous Member (‘Westbury 1’ of Bishop 1982) comprise a variety of derived material, much of it fragmentary and heavily rolled, and possibly heterogeneous in both source and age. The fauna includes hyaena, rhinoceros and a bovid; micromammals are much rarer, but include the only British record of the vole Microtus (Allophaiomys).