go 



[Proc. B.N.F.C., 



than for walking through long "marram" grass to discover sections,, 

 still important evidence was obtained. In the wind-eroded 

 sections old dune surfaces were common, representing temporary 

 pauses in accumulation. These often contained shells : Helix 

 nemoralis and Cochlicopa lubrica being the only species noted. 

 In the " midden " layer the former species occurred also. The 

 source of the vast majority of the " pocket " shells has yet to be 

 discovered, but probably it will be found to occur beneath this 

 layer. The abundance of Helix nemoralis in the bottom of the 

 valleys arises from the fact that as the wind erodes the upper 

 layers the large shells roll down the slopes. The " pockets " 

 contain many damp-loving species such as Carychium minimum, 

 several species of Vertigo and Hyalinia, Clausilia bidentata, and 

 Acanthinula aculeata, mixed with many dune shells. It is 

 obvious that these species cannot have lived together, and as since 

 the " midden " period the conditions have only been suitable for 

 " dune " species, it appears that the other species must be pre- 

 midden in age. 



In the sandhills at the mouth of the River Bush, and close 

 to the bridge which carries the tramway across the river, is a 

 gravel pit shewing about 4 feet of gravel overlain by about 12 feet 

 of blown sand. In the sand at a depth of about 6 feet Mr. A. W. 

 Stelfox discovered a " fossil shell pocket." This contained the 

 usual admixture of dune and damp-loving species, the two most 

 abundant being Hygromia hispida and Helicella barbara. Small 

 examples of Succinea pfeifferi also occurred, which must have 

 been blown by the wind from the river bank. Here again we 

 failed to find any land-shell deposit at the base of the sands. At 

 Whitepark Bay no land-shell deposits were noted either, though 

 Helix aspersa certainly occurred in the upper part of the midden, 

 which is probably of Bronze Age, whilst the true Neolithic layer 

 yielded Helix nemoralis, Hygromia hispida, Hyalinia nitidula, 

 and Clausilia bidentata. The evidence thus obtained from these 

 sandhills fully supports the views derived from the observed facts 



