1853.] TRIMMER — SUPERFICIAL DEPOSITS, ISLE OF WIGHT. 53 



freshwater limestoDC, which must have required considerahle force of 

 water for their transportation. 



Section of the Superficial Calcareous Deposits, Tolland's Bay. 



Eocene Sands. 



a, Calcareous tufa — land-shells : 10 inches to 2 feet. 



b, Sand blackened by organic matter — calcareous concretions and land-shells : 



4 to 12 inches. 



c, Cream-coloured marl, with calcareous concretions, and a few thin black seams 



coloured by vegetable matter — land-shells : 2 feet 6 inches. 



d, Warp-drift of brown loam : 5 feet. 



Further to the N.E. the warp-drift appears under its usual cha- 

 racter, often gravelly towards the base, and with no calcareous beds 

 below it, but filling indentations and furrows in the bed on which 

 it rests, whether that be flint-gravel or one of the eocene strata. On 

 the S.W. it only appears at intervals, being partially concealed by 

 the debris of the upper part of the cliif or by vegetation. At the 

 base of Headon Hill it is well exposed, and accessible for examina- 

 tion for about thirty yards along the face of the cliff, while a gully 

 has laid open a transverse section for about fifty yards in the interior. 

 The warp-drift is there thinner, furrowing the surface, and varying in 

 depthfrom 1 to 3 feet. The calcareous deposits are at least 1 2 feet thick, 

 and consist of several alternations of cream-coloured marl, calcareous 

 tufa, and bands of sand and clay blackened by organic matter. The 

 thickness of these bands of sand and clay varies from 2 to 6 inches ; 

 that of the calcareous tufa from 6 inches to 2 feet. Land shells are 

 distributed throughout the whole deposit. Some of the concretions 

 in the calcareous tufa are cylindrical, some subglobular. The former 

 have a cylindrical cavity in their centre, which is occasionally filled 

 with decayed vegetable matter. These have evidently been formed 

 around twigs and stems of plants. The subglobular concretions, after 

 exposure to the weather, by which the outer calcareous coats have 

 been removed, have so much of the form of the Helices and Cyclo- 

 stomse with which the deposit abounds, as to render it probable that 

 they have had shells for their nucleus. 



The species are — Helix arbustorum or nemorum ; Helix hispida ; 

 Cyclostoma elegans. 



A. very careful search for freshwater shells only gave one large 



