TRANSACTIONS OF SECTION C. 505 



places on the Sussex coast westward of Brighton are built, is of very recent for- 

 mation, being composed of gravels, sands, and loam belonging to the post- 

 Pleiocene or Pleistocene series. These superficial post-Pleiocene beds overlie 

 the well-known Eocene series in patches, and contain a large fauna. No less 

 than 66 genera and 142 species, chiefly mollusca, occur here. The remains of the 

 mammoth or elephant {E. primigenius, or antiqiius) occur in the muddy deposits 

 [mud-deposit]. With these are associated marine shells of existing species, but 

 some not known now as such on the Sussex coast. East of Bognor, at low tides, we 

 have the remains of a sunken forest, and west of Selsea the trunks and roots of trees, 

 &c., may be examined at low water. These trees in both areas are not fossilized, 

 but evidently destroyed by the encroachment of the sea, probably since the time 

 when 'the Park' existed. In July, 1877, Mr. H. Willett, of Brighton, obtained 

 from the beach below high-water mark, near East Wittering, a large number of 

 bones of rhinoceros associated with several species of land and freshwater shells 

 of existing species. The bones lay in the midst of decayed trees in a peaty deposit 

 beneath the glacial beds of Selsea. An almost perfect skeleton of the Elephas 

 antiquus is in the Museum at Chichester, which was obtained from the ' mud 

 beds ' or ' mud deposit ' ofl" Selsea Bill ; multitudes of the shell Pholas a-tspata, 

 occur in the same bed. Teeth of the mammoth have occurred in the 'mud- 

 deposits ' of Bognor, Littlebampton, and Worthing ; and we have again the well- 

 known ' Elephant bed' at Brighton, doubtless of the same age. 



At the British Association meeting in 1851, Mr. Godwin-Austen, F.R.S., then 

 president of the Geological Section, called attention to the evidence of repeated 

 oscillations of level, of no very remote date, which were to be observed in parts of 

 the coast of Cornwall, Devon, the Channel Islands, and the Cotentin, an area 

 comprising the western opening of the English Channel. As before stated, the same 

 distinguished physicist, four years later, in his paper 'On the newer Tertiary 

 Deposits of the Sussex Coast,' exhaustively described the phenomena of the later 

 movements of the land, and interchanges between the sea and the coast. The 

 oldest of the newer-Tertiary deposits of the Sussex levels in ascending order is to be 

 seen only at extreme low-water in Bracklesham Bay ; thence eastward round Selsea 

 Bill, as far as the entrance into Pagham Harbour. 



This portion of the Sussex series forms the 'mud-deposit' of Mr. Dixon. Its 

 character and composition distinguish it from the beds above. It is composed of 

 an extremely fine tenacious dark grey sandy mud, which resists the action of the 

 sea ; it rests upon the well-known Eocene Nummulitic strata. 



The thickness of this Lutraria clay or ' mud-deposit,' can only be estimated at 

 low-water spring tides ; in places it is from 18 to 20 feet thick ; it increases 

 seawards and passes away beneath the sea-bed. On the coast near Medmeney 

 (west side of the Bill) the surface of this clay is occupied by the remains of a colony 

 of Pholas ct-ispata, which has burrowed into it. This species attains here to great 

 ■dimensions, and from its restricted range and littoral habit serves to determine the 

 level of the tidal waters at the commencement of the Selsea deposits. The relative 

 age of this old estuarine deposit of Selsea is determined by its mammalian 

 remains. Those of Elephas primigenius are tolerably abundant, and the interest 

 attached to them is enhanced by the fact that they do not occur here as single and 

 detached teeth, or portions of tusks (as occurs on the higher gravels), but so many 

 parts have been found together as to leave no doubt but that entire skeletons still 

 lie embedded in this deposit. The head with the teeth and tusks and numerous 

 bones have been found in close juxtaposition, and are now placed in the Chichester 

 Museum. No less than sixty-six genera and 151 species of mollusca have been 

 found here, or thirty-three genera and eighty-nine species of gasteropoda, and 

 thirty-three genera and sixty-two species of pelycipoda, have been obtained from 

 the Lutraria clay or ' mud-bed.' I may mention, among so many, the rarer shells 

 that occur : — 



Cerithium reticidatum, da Costa. = C. lima, Brug. — A Spanish, Portuguese, and 

 Mediterranean shell, comparatively recent within our area. 



Fusus turricula (Pleurotoma). — A boreal Atlantic species, ^occurs in the Eed Crag. 

 Scarce in the Faluns and Bridlington. 



