296 



the surface before reaching the jetty on the southern side of the point. Most 

 of the clay deposits of newer date have been removed by denudation from the 

 surface of the f ossiHf erous rock ; the latter faces the sea in scarps and terraces, 

 the white colour of the stone having suggested the name of the headland. 



The main bed in the fossiliferous series consists of whitish Turritella clays 

 (T. aldingae), probably representing the same horizon as the darker-coloured 

 clays, rich in Turritella, seen at Blanche Point, a few miles further to the south. 

 While the gasteropod mentioned is extraordinarily abundant at Witton Bluff 

 there is a scarcity of other fossil remains. Next to Turritella the most common 

 occurrence is a large form of polyzoa, which, although possessing only a very 

 thin zooecium, spreads out into large convoluted fans that make masses up to 

 18 inches in diameter. In no case is it well preserved, often only a ferruginous 

 line marks the outline of the form. It has the habit of growth possessed by 

 Retepora, and probably belongs to that genus, but I have been unable to examine 

 the celluliferous surface. Another common, but equally badly preserved, fossil 

 occurs in large bunches of cylindrical and dichotomous stems, but failed under 

 examination to give structure. It is often converted into a ferruginous cast 

 and is probably a coral. The habit of growth of this organism 

 suggests either Amphihelia striata. Ten. Woods, or Cladocora contortilis, 

 Ten. Woods. Other fossils obtained included Dentalium (Entalis) subfissura, 

 Tate ; a considerable variety of spines belonging to the Echinozoa ; and frag- 

 ments of the stems of the interesting and rare crinoid, Pentacrinus stellatus, 

 Hutton ; Ditrupa zvofmbetiensus, McCoy ; and one of the calcareous plates of 

 a Cirriped that retains the original colour bands. A washing of the white clay 

 yielded a very large number of monactinellid sponge spicules. 



Resting on the Turritella clays (which are about 20 feet in thickness) is 

 another whitish clay, more friable than the underlying bed and more sparingly 

 fossiliferous ; in it the Turritellae are rare. The upper white clay is about 

 equal in thickness to the lower and more fossiliferous bed, and the whole section 

 of the marine series, on the southern side of Witton Bluff, may be estimated 

 at about 40 feet in thickness. 



In passing to the northern side of the Bluff, the beds outcropping more to 

 the southward disappear, having been denuded as the result of a rise in the angle 

 of dip, and lower beds of glauconitic sandstone make their appearance. These 

 are highly fossiliferous and include a greater variety of forms than the beds 

 higher in the series, consisting chiefly of mollusca, but the shells are matted 

 together and somewhat difificult to obtain entire. 



Fig. 2. 



Two Stratigraphical Unconformities seen on the North side of Witton Bluff. 



R, Recent Clays. L, Pleistocene Mottled Clays with subangular stones irregularly 



distributed through the Clay. F, Freshwater Beds that underHe the 



Fossiliferous Miocene. 



