346 Prof , Sedgwick on the [May, 



(1.) Ostrea, 



(2.) Venus. 



(3.) Cer it Ilium, 



(4.) P la nor bis. 



(6.) Lymima, 

 , ; The lower portion of the diff between Gurnet Point and East 

 iOowes presents many examples of the mixture or alternation of 

 marine and freshwater genera, which cannot be accounted for 

 merely by the degradation of the upper part of the clilF. This 

 fact, and the probable reasons of it, are both stated by Mr. 

 Webster (Geol. Trans, ii. 213). In every portion of the coast 

 where there is any escarpment between Whitecliff Bay and Bem^ 

 bridge Ledge, and also between the mouth of Brading Harbour 

 and Priory Park, we found well defined beds of the lower fresh- 

 water J'ormation. We have already remarked their junction 

 with the vertical beds of Whitecliff' Bay. Immediately to the 

 north of this junction, and from thence to Bembridge Ledge, 

 many of these beds lose the character of indurated calcareous 

 marl, and pass into a variety of hard shell Umestone. In this 

 state they are quarried to a considerable extent, and the larger 

 blocks are cut down by a saw into forms which are suited for 

 exportation. These rocks do not, as far as we observed, contain 

 any marine spoils ; but they exhibit innumerable traces of the 

 common freshwater fossils ; viz. paludina, planorbis, and lymnsea. 

 Nor are they, as in some other places, at all confounded with 

 the marine marl which rests upon them. A thin oyster bed of 

 the upper marine marl may be traced in many parts of the bay 

 where there is a clean escarpment, in almost immediate contact 

 with the inferior rock. The beds just described have been 

 referred by mistake to the upper freshwater formatio)i. (Geol. 

 Trans, ii. 228.) It would hardly have been necessary to notice 

 this oversight had it not been copied by those who have described 

 this part of the island without any personal examination of it. 

 Either a dislocation, or at least a considerable flexure, of the 

 freshwater strata, takes place at the entrance of Brading har- 

 bour; for on the south side of the harbour tliey dip to the north, 

 but on the north side of it they dip at a more considerable angle 

 in an opposite direction. The remaining part of the chfF as far as 

 Priory Park presented a repetition of the same phenomena, vi^. 

 the lower freshwater rock surmounted by the argillaceous marl of 

 the upper marine formation. The demarcation was, however, no 

 longer well defined, but showed a mixture or alternation which 

 probably originated in a gradual passage of one formation into 

 the other. An examination of this part of the Island convinced 

 us that Mr. Webster had correctly classed the calcareous beds 

 near Ride with the lower freshwater formation. We had before 

 adopted a contrary opinion. In addition to the difficulty of 

 accounting for the appearance of any portion of the upper Jresh- 

 water rock in the cliii' between Gurnet Point and Ride; we may 



