1^16 



PROCEEDINGS OP THE SEOtOGTCAL SOCIETY. 



[Feb. 8, 



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2, Worborrow Bay. I have not 

 been able to find any inland sections 

 in the Isle of Purbeck "which throw 

 light on the Punfield formation. But 

 at the western end of the peninsula, 

 in the clifPs of Worborrow Bay, 11 

 miles distant from Swanage Bay, we 

 find another exposure of these beds. 

 At this place the Chalk, Chalk-marl, 

 Upper Greensand, and Gault present 

 the same characters as in Punfield 

 Cove, and, as there, are inclined at a 

 high angle (fig, 3) *. 



The Upper Neocomian (" Lower 

 Greensand") is represented by about 

 40 feet of clays, sands, and ironstones. 

 From these beds I obtained a fine 

 specimen of the highly characteristic 

 Panopcea neocomiensis. 



The Punfield formation is here 

 about 65 feet thick. 'No trace of 

 the blue clays with limestone bands 

 oyster-beds and " beef" is found in its 

 upper part; but its whole thickness is 

 composed of interlaminated clays and 

 sands, with lignite and bands of iron- 

 stone containing a few apparently 

 marine shells. At the base is a very 

 distinctly marked bed of ironstone of 

 a dark reddish-brown colour, contain- 

 ing casts of shells, which were re- 

 cognized by Prof. Edward Forbes as 

 marine. The presence of this bed is 

 recorded in a note on the Map of the 

 Geological Survey. The general suc- 

 cession of the Punfield-beds at Wor- 

 borrow Bay is as follows : — 





that he has examined the Punfield section 

 and found a single specimen of the genus 

 Area, the species being indeterminable, 

 some feet below the Marine Band. This 

 discovery is interesting as a fresh proof of 

 the gradual nature of the change from 

 freshwater to marine conditions. 



* See also Sir Henry Englefield's ' Isle 

 of Wight,' Plate 37, No. 1. 



