Geology of the Neighbourhood of Weymouth, ^c. 21 



meridg-e clay ; it seems to form a connecting link between the Portland stone 

 and Kimmeridge clay ; and, as has been observed by Mr. Conybeare*, is pro- 

 bably identical with the beds of sand and green earthy, full of large boulder- 

 shaped semi-calcareous concretions^ that occur in Shotover Hill, near Oxford, 

 between Kimmeridge clay and the imperfect upper calcareous Portland beds, 

 which extend from Shotover to Brill and Thame and Aylesbury, and which 

 also are occasionally much loaded with grains of green earth. Dr. Pitton 

 has recog-nised this sand beneath the calcareous Portland beds at Whitchurch 

 in Bucks: it occurs also in the same position in the Quainton Hills; and 

 Mr. Lonsdale considers the sand which forms the escarpment close on the 

 north and west of the town of Swindon to be also identical with this Portland 

 sand ; the calcareous or upper Portland beds occur also beneath and a little 

 to the east of that town. In the Boulonnois, Dr. Pitton describes this forma- 

 tion as consisting of calcareous concretions of great size, as in Oxfordshire 

 and Bucks, abounding in petrifactions, and imbedded in yellowish somewhat 

 ferruginous sand ; between Gris-nez and Audreselles the shore is covered 

 with these enormous masses fallen from the sandf. 



Kimmeridge Clay. 



The general character and fossils of this formation have been already 

 described by Conybeare and Phillips. It is chiefly composed of beds of slaty 

 bituminous clay, interspersed with Septaria and beds of bituminous marlstone. 

 Near its middle region, in Ringstead Bay, it contains thin beds of marly 

 sandstone, full of well preserved organic remains^ and through its whole 

 extent it is loaded with deltoid oysters, which are well known to be its most 

 characteristic shell in England ; it contains also the Gryphaa Virgula, which 

 is considered characteristic of this formation in France, and abounds in it at 

 Shotover near Oxford. 



Mr. James Sowerby has prepared the following list of fossils from this 

 marly sandstone in Ringstead Bay. 



A carinated Serpula. 

 Mya depressa, M. C. 418. 

 Pholadomya, near Ph, ohtusa. 

 Venus ? 

 Cardium ? 



Trigonia elongata, M. C. 431. 

 Modiola bipartita, M. C. 210. f. 3, 4. 

 , a small boring species. 



Pinna granulatal a small fragment, M. C. 347. 

 Ostrea deltoidea, M. C. 148. 

 Terebratula inconstans, M. C. 277. f. 3, 4. 

 Pleurotomaria reticulata (Trochus), M. C. 272. 



f. 2. 

 Ammonites, species between A. decipiens and 



A. mutabilis. 

 Ammonites rotundas, M. C. 293. f. 3. 



* Outlines of the Geology of England and Wales, pp. 166, 173, &c. 

 t Philosophical Magazine, 1827, New Series, vol. i. p. 139. 



