OXFORD CLAY. 323 



suiinis, and PUosaiiriis, and of Fishes, such as Lcpidottis, HyloduSy 

 Jschyodus, etc., are occasionally met with. 



Among the fossils of the Kellaways Rock are Bdeinnites Owenii, 

 AinmotiHes Koinigi, A. Gowerianus, A. modiolaris ( siiblcEvis ) , Gryphcca 

 bilobata, Isocardia ienera, Modiola puJchra, Avicula iticcquivalvis, 

 Waldheimia obovata, and the species previously mentioned from this 

 division ; but there is no very definite palceontological or lithological 

 boundary between the Kellaways Rock and the Oxford Clay. 



The Oxford Clay occurs near Weymouth (300 feet or more), and 

 extends across the Vale of Blackmore by Witham Friary, Trow- 

 bridge, and Melksham to Chippenham. Small nodules, called 

 Kidney-stones, composed of reddish-brown ironstone with veins of 

 Calc-spar, are frequently found in the Oxford Clay in the cliffs and 

 on the shore north of Weymouth. Here large specimens of Gryphcca 

 dilataia are abundant. Fossils may also be obtained in the low 

 cliffs of Oxford Clay bordering Radipole Lake and the Fleet. 

 Ophiodcnna Weymoidhicnsis and many other species have been ob- 

 tained by Mr. R. Damon. ^ The Kellaways Rock has not been observed 

 in Dorsetshire, but it was proved in a boring near South Brewham, 

 in Somersetshire. 



In Wiltshire the Oxford Clay is upwards of 420 feet in thickness. 

 Christian Malford, about four miles north-east of Chippenham, is a 

 well-known locality for fossils ; and there, in 1841, when the cuttings 

 were made for the Great Western Railway, Dr. J. Chaning Pearce 

 obtained many fossils from bands of laminated clay alternating with 

 sandy clay. These included Ammonites Jason, as well as Belemno- 

 teiithis, and other Cephalopoda, the soft parts of which, together 

 with the ink-bag, were beautifully preserved.' Many fossils have 

 also been obtained in the neighbourhood of Trowbridge.* 



The Kellaways Rock of Kellaways between Chippenham and 

 Christian Malford is a bed of calcareous sandstone near the bottom 

 of the Oxford Clay, from three to five feet in thickness, and crowded 

 with organic remains. Lonsdale observed that the fossils are 

 occasionally so numerous as to constitute nearly the whole of the 

 stratum, but are often wanting. He gave the following section of 

 a quarry at Christian Malford : * — 



Pale lead- coloured clay, streaked with yellow. 

 Rubbly stone, highly charged with oxide of iron, and in- 

 closing a few organic remains 5 feet. 



Sandstone, abounding with fossils 3 ,, 



Sand 4 ,, 



Clay. 



Alternations of sandstone, sand and clay, representing the 

 Kellaways Rock, and attaining a thickness of 62 feet, were met 



' Geol. Weymouth, etc., 1884, and Supplement with figures of fossils. 



^ Proc. G. S. iii. 592 ; London Geol. Journ. p. 75 ; \V. Cunnington, ibid. 97 ; 

 S. P. Pratt, Ann. Nat. Hist. 1S41, viii. 161 ; Owen, Phil. Trans, cxxxiv. 65 ; 

 Egerton, Q. J. i. 229 ; Morris, Ann. Nat. Hist. xv. 30. 



^ R. N. Mantell, Q. J. vi. 310. 



^ T. G. S. (2), iii. 260. 



