266 JURASSIC. 



the Lias exhibits a remarkable attenuation from paucity of sediment.^ 

 At Camerton, Timsbury, Paulton, and other localities near 

 Radstock, fine specimens of Spirt' fera Walcottii have been obtained. 

 They were originally discovered by John Walcott, and their 

 position was defined by Mr. Moore as equivalent to the Spirifer- 

 bank of Quenstedt ; ^ they occur in the zone of Anunonites Buck- 

 landi. 



Quarries between Paulton and Radstock have, in a thickness 

 of about ten feet, yielded evidence of the zones of A. planorbis, 

 A. Bucklandi, A. obtusus, A. raricostatus, A. armatus, and A. 

 Jamesoni? The sections differ much in detail, within short 

 distances, but the beds are usually very fossiliferous. At Keynsham, 

 Pennyquick, near Twerton, Weston, and other places near Bath, the 

 Lower Lias limestones have been extensively quarried. From one 

 of the quarries the original specimen of Ammonites Bucklandi was 

 obtained. This, like some other species, is occasionally found of 

 great size, and without the inner whorls ; and such was the case 

 with the specimen originally obtained by Dr. Buckland, who, 

 thrusting his head through it, rode home, dubbed by his friends 

 the Amnion Knight} There is a legend that St. Keyna, from 

 whom Iveynsham takes its name, resided there in a solitary wood 

 full of venomous serpents, and her prayers converted them into 

 stones, which still retain their shape. '^ 



In Glamorganshire the Lower Lias or Lias Conglomerate 

 frequently exhibits shore-conditions. The beds are well exhibited 

 in the cliffs at Sutton, Southerndown, and Dunraven ; and inland 

 at Brocastle and Ewenny, near Bridgend, at Cowbridge and other 

 places. The fossils include Isastma globosa, Monti ivaltia, GrvphcBa 

 incurva, Pccten Pollux, Ostrea Liassica, Lima gigantea, etc. Some- 

 times the beds approach in character the Carboniferous Lime- 

 stone, so that it is difiicult to distinguish between them. The 

 Conglomerates are formed of Carboniferous Limestone pebbles. 

 The clayey beds of the Lias are not represented. Mr. Bristow 

 has stated that on the shore, where the sections are exposed 

 to the influence of sea-water, they have become silicified, and so 

 hard that it is exceedingly difficult to hammer the fossils out of 

 the rock ; while the calcareous shells of the fossils themselves, 

 between high- and low-water mark, have sometimes been replaced 

 by chalcedony. The Sutton-stone is a white tufaceous stone. 

 (See p. 249.) 



The Lower Lias is largely developed in Gloucestershire, Wor- 

 cestershire and Warwickshire. The zones observed in Gloucester- 

 shire have been previously noted; thai oi A. planorbis has been 



^ Q. J. xxiii. 470. 



- Walcott, Descriptions and Figures of Petrifactions found in the Quarries, etc., 

 near Bath, 1779 ; Moore, Q.J. xxiii. 471. 



3 E. B. Tawney, Proc. Bristol Nat. Soc. (2), i. 167 ; Tate, Q. J. xxxi. 493. 



* Sovverby, Mineral Conchology, ii. 69. 



5 See Nat. Hist, of Selborne, by the Rev. Gilbert White, edit, by T. Bell, vol. 

 i. p. 480. See also Scott's Marmion, Canto 2, xiii. 



