42 



The White Lias series is 8 feet thick, and well defined; the 

 Gotham Marble Bed at the base being 10 inches in thickness, 

 and is underlaid by 16 feet of grey shales, indurated, and 

 ripple marked. The White Lias is here overlaid by a remark- 

 able series of laminated, slaty, and marly Shales (Pullastra 

 Shales) which weather into cavernous holes. A peculiar species 

 of Pullastra occuring in thousands, constituting the mass of 

 these Shales, 5 feet 6 inches in thickness, they stand between 

 the Ostrea series above, and the White Lias below, a most 

 marked feature in the section. The commencement or lowest 

 bed of the Ostrea series is equally well marked, being a solid 

 bed of hard grey Argillaceous Limestone fissUe at the top, and 

 full of Ostrea Liassica and Modiola minima and other shells ; 

 the Ostrea beds measure 15 feet, the same fossils occurring 

 through the whole. These are the Saurian beds of the Somer- 

 setshire area, and the whole constitute a very definite ridge 

 upon the foreshore, as well as an abrupt facing in the cliff: 

 equally definite and distinct, physically, and palseontologically 

 are the Planorbis beds above, marked everywhere by the 

 Ammonite, giving name to the group of strata here 24 feet 

 thick ; of the 24 feet, 16 feet is composed of fissile shales, and 

 in the upper 5 feet the shells of the Ammonites are completely 

 converted into, and replaced by, Selenite. The remaining thick 

 series of Strata, (50 feet exposed,) capj)ing the Planorbis beds, 

 belong to the Bucklandi and Lima series of the true Lias, and 

 which form no part of my paper. They constitute the fine 

 coast line east of St. Audrey's to Little Stoke where the Ehsetic 

 beds are again exposed through a series of north and south 

 faults. 



Section in Railway South of Watchett. 

 No. VII. 

 When the Railway was first opened, or during its construction, 

 about 70 feet of Shales and Limestones of the Ehsetic series 

 were exposed ; eight well defined bands of calcareo-siliceous 

 rock occur interstratified with the Black and Brown Shales ; 

 the base of the section was not exposed, but the Grey Marls could 



