GEOLOGY OF THE BRISTOL COALFIELD. 283 



**" Lima beds." Near the Ashley Hill Railway Station are found 

 plentifully numerous and well-preserved specimens of Pholadomya 

 glabra, Rhynchonellidae, and a minute Avicula. It is here that 

 fine shells of Pleurotomaria Anglica and Ammonites {Arieiites) 

 Sanzeanus are found. One of our best sections of the Bucklandi 

 zone of the lower lias may be seen near the Saltford Station of the 

 Great Western Railway, shewing the zones of A. Bucklandi, 

 A. Planorbis, and Avicula contorta lying in their relative position 

 as they generally are found in the West of England. — 

 Bucklandi zone, with Lima gigantea, Ostrea 



irregularis, Sec. ... ... ... 30 feet, 



Planorbis zone, with White Lias beds ... 80 feet. 

 Avicula contorta series, with Pecten Valoni- 



ensis, &c. ... ... ... ... 20 feet. 



At the altitude of 367 feet above the sea level we pass into the 

 next zone, containing characteristic fossils of the Ammonites 

 {Arietiies) Turneri which averages in this locality a thickness of 

 30 feet. A very excellent section may be examined near the 

 No. I Orphan House on Ashley Down, very fossiliferous, and lying 

 conformably upon the subjacent strata. At the base, and lying 

 between the Bucklandi and Turneri zones at this spot, may be 

 collected a great many tine specimens of Vertebrsc and other bones 

 of Saurians with fossil wood. 



At Whitchurch in the railway cutting, and weathered on the 

 blocks of Lias limestone, are specimens of Univalves, Naticidae and 

 Cardinise, which occur here in a liner state of preservation than are 

 found in the neighbourhood of Bristol. The varieties of Chem- 

 nitzia and other small univalves are extremely beautiful and 

 exquisitely sculptured. The following is a section of the various 

 strata — 



Dark shales, very great thickness. 



Clay ... ... ... ... ... 30 



Dark shaley Limestone, with Arietitcs Turneri ... i.o 

 Clay with Septaria ... ... ..* ... i3-o 



