ZONE OF AMMONITES PLANORBIS. 



55 



and Wilmcote, in Warwickshire ; and at Pinhay Bay and Up Lyme, in Dorset. I purpose 

 giving a detailed description of the most typical sections in each county. 



Somersetshire. — At Street the strata are nearly horizontal and undisturbed, and there- 

 fore admit of accurate measurement. The following section of Mr. Cree's quarry I have 

 compared with like sections afforded by the quarries of Messrs. Seymour, Underwood, and 

 Talbot in the same parish ; and find that the variation is so inconsiderable that any one 

 may be said to represent the others, both as regards the sequence of the beds and the 

 fossils they contain. 



Section of the Zone of Ammonites planorbis, at Street, Somerset. 



LiTHOLOGY. 



No. ft. in. 



1 . Light-coloured marly clay .3 0 



2. Light-coloured Lias limestone 0 9 



3. Yellowish laminated shale, splitting up 



into thin layers 3 0 



4. Light-coloured shaly limestone 0 4 



5. Hard gray limestone 0 7 



6. Dark- gray shale 0 3 



7. Dark-gray limestone 0 6 



,' 8. Dark laminated shale 0 4 



9. Dark -gray limestone 0 5 



10. Dark shale 0 3 



11. Dark-gray limestone 0 6 



12. Dark shale 0 6 



13. Grayish hard limestone, consisting of 



two 4-inch beds 0 8 



14. Hard dark marl 0 9 



15. Grayish fine-grained limestone 0 3 



16. Brownish limestone 0 4 



17. Dark-coloured limestone 0 4 



Organic Remains ; and the Local Names of Beds. 



Planorbis Series. 

 " Top Bed." Saurian bones and Ammonites 



planorbis. 

 Ammonites planorbis in moulds. 

 Ichthyosaurus intermedins, Ammonites planorbis, 



Lima punctata, and Isastrcea Murchisoni. 

 Ammonites planorbis, compressed. 

 "Building-stone." Ammonites planorbis, on the 



top of the bed, Lima punctata and Lima 



gigantea. 



Ammonites planorbis, and muricated spines of 



Cidaris, Edivardsi. 

 " Corn-sized building-stone." Spines of Cidaris 



and bones of Ichthyosaurus tenuirostris. 

 Ostrea Series. 



Ostrea liassica. 



" Five-inch building-stone." Ostrea liassica. 

 Ostrea liassica. 



" Six-inch building-stone." Cardinia crassiuscula, 

 Lima punctata, and Ostrea liassica. 



"The Whetstones." Best paving-bed. Fossils 

 rare : Ostrea liassica and Modiola minima. 



"■ Saurian bed." Many Saurians have been ob- 

 tained here. Ichthyosaurus intermedins and 

 Plesiosaurus Hawtcinsii (British Museum). 

 Jaws of Saurians and Fishes. 



"The Cream-bed." Fine-grained paving - stone. 

 Ostrea and Modiola. 



"Red Liver." Paving-stone. Few fossils. 



The "Black stone," used for large paving-slabs; 

 some of them 10 ft. by 5 ft. Modiola minima, 

 Ostrea liassica, Myacites, and Bhynchonella 

 variabilis. 



