Vol. 60.] SECTIONS IN THE BRISTOL DISTRICT. 179 



No. Feet inches. Formation. Fossils. 



18. 5 Upper Pecten-Bed, hard Pecten valoniensis, Placunopsis al- 

 grey limestone. Usually pina. Locally it is thinly-bedded 

 double, with 4 inches of and crowded with Acrodus mi- 

 shale intervening. The nimus, Pleurophorus elongatus, 

 top often covered with Saurichthys apicalis, S. acumi- 

 crushed shells. natus, Gyrolepis, Hyhodus-spm.es, 



bones, coprolites, etc. ; Ichthyo- 

 saurus, Plesiosaurus, Termato- 

 saurus. 

 17. 8 Black shales, with * Pul- Avicula contorta, Axinus, Cardium 



lastra '-bands. rhceticum. 



16. 8 Lower Pecten-Tiimestone ; Pecten valoniensis, Avicula con- 

 shaly on the top, full of torta, Axinus cloacinus, A. con- 

 Pecten. Locally very centricus, Cardium rhceticum, 

 pyritous. C. cloacinum, Gervillia precursor, 



Modiola minima, Myacites striato- 

 granulata, Anatina, Anomia ; 

 Gyrolepis Albertii. 

 15. 4 Black shales, with arena- Fish-scales ; the arenaceous bands 



ceous bands. contain ' Pullastra! 



(15a. The upper part of this is hard, fissile 'Paper-Shale,' very 



barren, 16 inches thick.) 

 14. lto6 Bone-Bed. 

 (13-1.) (See Etheridge's paper, op. supra cit.) 



In addition to the fish-remains enumerated above, the Pleuro- 

 jjhorus-b&nds (18), which are very abundant on the beach, yield 

 numerous rounded quartz-pebbles, varying in size up to half an inch. 

 There are no other pebbles, and the general grain of the bed is fine. 

 These will be referred to later (p. 182). 



The discovery of Estheria and Naiadita is interesting, as linking 

 Aust with other Rhsetic exposures, notably that of Westbury-on- 

 Severn. These fossils are by no means common, but I have 

 obtained several specimens of each. 



III. The Physical Geography op the Rustic Period, 



(A) An Account of the Constituent Beds, with special 

 reference to the Conditions of their Deposition. 



(a) The infra-Bone-Bed Series. — Some would include here 

 the Tea-Green Marls, which will be discussed later. But there are 

 occasionally Rhsetic strata below the Bone-Bed. As will be seen in 

 the next section, by the Bone -Bed I mean a layer low down in 

 the Black Shales containing bones, teeth, and pebbles or rolled 

 marl, thus distinguishing it from other layers rich in teeth. 



At Watchet the infra-Bone-Bed Series is fossiliferous (6). At 

 Redland, and at Stanton-on-the-Wolds (31), Black Shales lie 

 beneath the Bone-Bed. 



(b) T h e B o n e-B e d. — This is one of the most characteristic of the 

 constituents of the Rhaetic Series, not only in England but also in 

 Germany, France, etc. Yet, despite its wide distribution, from 

 Gainsborough (12), and Nottingham (31), through Penarth, Aust, 

 "Watchet, and Bristol to the Mendips at Emborough (48), and thence 



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