Vol. 67.] WEST, MID, AND EAST SOMEKSET. 9 



Lower Lias. 



Above the Watch et Beds come the ' Paper-Shales ' of the Lower 

 Lias and the Ostrea Beds. The Paper-Shales are very distinct from 

 the underlying Watchet Beds, and it may be that in between is the 

 stratigraphical position of Moore's ' Insect- and Crustacean Beds ' : 

 beds which are well-developed at Camel Hill. It is pleasing to 

 find that this careful stratigrapher, Charles Moore, held that these 

 beds were often absent ; but he did not sufficiently emphasize the 

 point. In many parts of Somerset, as at Curry Bivel and on the 

 Nempnet outliers north of the Mendip Hills, the top-bed of the 

 Langport Beds is pierced by annelid-like perforations. The imme- 

 diately superincumbent strata are generally the Ostrea Beds, and 

 the perforations furnish evidence of a non-sequence. 



Thus it appears that the reason why the several subdivisions of 

 the Bhastic are so well marked off one from the other, both as regards 

 faunal and as regards lithic characters, is because generally they are 

 non-sequentially related. A study of the English Rhaetic supports 

 Suess's statement that, while the dominant movement was one of 

 subsidence and not local but extended, it was, nevertheless, not a 

 sudden event, ' but oscillatory and slow.' x 



The following table will show at a glance the classification of 

 the Rhaetic Series followed in this paper ; its relationship to the old 

 arrangement ; and also the thicknesses of the several stages of 

 deposit, as noted in the South-West of England — between Gloucester 

 and the English Channel. 



Table I. — Classification of the Rh^tic Series. 



Approximate 

 thicknesses in 

 Lias. Lower. Ostrea Beds, etc. England. 



f I. Watchet Beds (' Marly Beds > to 7 ft 7 ins 

 of the White Lias ') ) 



Rhjetic <! 



Uppers IL Lan SP OTt Beds ( Wllite Lias ] to 25 feet. 



proper) J 



\ III. Gotham Beds (< Upper > a fl ing to M ft 



I Rhaetic') > 



r IV. Westbury Beds (Black Shales) 1 to (?) 47 feet. 

 Lower j y. Sully Beds (Fossiliferous 7 to 14 feet 



*■ Grey Marls) ) 



v C T . C Grey and Tea-green Marls about 11 to 115 feet. 



JvEUPER *) LPPER ^ _. , , r 1 



(. L Red Marls. 



The sequence of maxima of notable fossils has been inserted in 

 Table II (p. 10). 



1 'The Face of the Earth ' (Transl. H. B. C. Sollas) vol. ii (1906) p. 263. 



