204 rEOCEEDINGS OF THE GEOLOGICAL SOCIETY. [Mar. 20 



laminate fossilizatioii of the species, and a trace of the lateral groove 

 which pecnliarizes typical Gryphcea " *. 



Dr. Duncan has already expressed his opinion that the Sutton 

 series is above the Ehsetic beds, although he does not class it with 

 the Lower Lias, but with what he terms Infra-Lias f. 



In his memoir, Mr. Tawney has given the figures and descriptions 

 of twenty species of MoUusca, found by him in the Sutton Stone, aU 

 of which are stated to be new, and claimed as E-haetic species. 



This is a discovery of much interest ; but at the same time it is 

 scarcely necessary to remark that the occurrence of so many new 

 forms of shells affords no evidence, one way or the other, as to the 

 real age of the beds in which they are found. 



So far from proving the beds to be E-hajtic, the argument that 

 they are Liassic may be urged with greater force, because they come 

 out of strata in which the most characteristic of Liassic shells occur, 

 and are there associated with them. 



One of the great difficulties felt by Mr. Tawney in fixing the 

 precise position of the Sutton beds in the geological scale, was the 

 want " of any section showing the position of the Avicula-contorta 

 sandstones [or undoubted Rhastic beds] in relation to the Sutton and 

 Southerndown Series " (p. 78). 



This difficulty is overcome by means of the sections displayed at 

 the Stormy Cement "Works, north of Llangan, and at St. Mary Hill 

 Common. 



The section at the Stormy Cement Works, on the south side of the 

 railway, rather less than two miles east of Pyle Station, shows about 

 20 feet of ordinary Lias hmestone and shale, resting upon 2 feet 

 of a hard, siliceous, and sheUy blue conglomerate, under which occur 

 from 12 to 15 inches of pale argillaceous limestones, breaking with 

 a smooth conchoidal fracture, and which I believe to represent the 

 "White Lias " or uppermost member of the Ehaetic series. 



The conglomerate of the Stormy Cement Works I take to be the 

 attenuated representative of the conglomeratic Sutton Stone in its 

 northerly extension, beyond which locahty it probably extends 

 beneath the ordinary Lias only a short distance before it altogether 

 thins out. 



I^ear Llangan, round which locality the Sutton Stone spreads over 

 a large area, it undoubtedly is based upon the sands and shales of 

 true Ehsetic age, as may be seen in the section descending from 

 the high ground, east of the cross road leading from the old lead- 

 works, in an easterly direction. There the higher ground, over which 

 the main road runs from Pentre Meirig northwards, is composed of 

 the Sutton beds, beneath which the Ehaetic sands and shales crop 

 out in the descent of the road to Cwrt, north of which they are cut 

 off by a fault bringing in the Carboniferous Limestone. 



At St. Mary Hill Common the Sutton Stone has been worked at 



the south side of the Common, west of Terraynydd. The beds are 



slightly conglomeratic, containing fragments of black chert, small 



pebbles of white quartz, and specks of galena, and dip at an angle 



* Ante, p. 24. t Ante, pp. 23 and 27. 



