72 PEOCEEDINGS OF THE GEOLOGICAL SOCLETY. [DeC. 6, 



These beds represent the black shales and argillaceous limestones 

 above the bone-bed at Penarth, &c. 



The abundance of silica and comparative scarcity of calcareous and 

 aluminous matter here, as compared with the sections of Penarth or 

 the west of England, is noticeable ; the explanation no doubt lies in 

 the proximity of this series to or upon the Palaeozoic rocks of Car- 

 marthenshire, Brecknockshire, Cardiganshire, and North Wales, with 

 their sandstones and grits. 



Though a fault is now the boundary of the Khcetic series north- 

 wards, it perhaps nearly corresponded with the shore of the Ehsetic 

 sea, the rivers running into which drained large Palseozoic areas. 

 That the water was shallow is probable from the varied conditions of 

 the bedded sandstone in a small area round this district ; moreover 

 the abundance of sand and not mud shows the probable deposition 

 near a shore. That it coincided with some shore and system of 

 islands at the close of the Bunter period we know from the disposi- 

 tion of the Magnesian Conglomerate in this area. 



We may suppose that there has been no great extension either of 

 the Eh^tic or Keuper series northward on the Coal-measures ; or 

 more cases similar to that described by Sir H. de la Beche near 

 Bridgend, of Trias resting on Coal, would have occurred. The great 

 denudation of the Coal-measures took place before the deposition of 

 the secondary rocks here ; and perhaps denuding forces have been 

 comparatively passive since. 



4. Keuper near Bridgend. — North of Bridgend, one mile and a half 

 on either side of the river Ogmore, are white Keuper sandstones 

 showing very similar characters to some of the Avicida-contorta 

 sandstones : these yield a stone well fitted for architectural purposes, 

 being soft but durable. At the quarry here there are 25 feet of pale- 

 green or white Keuper sandstones capped by 6 feet of green sandy 

 marls (Ehsetic ?). These sandstones must be at the base of tho 

 Keuper. 



5. Sutton Stone. — I come now to the consideration of the Sutton 

 Stone. This is spoken of by Sir H. De la Beche * as a " whitish 

 variety of the Lias." He notices that it commences with a white 

 conglomerate enclosing pebbles of Carboniferous Limestone, upon 

 which formation the Sutton Stone is seen to lie, and particularly 

 well on the coast between Sutton and West farmhouses, and again 

 at Dunraven Point. He notices the grey Lias above these beds, and 

 draws attention to the conglomeratic character of the Lias around 

 Langan. 



These beds I now claim as Khsetic, and would unquestionably 

 separate from the Lias. As developed on the coast, they are between 

 80 and 90 feet in thickness: to the lower half of this the term 

 " Sutton Series " may apply ; and for the upper half I propose the 

 name of " Southernclown series," as they are best seen in the fine 

 cliff- exposure under the hamlet of Southerndown. 



6. Sutton Series. — The term " Sutton Stone " is generally applied 

 to the white and softer beds or freestones which are used for architec- 



* Loc. cit. p. 272. 



