512 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



liaving- cliiefly confined my attention to the South Wales coast, where 

 the beds of the Sutton and Southerndown series occur — in connexion 

 with the age of which I am compelled to differ from the conclusions 

 arrived at by Mr. Tawnc}', who has suggested their being of Ehcetic 

 or even of St. Cassian age. 



1. Penartli Hhcetic and Liass'w Section. — The most important sec- 

 tion showing the llhaetic series is that of Penarth Head. In general 

 this formation is more feebly represented in Wales than in most of 

 the Somersetshire deposits ; this is more especially the case with the 

 *' White Lias," which, though so constant in the latter county, is 

 frequently scarcely recognizable in the Welsh sections. 



At the base of the Penarth section are thickly bedded gypseous 

 red marls of the Keuper, above which the Avicula-coyitorta beds 

 come in, but, from the difficulty of getting access to them, are not so 

 readily to be studied as the Ehsetic sections given at Camel, Shepton 

 Mallet, and Hatch. The "White Lias" seen opposite the Docks, 

 instead of being composed of thickly bedded limestones, is repre- 

 sented by grey shales about 30 feet thick, and contain only two 

 beds of 3 inches of White Lias stone. In the limestone quarry 

 above, west of the cliff, a fine section of the Lower Lias series may 

 bo seen, at the base of which occur about twenty beds, which 

 represent the Ostrea and " Pirestone" divisions of Camel, and in the 

 upper of which are numerous Ostrea liassica, PKcatuIa acuminata, 

 and Lima gigantea. These are succeeded by thirty-six other beds, 

 with Ammonites planorhis, Lima gigantea, L. duplicata, L. tuhercu- 

 lata, and Pecten Pollux. 



In this section the Liassic beds have been deposited beyond the 

 Carboniferous Limestone coast-line, and, having their usual sequence 

 through Keuper and Ehsetic formations, are undistinguishable from 

 the Somersetshire beds ; and it is not improbable that the same unifor- 

 mity previously noticed might on close examination be pointed out. 



2. Bridgend Liassic Sections. — A reference to the Geological 

 Survey Map shows an almost uninterrupted development of the 

 Lower Lias on the South AVales coast, from Penarth to Sutton and 

 Southerndown ; and there is in this direction the last westerly 

 extension of this formation. The coal-basin on the south-east is 

 bounded by continuous Old Red Sandstone and Carboniferous Lime- 

 stone. As these rocks come to the south of the basin, they are 

 much broken, and present numerous basins in which jN^ew Hed 

 Sandstone, Conglomerates, and Liassic Beds have been enclosed, and 

 there is again repeated the phenomenon, noticed on the Men dip coast- 

 line, of later beds deposited on a sea-bottom of Carboniferous Lime- 

 stone. One of these may be seen in what may be termed the 

 Bridgend and Brocastle basin. A few miles to the north the long- 

 extended escarpment of the uplifted Coal-measures, to the base of 

 which the above Secondary rocks reach, may be observed. The Lias 

 within this basin is cut off from its larger development towards the 

 coast, except by a narrow neck of that formation passing between 

 projecting ranges of Carboniferous Limestone between Brocastle and 

 Ewenny. The Lias from this point inclines slightly towards the 



