168 H. HICKS ON THE SUCCESSION OF 



extended over it, but that they have been subsequently denuded off. 

 On the west side, as may be seen in Section I. (PL VIII. fig. 2), they 

 form two distinct folds, which terminate on the west coast in a section 

 comprising more than 4000 feet of strata in natural order of succes- 

 sion. Over 3000 feet of the beds in this section have yielded fossils ; 

 and good specimens of Lingulella primceva are found in the red beds 

 near the conglomerates, at Castell in Ramsey Sound. Many, indeed 

 most, of the beds between Ramsey Sound and St. David's are con- 

 siderably altered ; but there are no intrusive masses amongst them 

 of any importance ; the great mass on the east of Ramsey Sound, 

 coloured as greenstone in the Survey maps, is nothing more than 

 bedded Cambrian rock altered. On the east side of the axis the 

 same order of succession occurs as on the west, but the beds are less 

 altered. In the line of the section (fig. 2) it will be seen that they do 

 not repeat themselves as on the west side ; but further eastward they 

 again fold over several times. About 700 feet of the beds in this 

 part of the section have been removed by a fault along the line of 

 the bedding ; otherwise it is similar to the one in Ramsey Sound. 

 The chief places for fossils on the east side are the red beds faulted 

 against the ridge at Porth-clais, and the same beds On the coast 

 near Nun's Chapel and at Caerfai, also the grey flags in the second 

 point west of Porth-clais, where Plutonia Sedgwickii, Conocoryphe 

 Lyellii, Paradoxides HarJcnessi, and other fossils occur. 



The beds of the Menevian group, the next in order of succession, 

 are best seen on the coast east and west of Porth-y-rhaw. A little to 

 the west side of that creek they may be seen resting conformably on 

 the red beds of the Longmynd group, also at Pen-pleidiau, and in 

 Solva Harbour. In Whitesand Bay, on the west coast, they are also 

 found resting conformably on beds of the underlying group. 



The thickness of the Menevian group is about 600 feet; and 

 nearly all the beds are richly fossiliferous wherever found. Litho- 

 logically the Menevian group differs considerably from the Long- 

 mynd group ; but palaeontologically the connexion between them is 

 so strong that it is impossible to separate them by any stronger 

 line of division than as subgroups in a great subdivision. It was 

 on this account that as far back as the year 1867* I proposed that 

 the Menevian and Longmynd groups should be combined together 

 as Lower Cambrian, and that the divisional line should be above 

 instead of below the Menevian, as it had up to that time been 

 placed. 



The next group in order of succession, the Lingula-flag group, is 

 seen resting conformably on the upper beds of the Menevian group, 

 a little to the east of Porth-y-rhaw, and again at Solva Harbour, 

 and near Caerfegg'a ; also on the west coast in Whitesand Bay. The 

 group consists of alternating beds of sandstones and shales, with 

 occasional thick bands of black slates, and it is about 2000 feet 

 thick. It is considerably thinner than in North "Wales ; and very 

 few. fossils have yet been found in it near St. David's. At White- 



* Table of strata, exhibited in the Arts and Science Department of the Na- 

 tional Eistedfodd at Carmarthen, 1867, and Brit. Assoc, Report, 1868. 



