520 Rejjorts and Proceedings — British Association — 



appearance ; and they weather brown and red ; also the slates are of 

 that deep black type, powdering- soot black, and occasionally ribboned 

 with paler bands, so characteristic of the older slate groups of Llan- 

 deilo and Arenig age. Some of the grit beds exhibit curious tortuous 

 structures upon their under surfaces. 



Working in the cliff south of Pen Pistill, Newport Bay, I found 

 a few species of Graptolites, which I hoped would have decided the 

 age of these rocks ; but Mr. Lapworth, who has kindly examined 

 them, writes that they are not sufficiently well preserved for identi- 

 fication, and might be either Lower Llandovery, Llandeilo, or 

 Arenig species. The Dijdograpsiis may be new, and " seems to be a 

 very close ally of D. modestus of the Lower Birkhill Shales." The 

 other species is a Glimacograptiis. 



From the lithological character alone I have no doubt that these 

 beds are not of Lower Llandovery age, but belong to an older group : 

 and this conclusion is borne out by our examination of the northern 

 beds of this grit area, at Cardigan, whose stratigraphical position, in 

 the Middle Bala, we shall prove beyond a doubt. 



Here, around Cardigan Harbour, I found precisely the same kind 

 of rocks as in Newport Bsiy, the grits still pale and highly felspathic, 

 with scattered mica plates, often closely resembling an altered 

 volcanic ash ; and the slates are likewise of the same black type. 

 In these slates, just beyond the little bridge over the stream at the 

 S.W. end of Cardigan town, I found Graptolites which have been 

 determined by Mr. Lapworth as Dicellograptus Morrisii, Hopk., and 

 Diplograpsiis socialis, Lapw. 



Now, Dicellograptiis Morrisii is, as Mr. Lapworth writes to me, 

 "most emphatically a Bala fossil. It is unknown in the Lower Bala 

 (Llandeilo-Glenkiln) beds of either Scotland, Ireland, or Scandinavia ; 

 but it occurs abundantly in the D, Clingani and Pleurograptus linearis 

 zones of the Hartfell shales ; that is to say, on, or not far below, the 

 horizon of the Bala Limestone." " This also is the horizon of D. 

 socialis in Scotland ; D. Morrisii and D. socialis occur associated in 

 the Middle Caradoc beds of Girvan." 



There can, therefore, be no doubt that these rocks are of Bala age, 

 and not Lower Llandovery, and it thus appears that the older slate 

 groups of Llandeilo and Bala age extend up northwards beyond the 

 Priscelly and Llanlawer Mountains, through Newport Bay as far as 

 Cardigan Harbour. Here, then, we have a definite base-line whence 

 we can work northwards, along fine cliff-sections, to the incoming of 

 the Aberystwyth grits, which first appear seven miles off, near 

 Castellbach, south of Llangrannog. 



North of Cardigan the rocks are found soon to become coarser and 

 paler ; massive rolling beds of coarse flaggy slates, some of them 

 arenaceous, and pale splintery slates, being seen in a number of 

 quarries and other small exposures. Bands of " cone-in-cone " nodules 

 and beds of rab and shale are seen S.E. of Aberporth, so that the 

 series, in its upper part especially, comes to resemble the Metalliferous 

 slates of Central Wales. The cliffs north of Abei-porth, tip to and 

 beyond Penhryn, are made up of the same slaty series ; namely, im- 



