154 



MR. F. R. COWPER REED ON THE GEOLOGY OP [May 1 895, 



coast-sections between Fishguard and Newport I have failed to find 

 any fossils, and inland my search has been successful in only a 

 few instances. 



The lowest beds in the district are the slates between Goodwick 

 Bay and the Pwll Ceunant — Llanllawer fault. These occupy ap- 

 proximately all the ground south of Fishguard town. They are 

 black to bluish-black tough slates, splitting into fairly large slabs. 

 Since in the upper portion of these slates Llanvirn fossils have been 

 obtained, in quite the northern part of their area, it follows that, 

 unless there is repetition by folds or faults, the greater part belongs 

 to the Arenig series. The principal locality at which fossils have 

 been found in these beds is in the Blaen y Delyn quarries and on 

 the adjoining slopes, close to Tower Hill, Fishguard. On beds of the 

 same age stands the town of Fishguard itself. The strata on this 

 horizon have suffered considerable plication, and the small folds and 

 faults can be seen on Tower Hill. To this cause may be attributed 

 the slight admixture of fossils from this locality, for Didymograptus 

 Murchisoni is extremely abundant together with Lower Llanvirn 

 (Upper Arenig) forms. The identical appearance of the beds and 

 their mode of preservation make the faunal facies the only means 

 of separating the horizons. The fossils obtained from this locality 

 are the following : — 



Orthoceras caerersiense (Hicks). 



„ Avelinii (Salter). 



Caryocaris Marri (Hicks). 



,, sp. (Salter). 



Ceratiocaris, sp. 



Placoparia cambriensis (Hicks). 

 JEglina binodosa (Salter). 

 Illanus, sp. 



Didymograptus Murchisoni (Beck). 



„ „ var. ye- 



minus. 



„ bifidus (Hall). 



Diplograptus dentatus (Brongn.). 

 Climacoyraptus ccslatus (Lapw.). 



„ sp. 



"We seem to be just on the junction of the Lower Llandeilo 

 ( = Upper Llanvirn) and Llanvirn ( = Lower Llanvirn of Dr. Hicks) 

 Beds ; for most of the graptolites belong to the former, while the 

 rest of the fossils belong to the latter. The graptolites were 

 determined by Mr. J. E. Marr, F.B.S. The ' tuning-fork ' forms 

 are especially abundant. 



The age of the beds is definitely fixed by this assemblage of 

 fossils, and they are evidently a continuation of the well-known 

 Llanvirn and Lower Llandeilo Beds of St. David's, first described by 

 Dr. Hicks. 



On the strike of these Tower Hill beds exposures of slates of 

 similar character occur on the roadside, 200 yards west of the 

 farm of Maes Gwynne, on the way to Manorowen from Fishguard. 

 The graptolites from these beds were submitted to Prof. Lapworth, 

 who very kindly gave me his invaluable assistance in identifying 

 these badly-preserved fossils. He distinguished three forms : — 

 Didymograptus Murchisoni, var. geminus, Cryptograptus tricornis 

 (Carruthers), Diplograptus foliaceus (Murchison), 1 adding : ' These 

 beds are well below the Llandeilo Limestone, and answer to the 



1 This fossil Prof. Lapworth identifies as J), foliaceus, ' or, at least, a form 

 which I cannot separate from one of the Llandeilo varieties of the species.' 



