Prof. Hull — On the North Devon Section. 531 



above — that the Dingle Beds and Glengarriff Grits are really the 

 highest members of the Upper Silurian Series, and altogether dis- 

 connected from the true Old Red Sandstone. To this question I 

 hope to return on a future occasion. 



Eeverting, however, to the Devonshire section, I must also assume 

 that the " Pickwell Down Sandstones " are the representatives of 

 the true " Old Eed Sandstone " of the South of Ireland. They are 

 described as consisting of red micaceous sandstones, shales, and con- 

 glomerates, a description which would answer fairly well for the for- 

 mation representatives of which I suppose them to be. Mr. Etheridge 

 calls it the " Upper Old Red Sandstone," and possibly the upper- 

 most beds at the junction of the " Baggy and Marwood slates 

 (Cucullsea Zone) " may represent the formation of this name in 

 the South of Ireland ("the Yellow Sandstone" of Griffith) with 

 Coccosteus, Anodonta JuJcesii, and Adiantites Hibernica. Jukes men- 

 tions some beds near Drayton and Slade, which strongly reminded 

 him of the Kiltorcan beds of this stage in county Kilkenny. It 

 will probably be found on a careful resurvey of North Devon, that 

 the Pickwell Down Sandstones are somewhat unconformable to the 

 underlying beds. 



Assuming the identity in position of the Pickwell Down Sand- 

 stones with the Old Red Sandstone of Ireland, it follows that the over- 

 lying Marwood slates and Pilton Beds, consisting of slates, sometimes 

 calcareous, with bands of limestone and sandstone, characterized by 

 Gucidlcea trapezium, etc., are the representatives of the " Lower Car- 

 boniferous slate and Coomhola grits " of the South of Ireland ; and 

 in this identification, I have much confidence that Jukes was perfectly 

 correct. If anything was required to confirm it, we have the plant 

 evidence in the presence of Lepidodendron and Calamites in Sloly 

 quarry. The general representative sections of the rocks in the 

 South of Ireland and in North Devon, according to the above 

 interpretation, would therefore be as follows (see table at the end of 

 this article, p. 532) : — 



Should it ultimately appear that this classification is correct 

 — or approximately so — it will be found to confirm the views of 

 those geologists who consider that there is a general ascending series 

 from the Coast of North Devon, beginning with the Foreland and 

 Quantock Hill group, and terminating with the Culm-measures and 

 Barnstaple Beds. On the other hand, it will confirm Jukes's views 

 regarding the Carboniferous age of the so-called " Upper Devonian 

 Beds " from the Baggy and Marwood slates upwards, and also his 

 determination regarding the age of the " Pickwell Down Sand- 

 stones." It also explains the unconformity between the Old Red 

 Sandstone and "the Dingle Beds " — so remarkably prominent in the 

 Dingle Promontory— and it determines the relations between the 

 Marine Devonian Beds and the Old Red Sandstone in Devonshire. 

 In oiTering the above observations towards the solution of the 

 question, and pending a personal inspection of the North Devon 

 beds, I would, meanwhile, invite the opinion of those geologists 

 who have the advantage of knowing Devonshire already. 



