THE 



GEOLOGICAL MAGAZINE. 



NEW SERIES. DECADE II. VOL. V. 



No. XII.— DECEMBER, 1878. 



o:RX(3-xi<r.A.Xj .a_i^ticl:bs. 



I. — A Possible Explanation of the North Devon Section, 



By Prof. Edward Hull, M.A., E.E.S., F.G.S. ; 

 Director of the Geological Survey of Ireland. 



WHILE engaged this autumn in reinvestigating the relations 

 of the "Dingle Beds" and "Glengarrifif Grit Series" to 

 the Silurian rocks below, and the Old Eed Sandstone above, in the 

 South-West of Ireland, my mind naturally reverted from time to 

 time to the Devonian district, and the succession of its beds, upon 

 which there has recently been so much discussion, and to which 

 the late Professor Jukes devoted so much time and labour. With 

 him I agree in believing that the key to the solution of the De- 

 vonian problem is to be found in the structure of the South of 

 Ireland, though with reference to the actual explanation which 

 he proposed, I can only see my way to a partial concurrence. 



The full and lucid descriptions of the formations of North Devon 

 which we possess are sufficient to enable any one acquainted with 

 the rocks of the South of Ireland to recognize representative beds, 

 even if they may not have visited Devonshire itself. For those 

 who are in this position there are the writings of authors, of which 

 Mr. Etheridge has given a complete summary, and, more recently, 

 those of Professor Jukes and Mr. Etheridge himself. 



Pending a personal visit, I venture to offer a contribution towards 

 the solution of the Devonian problem, which, to some extent, meets 

 the views of recent writers, though somewhat different from any yet 

 proposed. And, in the first place, I may observe that, as far as 

 investigations have yet gone, they have not resulted in discovering 

 the great east and west fault which Jukes supposed to range across 

 North Devon, repeating the red rocks and overlying slates and 

 limestones of Foreland, Lynton, and Ilfracombe. On the other 

 hand, we have the elaborate investigations of Etheridge, both palason- 

 tological and stratigraphical, all going to show that there is an 

 approximately unbroken sequence from the Quantock and Lynton 

 sandstone on the north into the Carboniferous beds of the centre of 

 the country (Quart. Journ. Geol. Soc. vol. xxiii.). 



DECADE II. VOL. Y. — NO. XII. 3i 



