694 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



and grits that repose upon the Upper Old Eed Sandstone of Ireland 

 under the names of Carboniferous Slate, Glengarrifi Grits, &c. are 

 not, or may not prove to be an expansion of, the well-known well- 

 marked typical English fossiliferous Upper Devonian series that 

 occurs on the southern flanks of PickweU Downs &c,, which no one 

 doubts passes insensibly, conformably, and inseparably into the Car- 

 boniferous (Carbonaceous) beds above in that area, where they over- 

 lie and are conformable to the so-called Old Red Sandstone*, which 

 occupies the same position in South Wales and Ireland, but which 

 at its base graduates down (in Worth Devon) through the conform- 

 able and underlying Morte slates into the well-marked Ilfracombe 

 and Combe-Martin series, the Hangman grits, and the Lynton beds 

 below them, all through which a life -succession and physical aspect 

 are determinable, distinct, and readily separable from the beds called 

 Upper Devonian and Carboniferous above. 



When physical facts and fossil evidence can be put forward that 

 will tend to show that the Ilfracombe and Lynton series are not 

 below the Upper Old Red Sandstone of PickweU Down, and are not 

 the Lower and Middle Devonian, by an assemblage and facies of 

 recognized organic remains as zoologically distinct as the Carboni- 

 ferous are from the Permian which succeed them, and not till 

 then, can any new reading be proposed for the physical structure of 

 North Devon. 



After very careful investigation into the physical structure of 

 North Devon, as well as a critical examination of the organic remains 

 contained in its diversified rock-masses, I can come to no other con- 

 clusion than that the series of sandstones, slates, and limestones 

 ranging from the Poreland and Lynton on the north to Pilton and 

 Barnstaple on the south are one great and well-defined system, and 

 equally well divisible into three groups, a Lower, Middle, and Upper 

 Devonian series, each equally weU characterized by a fauna, the 

 zoological facies of which are sufiiciently distinct to determine them 

 one from the other. Let this Devonian system be equated to what 

 it may, it is nevertheless a great life-group — a system based upon 

 clear stratigraphical succession of strata and an associated and well- 

 marked marine fauna. This is borne out and testified by its extended 

 and equivalent groups in Europe, where in Nassau, Rhenish Prussia, 

 and Belgium the Lower and Middle series are precisely the same as 

 our own in North and South Devon. 



In Great Britain, the North-Devon mid West- Somerset rocks must 

 be regarded as the types with which we must compare those of South 

 Devon and the Continent ; for here only can the succession be satis- 

 factorily determined ; and although the preservation of the fossil fauna 

 is more obscure than in the south, still every day adds to its com- 

 parative completeness, and to the identity of the two areas. 



In North Devon and West Somerset only do we get the lowest 

 known beds ; and although these are much obscured by the Lynton 

 anticlinal, and perhaps an extensive fault afl'ecting the Eoreland sand- 

 stones, it is clear that no fossil-bearing slates or limestones underlie 

 * Not the whole, but the "Upper." 



