Presidential Address—The Geology of Devon. 509 
be regarded as the base. It is only in recent years that this uncon- 
formity between the Lower and Upper Old-Red Sandstone has been 
fully recognized. Moreover, this is by no means a local phenomenon 
confined to the Welsh districts, since in the South of Ireland there 
is a great hiatus between the presumed equivalents of the Pickwell 
Down beds above and those of the Lynton beds below. Thus both 
in the South of Ireland and in South Wales the time representatives 
of the Ilfracombe and associated beds are absent. These three 
districts are more or less involved in the great post-Carboniferous 
east-and-west folding, and may be said to belong to the same 
system of physical disturbance. But even in Scotland Hugh Miller’s 
Old-Red Sandstone is found to consist of two ‘portions, the lower 
part shading off into Silurian, the upper into the Carboniferous. 
Thus, throughout the British Isles, what was formerly known as the 
Old-Red Sandstone is found to consist of two very distinct members, 
widely separated from each other in point of time, each having 
affinities with the neighbouring system. If, then, the case rested 
on the Old-Red Sandstone alone, its fate would only differ from that 
of Poland in being partitioned between two instead of three ambitious 
neighbours. 
Having learnt thus much with regard to the Old-Red Sandstone, 
it is now time to return to North Devon, where we have a fossiliferous 
series interposed between beds which are held to be the equivalents, 
mutatis mutandis, of the Lower and Upper Old-Red Sandstone re- 
spectively. It is these fossiliferous beds which forge the link that 
was missing, whilst the intermediate yet independent character of 
their fauna justify, on paleontological grounds, their being regarded 
as the head-quarters of a distinct and separate system. The more 
copious development of the remains of marine organisms in the 
corresponding beds of South Devon further justify the original 
determinations of Lonsdale. It is these central beds, therefore, 
which constitute the backbone of the Devonian system; and if the 
correlations to which I have alluded be substantiated, they must 
carry with them the Upper and Lower Old-Red Sandstone as integral 
parts of that system. 
It seems to be generally admitted that the Pickwell-Down beds 
are really the equivalents of the Upper Old-Red Sandstone. Perhaps 
it was Professor Hull who first suggested this, but nearly ten 
years ago Mr. Champernowne, whilst agreeing that the Pilton and 
Marwood beds should be referred to the Carboniferous, considered 
the Pickwell-Down Sandstone to be true Old-Red Sandstone, and 
also Upper Devonian. The fact of the Pickwell-Down beds being 
unfossiliferous lends additional probability to this view. The 
correlation of the lowest Devonian beds with the Lower Old-Red 
Sandstone seems more open to discussion. In the first place the 
subject is complicated by the suggestion that the Foreland and 
Hangman Grits are repetitions of the same beds by means of 
faulting, and secondly the arenaceous beds of the Lower Devonian 
in North Devon yield some marine mollusca. The resemblance of 
the Foreland Sandstones to the Glengariff Grits was regarded by 
