298 J. O. Goodchild — The Coniston Limestone Series. 



case in the Girvan area. Certainly the two Corona beds do not 

 come together, as Mr. Marr's sections indicate. 



As for the relation of these Helton Moor beds to the interesting 

 set of strata discovered by Messrs. Marr and Nicholson at Drygill, 

 I fail to see any reason why they may not be contemporaneous. It 

 is now several years since I expressed the opinion that the higher 

 Ordovicians of Cumberland were transgressive across successively 

 lower beds of the same system as they trend towards the north ; 

 and illustrated that view by a diagi-am (Proc. Geol. Assoc, vol. ix. 

 No. 7, fig. 1). This diagram was intended to express what I believed 

 to be the facts in not only the Lake District, but also in the Cross 

 Fell area- 

 It may be convenient to give here a general summary of the 

 succession of these older rocks as developed in the area at the foot 

 of the Cross Fell Escarpment : — 



Approximate 

 Silurian Rocks. thickness 



Unconformity. in feet. 



Coniston Limestone Series + 900 



Dufton and Yarlside Ehyolitic rocks +1100 



Strata missing, probably not of great thickness. 



Helton Moor (? and Rake Brow) Volcanic Series +1000 



Helton Moor Shales + 600 



Rreak of unknown extent, probably coinciding with an un- 

 conformity, which increases in extent going northwards. 



Milburn Rocks not less than 6500 



Skiddaw Slates, of great thickness not less than 8000 



The Craven Area. — I shall not attempt, on the present occasion, 

 to deal with the many difficult problems suggested by the Bala rocks 

 of this area. All the older Palaeozoic rocks of Craven were mapped 

 in great detail by Prof. Hughes, and were described by him, many 

 years ago, and both Mr. Marr and I owe much of our knowledge of 

 them to his earlier work. I may, however, state that they seem to 

 me to be much more complex, and also very much thicker, than has 

 generally been supposed. It is a long way from Roman Fell to 

 Wharfe ; otherwise I should be disposed to think that the beds in 

 Craven that Mr. Marr has taken to be on the horizon of the Coniston 

 Limestone are much lower down in the series, and that the true 

 Coniston Limestone (here much thicker than in the typical area) was 

 locally denuded (together with a great thickness of some rocks older 

 in the series) before the Silurians were laid down ; so that it is only 

 left here and there. I had the advantage of going over all the details 

 of that part of Prof. Hughes' work under his own guidance, and 

 with the additional advantage of the long experience of Mr. Aveline. 

 This was between 1874 and 1876. Later still, my colleague, Mr. 

 Gunn, carefully checked all our previous work, under the super- 

 intendence of Mr. Howell, the Director for Great Britain. I think 

 I may now venture to state on behalf of all my colleagues concerned, 

 that not one of us is at all disposed to entertain for a moment the 

 idea that the Bala rocks of Craven are separated from the Ingleton 

 Green Slate Series by a fault, as Mr. Marr has shown in his section. 

 On the contrary, the Bala calcareous-and-ashy series appears to us 



