52 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [DeC. 3, 



Should any one ask, whether still higher groups, such as the 

 Coniston grits and the Ireleth slates, may not be represented among 

 the rocks laid bare in some of the valleys of denudation connected 

 with the Ribble, 1 could not satisfactorily answer the question. 

 For I know little of the sections on the east side of the Ribble ; 

 and there is a large spread of slate rocks (laid dowu by Phillips) 

 in the lateral valley of Stainforth, which I have not visited for 

 more than thirty years. And the slate-rocks break out again (as 

 I have been informed) in the denudations between Malham Tarn 

 and Kilnsea, in a mountain-tract I have never visited. Again, 

 it might be asked whether the flagstones of the Ribble, vdth their 

 great alternating beds of hard grits {calliards), might not represent 

 both the Coniston flags and the Coniston grits? To such a question 

 I might reply, that, while on the spot, I gave it what I thought a 

 fair trial ; and that the evidence of the sections seemed to disprove 

 the supposed union of the two deposits ; for the calliards appear to 

 abound quite as much in the lower as in the upper part of the great 

 flagstone group. 



With every wish to avoid unnecessary details, I must shortly notice 

 some remarkable beds seen (nearly on the line of section) in the 

 flagstone group on the west side of Moughton Fell. We there find 

 (alternating with the harder grits) a kind of whet-slate or flagstone 

 which is divided into rhombohedral solids by two sets of cross-joints. 

 Many of these regular solids have undergone a partial decomposition 

 shown on the planes of fracture by beautiful coloured rings (exactly 

 like those occasionally seen in flint-pebbles) ; which, commencing 

 irregularly at the outer surfaces, gradually become more symmetrical 

 as they diminish in size and approach the centres of the several solids. 

 The same kind of decomposition, marked by rings of colour, has 

 affected some large masses of the Skiddaw slate, and produced co- 

 loured lines which might easily be mistaken for the original marks of 

 bedding. And similarly deceptive lines of colour (derived from a 

 decomposition that has commenced from the joints sometimes tra- 

 versing masses of considerable size) may be seen, though rarely, among 

 the Ireleth slates, and the Silurian flagstones of Leintwardine. 



A valley of denudation separates the tabular calcareous cap of 

 Moughton Fell from a corresponding tabular cap that ranges N. and 

 S. from Austwick towards the base of Ingleborough. I had no oppor- 

 tunity (during my last visit) of examining the slate-rocks in the valley 

 between these tabular hills ; which I the more regret, as I have been 

 informed by John Ruthven that calcareous slates, with organic re- 

 mains, were laid bare in some quarries or excavations that were opened 

 a few years since near the village of Austwick. Provisionally, there- 

 fore, I consider the Coniston limestone as reappearing in the section 

 under the calcareous ridge near the village. This point might, per- 

 haps, be ascertained by a careful exiamination of the sections in the 

 neighbouring watercourses. But my time was gone, and I had not 

 a single hour to devote to this examination ; and the excavations near 

 the village, to my great disappointment, were all filled up. 



The remaining part of the section crosses the Craven fault , which 



