Sughes — Geology of the Lake District. 347 



Professor Sedgwick, in a letter dated 1846, published in Words- 

 wortli's Guide to the Lakes, makes the Coniston Flags the base of the 

 upper group ; but later, in his letter published in 1853, page 242, he 

 says that the determination of the fossils by Messrs. Salter and McCoy, 

 and the agreement in mineralogical character of the Coniston Grits 

 with the May Hill Sandstone, led him to draw the line at the base 

 of the grits, and this classification was followed in his synopsis. 



Professor Harkness and Mr. Nicholson, in a paper read before the 

 Geological Society in May, 1866, say that the Wenlock and Llan- 

 dovery Eocks are unrepresented in the Lake Coimtry, and they refer 

 the Coniston Plags and Coniston Grits to the Upper Caradoc. 



When that paper was read, I stated to the Society my reason for 

 believing that there had been some mistake in the collection of the 

 fossils from the Coniston Flags, and that the fossils, from the 

 presence of which the flags were referred to the lower group, had 

 not come from the beds containing Cardiola interru^ia, and the 

 numerous large Orthoceratites. 



In an unpublished letter, written about that date, Mr. Salter said 

 that he felt sure there were two sets of flags, the one belonging to 

 the upper and the other to the lower group ; and informs me that 

 he had expressed that opinion on various occasions previously. 



The detailed manner in which we are instructed to map the 

 country has enabled me to work out the order of succession of the 

 Silurian rocks along the borders of Yorkshire and Westmoreland, 

 and, I think, to fix the position and nature of the break between the 

 upper and lower group. The result I arrive at is that, " On the 

 evidence, both of mineral structure and of fossils, we are compelled 

 to separate the Coniston Flags from the Coniston Limestone and 

 Calcareous Slates, placing the former at the base of the Upper 

 Silurian series of the Lake district." '■ 



The first Section which accompanies this paper is drawn north-east 

 and south-west along the valley running down from Chapel -le-Dale 

 to Ingleton, and shows the junction of the Green Slates (B.C.), with 

 the Coniston Limestone (B.&.). The beds seen at the north end of 

 the valley are a series of greenish gritty sandstones and slates, which 

 are succeeded by a thick set of coarse grits and conglomerates. Going 

 still south, we cross alternations of greenish slates and tough gritty 

 sandstones for about a mile, when we arrive at the first large quarry, 

 in which a blackish and green slate has been extensively worked. 

 These darker slates are separated from the lighter green and olive 

 slates of the next quarry by alternations of greenish grit and slate. 



This appears to be an ascending section all down the valley. 

 The beds dip at an angle of from 70 to 90 in a south-west direction, 

 and the ascending series varies in lithological character so much that 

 there is nothing to suggest that the beds have been anywhere 

 repeated. On the other hand, there are several large gaps where 

 the section is obscm-ed by drift, and where there might be sharp 

 folds or faults. Faults, where the strata are so highly inclined 

 would have to be very large to produce much efiect on the measured 

 * Sedgwick, 1846, loc. cit. 



