160 



If these hints be of any use I shall rejoice. I shall very soon be called off to 

 Scarborough to consult the doctor, so I write in much hurry. 



You tell me about your Scotch axis, the South side of which you suppose may 

 match with the North side of Cumberland. "Where and what is your axis ? 

 I never found it ; and I had promised to go with Professor Rogers to seek it. 

 Murchison, I think, told me that Professor Nichol had found it ; but I forget 

 where. In 1848 I made some traverses through the S. chain of Scotland, and 

 collected from the "Moffat Group." I once thought it might represent a part of 

 the great Skiddaw Group ; but I now doubt it very much, and I would rather 

 provisionally place it at the base of the Lower Bala Group* where there is in 

 Wales a great deposit of dark slates, here and there with many graptolites. 

 Over the Moffat Group comes on a great arenaceous and slaty group which I 

 think undoubted Upper Bala, with one well known calcareous band, and 

 overlaid unconformably by the Old Red Sandstone. 



Below the Moffat Group I placed a hard, old-looking, arenaceous and slaty 

 group (such, for example, as that which runs out in Barrow Head), but I 

 wanted good sectional evidence, so my sections were only hypothetical, and the 

 most stupid and mischievous of all proceedings is to name the groups and give 

 them a definite place before we know the sections. I am still a little sceptical 

 about your Wenlock Beds at Balmae. My fossils from them do not settle the 

 point at all. If, however, the old published list be correct, they must be 

 Wenlock twisted up in the contortions of the older rocks. I fully expected in 

 1848 to have found overlying true Silurian rocks towards Barrow Head. I ran 

 down there for one day, and, of course, saw no Silurian rocks. For any 

 information on this point I shall be thankful when you write to me. 



On the N. side of the Cambrian cluster we have : — 



1. Skiddaw Slates of vast thickness and complexity of structure. 



2. Green Slates and Porphyry • • • in thickness, and (?) coming to 

 an edge. 



3. Old Red Conglomerate in patches, and not continuous. 



4. Carboniferous Limestone. 



5. New Red Sandstone. 



So that we often have the Carboniferous Limestone lying immediately in the 

 Skiddaw Slates, and on the N.W. side of Cumberland this is always the case. 

 How this can match with the formations on the N. side of the Solvvay Firth is 

 more than I can see at present. 



I must conclude, for my friends are tired of waiting for me. Accept my best 

 wishes for your honour and success in your pursuits ; — my power of work is 

 very nearly over. But for this suppressed gout I should long since have told 

 the pubhc all I wish to tell ; but I must conclude. 



Very truly yours, 



A. SEDGWICK. 

 * I wish to direct special attention to this remark ; the italics are Sedgwick's.— J.G.G. 



