﻿I860.] 



NICOL N.W. HIGHLANDS. 



85 



December 5, 1860. 



William Salmon, Esq., Ulverstone, Lancashire; Peter Higson, 

 Esq., One of H. M. Inspectors of Coal-mines, Broughton, near Man- 

 chester ; John Spencer, Esq., Bowood, Wilts ; Alexander R. Binnie, 

 Esq., C.E., 7 Upper Lansdowne Terrace; George James Eustace, 

 Esq., Arundel House, Clifton Road, Brighton ; F. D. P. Dukinfield 

 Astley, Esq., Dukinfield, Cheshire, Arisaig, W. B., and 67 Eaton 

 Square ; and Thomas Baxter, Esq., 1 Castle Place, Worcester, were 

 elected Fellows. 



The following communication was read : — 



On the Structure of the North- Western Highlands, and the 

 Relations of the Gneiss, Red Sandstone, and Quartzite of 

 Sutherland and Ross-shire. By James Nicol, F.G.S., F.R.S.E., 

 Professor of Natural History in the University of Aberdeen. 



Contents. 



Introduction, and object of paper. j Loch Broom. 

 Durine Limestone. j Loch Maree and Grairloch. 



Loch Erriboll Sections. I Loch Torridon and Loch Carron 



Overlying Red Sandstone and Quartzite 



at Tongue. 

 Loch More Sections. 

 Lochs Grlen Coul and G-len Dhu. 

 Section of Glasven. 

 Structure of Assynt and Ben More. 

 Loch Ailsh Section. 

 Elphin and Craig-a-Chnockan. 



South of Skye. 

 General considerations. 



Distribution of the Rocks. 



Nature of Formations. 



Strike of the Beds. 



Mineral character of the Rocks. 

 Conclusion. 



Introduction. — In a paper read to the Society in 1856, and pub- 

 lished in vol. xiii. p. 17-39 of the Geological Journal, I pointed out 

 some of the features of the Gneiss, Red Sandstones, and Quartzites 

 which form such prominent objects in the geology of the north-west 

 of Scotland. I then proved (contrary to the opinion previously en- 

 tertained) that the Red Sandstone of the North-west Highlands, and 

 especially that of Loch Broom and Applecross, was wholly inferior 

 to the quartzite, which rests on it in an unconformable manner, and 

 spreads out wider to the east. In the same paper I showed that the 

 Assynt and Durness limestone forms the upper member of this series, 

 and that the supposed higher quartzite of Ben More is only the same 

 quartzite rising from under the limestone. In regard to the rela- 

 tion of the quartzite to the eastern gneiss, I stated that, though 

 some of the sections appeared to confirm Dr. Macculloch's view that 

 there are in Sutherland two formations of gneiss — an older below 

 tbe quartzite, and a newer superior to it, — still the presence of 

 intrusive rocks and other marks of disturbance in the sections I had 

 examined rendered this conclusion less certain and satisfactory than 

 might be wished. In order to determine this most important ques- 

 tion, affecting the entire geological history and structure of the 

 north of Scotland, I have subsequently visited this region four times, 



