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PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



[Dec. 5, 



and examined all the principal sections and almost the entire tract 

 of country from the north coast of Sutherland, to Loch Alsh and 

 Skye in the south, and from Caithness on the east to the Lewis on 

 the west. I now propose to lay the results of these investigations 

 before the Society, as confirming or correcting the views given in my 

 former paper. This is the more necessary, as, whilst some of my 

 statements have been controverted, other statements may seem to 

 support conclusions which I now feel assured are erroneous. The 

 wide region over which these observations extend, and the great 

 importance of the questions involved, together with the weight of 

 authority opposed to the views I support, must form my excuse for 

 the length of this paper and the full details given of some sections. 



Object of this paper. — As it may render the bearing of the special 

 sections noticed more evident, I may state that there is no difference 

 of opinion in regard to the first part of the series of formations as 

 established in rny paper of 1856. All observers now admit that there 

 is only one great formation of Red Sandstone on the north-west coast, 

 resting unconformably on gneiss, and covered, in many cases also un- 

 conformably, by quartzite, and this by the fossiliferous limestone of 

 Durness. But the further order is matter of discussion. I regard 

 this limestone, in Durness, Assynt, Loch Broom, and Loch Keeshorn, 

 as the highest member of the older formations in this region (fig. 1 ). 



Fig. 1. — Diagram -section of Sutherland and Boss. 



d. Limestone. c". Fueoid-beds. c 1 . Quartzite. b. Red Sandstone. 

 a. Crystalline schists. x. Granulite or syenite. f. Fault. 



On the other hand, it has been affirmed* that it is overlain by an 

 upper quartz-rock and limestone, and that these are in turn " clearly 

 and conformably covered," or " followed symmetrically upwards, by 

 mica-schists, flagstones, and a younger gneiss." This paper is 

 designed to prove that no such clear, conformable, or symmetrical 

 upward succession is to be found, but that the line of junction, 

 where this conformable succession is said to occur, is clearly a line 

 of fault, everywhere indicated by proofs of fracture, contortion of the 

 strata, and powerful igneous actionf . 



Dunne Limestone. — Beginning our sections in the north, the first is 

 that of the Durine limestone. The section given in my former paper J, 

 though showing the true general relations of the beds, must be cor- 



* Sir R. I. Murchison, ' Siluria ' (3rd edition), p. 553. See also Murchison 

 " On the Succession of the Older Rocks in the Northernmost Counties of Scot- 

 land," Quart. Journ. Geol. Soc. vol. xv. p. 352, and " Supplemental Observations," 

 ib. vol. xvi. p. 215, &c. 



t The diagram fig. 1, compared with the similar section fig. 2 in p. 217 

 of toI. xvi. of Quart. Journ. Geol. Soc, will bring out this difference of views 

 more clearly. 



\ Quart. Journ. Geol. Soc. toI. xiii. p. 23. fig. 5. 



