On the Geological Structure of the Highlands of Scotland. 41 



On leaving Scourie, we pass transgressively over a descending 

 series of hornblendic beds, sometimes micaceous, belonging to the 

 upper part of the series. Sometimes the crystals of hornblende 

 are here two inches in length. At Loch Naclaishfearn the beds 

 are highly micaceous and garnetiferous. At the head of Loch Lax- 

 ford we pass into the lower series, consisting of gneiss, well 

 foliated, of red felspar, quartz and mica. Yeins of pegmatite 

 become more frequent as we proceed, and in crossing Laxford 

 bridge, on the road to Ehiconich, fine sections are laid open in 

 beds of gneiss penetrated by numerous dykes and veins of pegma- 

 tite (a kind of granite), consisting of red orthoclase, crystals of 

 pale yellowish or grey oligoclase, often of large size and showing 

 the fine parallel lines which characterize a tiiclinic felspar. 

 Along with the above are quartz and green mica. The pegma- 

 tite veins traverse the gneiss and schists in all directions, some- 

 times vertically, at other times obliquely, and cross the planes of 

 foliation. They have been noted by Murchison as characteristic 

 of the Laurentian beds ; but it is chiefly in the lower portion they 

 become conspicuous. About Rhiconich, the dip of the beds is 

 southwards or S. S. W., at various angles ; and as this dip was more 

 or less prevalent all the way from Scourie, I estimate that the 

 Laurentian beds must be over 20,000 feet in this district ; — 

 how much more no one can say as the base never appears. 



As we returned to Scourie by sea, we had an opportunity of sur- 

 veying the coast cliffs of red gneiss, and had a fine view of Suilven, 

 Canisp, and Quenaig towards the south, rising from a rugged 

 plateau of Laurentian beds. The horizontal beds and terraces 

 of red sandstone were easily discernible, even at the distance of 

 over twenty miles.* The white dome of Ben More, and its 

 adjoining quartzite ridges of Ben Arkle and Foinaven, bounded 

 the horizon towards the west, while Ben Stack rose above the head 

 of Loch Inchard (Plate X., fig. 4), which we were leaving behind, 

 in the form of a dark shapely cone. Looking northwards over the 

 heaving surface of the Atlantic we could see the islands of Ellen- 

 a-VuUig in the direction of Cape Wrath. 



On the day following (2nd June) we left Scourie and again 

 crossed the North Highlands from sea to sea, reaching the rail- 



* See View of these Mountains in Ramsay's Pliys. GeoL, Gt. Britain, 5 Edit, p. 288. 



