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PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



[Feb. 6, 



Loch-alsh. — The promontory opposite Kyleakin has hitherto been 

 mapped as " Red Sandstone," like the hills of Applecross, that is, 

 " Cambrian" according to our classification of these rocks. Next to 

 this red sandstone, there has been inserted on the east side a strip 

 of quartz-rock, beyond which, at Balmacarra, comes the great"gneiss" 

 region of previous geologists*. The red sandstone, however, is not 

 identical with that of Applecross, or the red sandstone of the west 

 coast generally ; indeed, so far as we observed, it is -rarely red 

 sandstone at all, but greyish quartz-rock, which assumes a pink or 

 reddish tint, chiefly on the weathered surfaces. It has an E.S.E. 

 dip at gentle angles. Opposite Kyleakin, indeed, there is a confusion 

 of the bedding, owing perhaps to the prolongation of a fault from 

 Skye, to be immediately noticed ; but east from this the stratification 

 becomes quite regular. The quartzy flagstones, in well-defined beds, 

 dip steadily up Loch-alsh, at from 15° to 20° ; towards Balmacarra 

 House, interlaminations of shale or schist begin to appear ; and these 

 continue to increase, imparting a fissile character to the strata. As 

 we trace the strata still eastward, their schistose structure increases, 

 until, by the diminution of the quartzose bands, and the greater de- 

 velopment of the argillaceous and micaceous portions, they insensibly 

 pass upwards into schists and gneissose rocks ; these range eastwards 

 up Loch-alsh, with here and there a boss of syenite, or felspar-por- 

 phyry. No clearer evidence could be desired, that the quartz-rock 

 or quartzose flagstones graduate in perfect lithological sequence into 

 the upper schists. 



In Sutherland, as stated in former memoirs, the quartz-rock above 

 the Assynt limestone is superposed by another limestone, which, 

 however, is of no great continuity. We failed to detect it in any of 

 the transverse sections of the country between Assynt and Loch- 

 alsh. Along the shores of Loch Duich, however (which is a branch 

 of Loch-alsh), the schists that overlie the upper quartzose flagstones 

 contain, in their lower part, several limestone bands, in the same 

 way as the Sutherland limestone lies between the upper quartz-rock 

 and the superjacent gneissose rocks. 



Loch Duich. — The Loch Duich limestones are best seen along the 

 south side of the fiord. There are at least five or six bands having a 

 general easterly or south-easterly dip. They are separated by talcose, 

 actinolitic, and micaceous schists, often serpentinous like the lime- 

 stones themselves : red felspar-porphyry and syenite also occur in 

 bosses, dykes, and veins. The longest beds of limestone are perhaps 

 those of Totig Point, opposite the village of Dornie and Eilan-Dou- 

 nan ; there they are sometimes pure white, with green serpentine 

 streaks, and have been quarried on the shore f. They range across 

 the hills into Glenelg. 



Red felspathic rocks abound chiefly towards the head of Loch 

 Duich ; they are conspicuous in the hill of Mam Rattachan, and 

 likewise in many of the gullies and clefts worn on the hillsides by 

 the rains, as well as on the shore. We found them also among the 



* See especially Prof. Nicol's map, where these errors are to be seen, 

 t See Quart. Journ. Oeol. Soc. vol. xiii. p. 30. 



