1856.] NICOL — QUARTZITES, ETC. OF N.W. SCOTLAND. 25 



few traces of blue carbonate of copper. The sandstone is covered by 

 the quartzite, the first beds being a coarse grit, with fragments as 

 large as peas ; and those higher up, a fine-grained white stone with 

 a vitreous lustre. At Skiag Bridge, where the road turns north to 

 Kyle Scow, the quartzite is of a red colour, and contains numerous 

 cylindrical bodies, like those noticed near Ullapool. Ascending the 

 hill by this road, we found brown slaty beds, with fucoid or plant- 

 like impressions ; and higher up again a bed with cylindrical bodies, 

 thus identifying the strata with the Loch Broom rocks. On the 

 Hne of section along the lake, the quartzite is succeeded by limestone, 

 generally of a white or blue colour, and with a fragmentary or brec- 

 ciated structure. Near Stronchrubie, east of the inn at Inch na 

 Damph, the same limestone is well seen, ranging along the fine pre- 

 cipitous cliff. In this place it is often cherty, containing masses of 

 siliceous matter like those common in the mountain-limestone, and 

 also druses lined with quartz-crystals. Large lumps or masses of 

 red felspar also occur in it ; and a bed of greenstone, of augite and 

 dark-red felspar, runs along the face of the cliff. The quartzite 

 with cylindrical bodies again crops out at the bottom of the escarp- 

 ment below the limestone, so that the whole series has probably been 

 brought up by a fault. In the hills behind, according to Mr. Cun- 

 ningham, the limestone is again covered by quartz-rock, as drawn in 

 the section ; but this locality I did not visit*. 



This section is evidently identical with that on Loch Broom, both 

 in the mineral character and relative position of the beds. The 

 only difference is in the apparently greater thickness of the lime- 

 stone, and in this being again overlaid by quartzite. As on 

 Loch Broom, also, the quartzite is unconformable to the red sand- 

 stone, and dips at a higher angle than the rock on which it rests. 

 This is well seen on the south side of Queenaig, where the white 

 quartzite creeps up, as it were, gradually over the red sandstone beds. 

 The flank of the mountain on the south side of Loch Assynt, towards 

 Canisp, exhibits the same arrangement. The gneiss on the west side 

 is overlaid by nearly horizontal sandstone beds, which are in turn 

 covered unconformably by quartzite, sloping down to the east at 

 20° to 30°. The relation of the quartzite to the gneiss, bounding 

 it on its eastern side, was not visible on the line we followed, as a mass 

 of red felspar-porphyry intervenes near Loch Borolan. This rock is 

 not unlike some portions of the Loch Broom serpentine, thus adding 

 to the analogy of the two sections j*. 



On the north dechvity of Queenaig the quartzite again appears, 

 resting unconformably on the red sandstone ; but the relations of the 

 formations are obscure, probably from some fault near the line of 

 junction. In Loch Glencoul the superposition of the quartzite to the 

 red sandstone is very distmct, and both rocks are seen dipping away 

 under the huge mountains on the east. In the recesses of this loch, 



* Probably it is only the lower quartz, brought up anew by a fault. 



t Mr. Cunningham states, p. 96, that the quartzite of Ben More rests uncon- 

 formably on the gneiss. The relations of this quartzite, both to the gneiss and 

 to the limestone of Stronchrubie, require further investigation. 



