24 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [NoV. 19, 



forming thin beds, often curved and twisted. Near the igneous rock 

 the gneiss is in general very fine-grained, almost compact, and com- 

 posed chiefly of quartz, with a little felspar and minute scales of 

 mica. Many portions seemed almost like the more argillaceous beds 

 in the quartzite series, — in a highly metamorphic state. 



In this section there is thus the same, or rather a more complete, 

 succession of the formations in the same relative order. The red 

 sandstone, resting on gneiss, is covered in ascending order by quartzite, 

 serpentine, and gneiss. The north side of Little Loch Broom ex- 

 hibits these relations even more clearly, as the hills are more pre- 

 cipitous, and the superposition of the quartzite on the sandstone 

 more fully exposed. I had not an opportunity of examining the 

 junction of the quartzite and gneiss in the valley beyond this loch ; 

 but in the fine ridge of Kea Cloch, on its south side, the white 

 quartzite is clearly seen running up over the red sandstone that 

 forms the lower declivities. The red sandstone, dipping at a low 

 angle to the south-east, continues along the coast for several miles, 

 but is at length interrupted by a mass of serpentine or serpentinous 

 gneiss, like that seen rising from below the sandstone mountains near 

 Loch Greinord. Beyond this rock the sandstone, in thin slaty beds 

 of a bluish-white colour, dips at 10° to N., 20° W., forming the outer 

 headland. 



These sections in the centre of the formations may be regarded as 

 typical of the phsenomena in other localities ; but several, both to 

 the north and south, present some peculiarities worthy of notice. 

 One of the most interesting of these is in the vicinity of Loch Assynt, 

 where the precipitous sides of Queenaig, and the other mouiatains 

 that surround that beautiful lake, expose some remarkable sections. 

 I examined these in 1855 with Sir R. Murchison, and had thus 

 the benefit of his former knowledge and experience in determining 

 their relations. Though less clear than at Ullapool, probably from 

 having undergone greater disturbance, the relative position of the 

 formations appears to be essentially the same ; see fig. 3. On the 

 west, towards Loch Inver, the country consists of rounded, gnarled 

 knobs and bosses of gneiss, separated from each other by small 

 lakes and dark moors, and heaped together without any very appa- 

 rent order. Near Loch Inver the gneiss often contains hornblende 

 in place of mica ; and some varieties are a granular compound of 

 felspar and hornblende, containing large imbedded masses of light 

 green fibrous hornblende, some of them two feet in diameter. These 

 hornblendic varieties of gneiss are very characteristic of this formation 

 in the west of Sutherland, as far north as Cape Wrath. On Loch 

 Assynt the gneiss has often its common aspect ; but coarse laminar 

 hornblendic varieties, with no mica, and large nodules of quartz, still 

 prevail. About half-way up the lake, the gneiss, dipping at 55° to 

 the west, is covered by red sandstone, dipping at 5° or 10° to E.N.E. 

 The lower beds of the sandstone are a conglomerate of quartz, felspar, 

 and gneiss ; the largest fragments are about two or three inches in 

 diameter, and not much rounded. Higher up it is a dark, brownish- 

 red, laminated rock, often containing large pebbles of quartz, and a 



