﻿1861.] 



MURCHISOK AND GEIKIE HIGHLANDS. 



189 



scenery of the Loch Ned Valley affords another excellent illustration 

 of how closely the physical aspect of a country is linked with its 

 geological structure. 



Beyond the head of Loch Ned the glen bifurcates, — the eastern part, 

 or that to the left, leading to Loch Vrin, and thence to the Ullapool 

 road at Fascrianach, while the western branch ascends by the Beal- 

 loch-na-Cros to Loch-na-Fad. The latter glen has been deeply cut 

 by a mountain-torrent ; and its sides are likewise scarred and grooved 

 by watercourses, which, though usually dry, or nearly so, are rapidly 

 filled by the rains which sweep down the dechvities, leaving the 

 bottom of the pass strewn with debris. Red felspar is here espe- 

 cially abundant, mingled with a dark chloritic gneissose rock. 



Ascending to the summit of the Bealloch-na-Cros, over heaps of 

 rubbish in which felspar fragments are especially numerous, we 

 have a wide view of the surrounding mountainous ranges. The 

 rocks on either side have a decided easterly dip on the sides of the 

 glen and along the slopes of the adjacent hills, especially those which 

 encircle the gloomy Corry Yichkerracher (Farquhar's Corry). The 

 sheet of water called Loch-na-Fad lies before us. Beyond it, to the 

 west, rise the enormous masses of Cambrian sandstone and Lauren - 

 tian gneiss that form Sleugach and the neighbouring mountains 

 which shoot up from the depths of Loch Maree. 



A little on the west side of the upper part of the bealloch, a ravine 

 exposes the white quartz-rock, dipping a little north of east, at 

 10-15°. From this point to Loch-na-Fad, the descent lies over 

 mounds of debris of white quartz -rock and red felspar. Both these 

 rocks protrude in detached hummocks and knolls. Near the lake, 

 the felspathic rock becomes serpentinous, and we then, at the south 

 end of the lake, come upon a limestone of considerable thickness, 

 dipping to the north-east. "We were informed that limestone was 

 worked at the north end of the loch, at a place called Glen Tulloch, 

 but not in so thick a bed as that of Loch-na-Fad. The latter we 

 regard as a continuation of that seen in Glen Cruchalie, which will 

 presently be described. 



That this limestone occupies, on the whole, the same horizon as 

 that of Ullapool, Drumdrynie, and Assynt, can hardly be doubted. 

 The amount of drift by which it is surrounded, however, does not 

 admit of a close examination of its junctions with the adjacent rocks ; 

 while the time at our disposal proved much too short for such a 

 scrutiny as this portion of the line of outcrop deserved. It is quite 

 possible that there may be some faulting here, and even to a con- 

 siderable extent, though the general order of succession remains 

 sufficiently clear. The metamorphism which is often most intense 

 in the vicinity of a limestone is conspicuous here. The serpentine 

 increases as we approach the calcareous beds ; and, did the drift- 

 covered surface permit, we might in all likelihood find the one rock 

 passing insensibly into the other. 



Below the limestone lies the usual white quartz-rock, creeping 

 up the acclivity on the west side of the loch, with a gentle north- 

 easterly dip. The lake empties itself by the River Hassac, which, 



