KOCKS OF THE NOETHEKN HIGHLANDS. 381 



mostly green, the rock being of precisely the same character as the 

 grit in the peak of Coniveall. 



Section up the Cascade from Dhuloch Beg. — The lower part of the 

 burn, just above the Oykel river, is occupied by drift and bog. 

 The lowest rock seen is a slight outcrop of gneiss, dipping E.N.E. 

 at 45°. Above this is green grit, with, in one place, the red variety, 

 the total thickness being a little under 100 feet. Towards the 

 upper part the rock becomes coarser, small pebbles coming in, then 

 larger ones, till at the top we reach a massive conglomerate, undis- 

 tinguishable from the rock which lies at the base of the grit in 

 Coniveall. The larger pebbles, which are of highly altered quartzite, 

 are from 6 to 8 inches in diameter. Some of the smaller ones are 

 a granitoid gneiss, similar to ordinary Hebridean. This conglo- 

 merate dips E.N.E. at 30°, and is overlain by gneiss dipping E.N.E. 

 at 40°. The two rocks are in immediate contact, the conglomerate 

 being a little crushed and contorted. The gneiss can be traced up 

 literally without a break into the massive gneiss of the southern 

 ridge of Ben More. But the importance of the section requires 

 more detailed description. 



The gneiss (No. 73, p. 416) overlying the conglomerate is similar 

 to ordinary granitoid Hebridean; but associated with it are some chlo- 

 ritic bands. Ascending the slope above the northern bank of the cas- 

 cade, we find the prevailing dips of the gneiss are still at a low angle 

 to E.j^.E. Here and there, however, the foliation abruptly changes 

 to vertical with a northerly strike. Continuing along to the north- 

 east, round the cliffs on the north-west side of Dhuloch Beg, the 

 usual dip is about 20° to JN".E. ; but further east it gradually rises 

 to nearly 90°, with strike to the north. The precipices overhanging 

 the N.N.W., N., and N.E. sides of the loch are formed of the gneiss, 

 still almost or quite vertical, striking N. 10° E. Ascending Eagle 

 Rock (2345 feet), I found the gneiss, with a northerly strike, right 

 up to the summit. On the south-east slope lies a thin band of 

 quartzite, dip S.S.E. at 15° ; but at the extreme south-eastern 

 point of the mountain the gneiss reappears (No. 76, p. 415). 



Returning to the Oykel valley, and working from the gneiss 

 back to the conglomerate along a more southerly line, we observe 

 similar facts. Leaving behind us the igneous mass north of Loch 

 Ailsh, we reach our ground at about two thirds of a mile south of 

 Dhuloch Beg. Climbing the scarp to a height of about 1000 feet, 

 we first come to about 15 feet of quartzite, with, red felspar bits, 

 dipping south-easterly at 30°-40°, and underlain by a few beds of 

 sandstone and grit. Then, between this point and the Dhuloch 

 Beg cascade, half a mile to the north-north-west, we have the 

 following descending succession : — 



Massive gneiss, vertical, foliation-strike N.N.E.-N.E, probably on the 

 strike of the vertical gneiss on the loch. 



Do., underlain by soft mica-schist, dip E. at 60°. 



Do., dip N.E. at 70°. 



Do., dipE.lS.E., 60°-70°. 



Do., at junction with conglomerate in cascade, dip E.N.E., 40°. 



