188 



PKOCEEDLNTGS OF THE GEOLOGICAL SOCIETY. 



division -planes, which dip at 60° to S. 43° W. These rocks generally 

 weather to a dark rusty brown, probably from containing the prot- 

 oxide of iron. Soon after, the same rocks dip at 60° to N. 27° W., 

 again on the foliation of the slate, but in a few yards fall to 35°, N. 

 27° W., from a curve in the beds. The next acclivity is a fine- 

 grained mica-slate with a veined aspect, from the folia being arranged 

 in curved layers. The dip here is still low (30° to N". 17° W.), but 

 soon rises to 65°, N. 12° W., in a grey mica-slate full of quartz-veins. 

 This rock continues to the summit of the hill, where the dip is 55° 

 N. 17° W., and a nearly similar dip appears in the rugged precipice 

 along the ridge to the north. Other division-planes, dipping 70°, S. 

 50° W., are seen in these cliffs ; and a series of ridges and hollows, 

 like the outcrop of beds, run N. 50° W. across the top of the hill. 

 The rock there is still a light-grey mica-slate, with small garnets 

 rarely disseminated through it. 



s. 



Fig. 5. — Section of Ben Lecli. 



* e 



a. Red Conglomerate. 



b. Clay-slate. 



; \ \c 



c. Mica-slate. 



d. Greenstone. 



e. Felspar-porphyry. 



On descending the mountain on the north-east towards the top of 

 the great corrie that opens up from Loch Lubnaig, the mica-slate 

 passes into a coarse granular rock, full of rounded grains of quartz, 

 and almost like a greywacke, but still distinctly foliated. This is 

 again one of those transition-forms that so clearly illustrate the me- 

 tamorphic character of these rocks. The dip of these beds is 45° to 

 N. 18° E. ; but other planes dip at 67° to S. 38° W., and thus ap- 

 proximately parallel to the second set of division-planes already men- 

 tioned. It is, however, curious that these coarse-grained greywaeke- 

 like beds, both here and in other places, do not coincide in dip with 

 the slates or finer beds near them. Still lower on the mountain, 

 towards the south, mica-slate again appears, dipping 70° to N. 40° E. 

 Below it there is an irregular vein or mass of light-grey greenstone 

 decomposing in globular concretions, and probably the continuation of 

 the vein near Ardchullarie on the other side of Loch Lubnaig. Still 

 lower, a veryquartzose mica-slate,in thin beds, dips at 70° to N.27°W. 

 The stream continues to flow over irregular beds of mica-slate, in some 

 places much bent and contorted, and dipping E. at 10° to 30°, in other 

 places more regularly at 65° to N. 10° W. Near the foot of the 

 corrie the stream forms a series of picturesque linns over the ledges 

 of the fine-grained mica-slates, which dip at 70°-80° to N. 30°-40° W. 

 At the foot of the hill the dip falls to 60°, and further south to 



