EOCKS OE THE NOETHEEN HIGHLANDS. 



371 



" Logan Rock " of Glasven. — It is necessary here to anticipate a 

 part of our proposed discussion on this disputed rock. In the upper 

 part of Calda Burn the Quartzite rests upon gneiss. This rock is 

 massive and coarsely crystalline. Were there no theoretical reasons 

 to suggest a contrary conclusion, I think it would occur to no one 

 acquainted with the district that this was any thing but the ordinary 

 Hebridean, which appears in place a mile and a half to the west. 

 Many hand-specimens taken at random from both localities are quite 

 undistinguishable. With the exception of a thin capping of quartz- 

 ite, this gneiss forms the chief mass of Glasven (2541 feet). The 

 bedding is much contorted, but is, on the whole, towards the east. 

 According to the received view, this gneiss is conformably interca- 

 lated between the Dolomite and the " Upper " Quartzite. But in our 

 former section (fig. 2, p. 368), the quartzite is alleged to rest, and 

 does appear to rest, upon the dolomite. We are therefore asked to 

 believe that this great mass of gneiss has thinned out within 500 

 yards. Other difficulties will be pointed out further on. 



Section from the west end of Ben Uarran to the high road 

 south of Inchnadamff (fig. 4). 



This line runs parallel to Poulan-drein, at a distance of about 400 

 yards. Standing at the fall over the /SaZ^r^ZZa-quartzite in Poulan- 

 drein, and looking along the strike to the south-east, we can see the 

 Dolomite (upper section in fig. 3) rising up into the low ridge behind 

 the house called in the Ordnance Map Glenbain, and the beds can be 

 traced without a break between the two points, and on continuously 

 to the S.E., dipping steadily to the S.W., and forming the N.E. side 

 of the Stronchrubie syncline. At Glenbain the Dolomite is regularly 



Fig. 4. — Section betiveen the west end of Ben Uarran and the high road south of 

 Loch Lnchnadamff. (Scale 3 inches to 1 mile.) 



Ben 

 N.E. Uarran. 



Talus. 



Stronchrubie 

 syncline. 



W.S.W. 



underlain by the Brown Flags, just as on Poulan-drein, but with a 

 lower dip ; and to the south-east the Annelidian Quartzite comes in 

 conformably under the flags. Turning to the N.E., and ascending the 

 slopes of Ben Uarran, we pass outcrops of the same quartzite. Then 

 we find it rollover slightly to the N.E. and after a narrow interval 

 occupied by talus, we come again upon the Annelidian Quartzite almost 

 vertical. It is impossible to speak with certainty of what underlies 

 the talus ; but it may mask the prolongation of the Poulan-drein 



