﻿1861.] 



MTJKCHISON AND GEIKIE HIGHLANDS. 



197 



also observed. The map of this region would therefore represent a 

 series of irregular strips and patches of Silurian quartz-rock, inserted 

 among Cambrian sandstones by the agency of longitudinal faults 

 which seem to split off from or coalesce with each other. 



Towards the lower end of the valley the quartz-rock dips E. 10° 

 S., at 35°, and is followed by a band of limestone conspicuous from 

 the neighbouring hill-tops, owing to the bright verdure that marks 

 its course., Above the limestone come beds of quartz-rock and 

 quartzose flagstone ; and these, becoming more and more schistose, 

 cross Loch Coulan, and are seen in the ravines and watercourses on 

 the opposite side. They form, of course, the upper quartzose series 

 so frequently referred to. 



The region lying between the Grey Heads and Loch Doule has 

 never been explored. "We were able to see its general structure from 

 some of the neighbouring hill-tops ; but it must contain much in- 

 teresting detail to reward the fatigues of an enterprising geologist. 



Loch Carron. — After traversing this faulted district, the quartz- 

 rock approaches Loch Doule, whence it bends towards the south- 

 west, occupying the high ground on the north-west bank of Loch 

 Carron. At the head of the latter loch it is overlain by a limestone, 

 which extends for some way towards Jeantown, until lost beneath the 

 alluvial accumulations of the valley. 



The road from Jeantown to Applecross crosses a high ridge, and 

 descends to Loch Keeshom, through a ravine in which there is a well- 

 exposed section of the strata. First, on leaving Jeantown, we have 

 schistose beds with a south-easterly dip ; these gradually pass down 

 into a quartzose and flaggy series, which towards the lower end of tie 

 ravine are underlain by the quartzite. The next rock in descending 

 order is a limestone of great thickness, which occupies the south- 

 eastern side of Loch Keeshorn*. It dies rapidly away to north, and 

 a short way beyond the head of the loch has disappeared altogether. 

 It is underlain by white quartz-rock, which, coalescing with that 

 above the limestone, forms one series, below which lie the Cambrian 

 sandstones swelling up into the great mountains of Applecross and 

 Loch Duich. 



We had not time fully to work out the relations of the Keeshorn 

 limestone: possibly it may be the same as that of Loch Carron, 

 Loch Coulan, and Glen Cruchalie — that is, the limestone zone between 

 the lower quartz-rock and the upper quartzose flaggy series ; or, like 

 the lower limestone of Ben Eay, already referred to, it may be a local 

 deposit occurring in the lower quartz-rock. The area which will 

 decide this point is the high ridge on the northern side of the Loch 

 Carron Valley, between Lochs Keeshorn and Doule. 



The sections along the shores of Loch Carron at Strome Ferry are 

 singularly clear. They show the quartzose flagstones in well-defined 

 beds, dipping sharply to the south-east at 45° or more. The same 

 rocks occupy the intervening tract of land to the Kyles at Balma- 

 carra, where another admirable line of section can be examined along 

 the shore. 



* See Nieol, Quart. Journ. Gr. S. vol. xiii. p. 29: Murchison, ib. vol. xv. p. 188. 

 VOL. XVII. PAET I. P 



