﻿I860.] 



NICOL N.W. HIGHLANDS. 



89 



rated from the main ridge by a low marshy valley, indicating a line of 

 fault. This fault is also proved by the quartzite, with its characteristic 

 annelid-tubes (Pipe-rock), dipping first 78°, toE. 30° S., and then 70°, 

 toW. 10° N. On the main ridge the same quartzite forms a great 

 curved face of rock, dipping at 50°-65°, to W. 33° N., and higher 

 up 74°, to W. 25° N. The top of the ridge consists of a granitoid 

 igneous rock or granulite *, in part overlain by quartzite. This 

 mass or vein varies from a few yards to above a fourth of a mile in 

 width. Beyond it, on the east side of the ridge, mica- and talc-slates 

 occur in thin regular beds, and often identical in character with the 

 rocks of Far-out Head. The prevailing dip is 15° to 25°, to S. 30° E., 

 but varies considerably near the granulite, where the beds become 

 contorted and interlaced with igneous matter. In a deep valley to 

 the north, a more complete section of the interior of the hill is seen ; 

 the granulite widening out to half a mile or more, throwing off the 

 strata on each side, and involving large fragments of the mica-slate, 

 with the laminae turned in various directions. As these fragments 

 of mica-slate are found in the mass of the igneous rock where it 

 rises up below the quartzite, and, of necessity, have been derived 

 from a still deeper formation, they prove indisputably that the mica- 

 slate is the lower and older rock, and therefore cannot normally 

 overlie the quartzite. 



Further north, the igneous rock widens out greatly in Arnaboll 

 Hill, and has produced some remarkable changes on the strata. 

 Thus, on Camas Bay, in the continuation of the fault in the former 

 section, the quartzite dips at 53°, to S. 64° E., and apparently 

 below the igneous mass of the hill. But the openings of the 

 annelid-tubes, and the ripple-marks, which are regularly found on 

 the upper surface of the beds, are here on the lower faces, showing 

 that there has been a complete reversal of the strata. Still proceed- 



Fig. 4.— Section of Drium-an-tenigh, Loch Erriboll. 



W. Heilaru Inn. Loch Hope. E. 



C/ 



d. Limestone. c 2 . Fucoid-beds. c 1 . Quartzite. 



x. Granulite (termed "gneiss" by Mr. Cunningham). 



ing northwards we come to the remarkable section of Drium-an- 

 tenigh (fig. 4), described and figured by Mr. Cunningham as an 



* It is difficult to assign a name to this rock. In general it is a mixture of 

 compact felspar and quartz, often with an imperfect laminar texture. With 

 these, hornblende or talc or scales of bronzite become occasionally intermixed. 

 But in other places it passes into a distinct crystalline binary granite of orthp- 

 clase and quartz, or into felspar-porphyry or diorite, and where in contact with 

 limestone into a kind of serpentine. With all this diversity it exhibits a com- 

 munity of character, more easily recognized than described, along the whole fine 

 from Whiten Head to the Sound of Sleat. I have often used the term granulite, 

 as the most generally applicable. 



