384 PROFESSOR GEIKIE ON THE 
shivery kind. They consist entirely of the surrounding metamorphic rocks, 
quartz-rock and flaggy gneiss being particularly abundant. The matrix has a 
red sandy character. 
On the mainland, conglomerate of a similar kind begins at Coalbackie, not 
far from the mouth of the Kyle of Tongue, and stretches southward in a con- 
spicuous ridge and detached craggy eminences as far as Ben Stomino, on the 
east side of Loch Laoghal. Its unconformable relation to the underlying 
crystalline rocks on the shore was clearly pointed out by CunnincHAM.* 
Another feature to be noticed at that locality is the remarkable unevenness of 
the platform on which the conglomerate was deposited. The accompanying 
diagram (fig. 3) will illustrate this structure. On the shore we find the upturned 

Fig. 3.—Sketch-Section of the relations of the Old Red Conglomerate to the underlying 
Quartz-Rock in the Kyle of Tongue. 
edges of the flaggy micaceous quartz-rock wrapped round with coarse red con- 
glomerate, and forming a small isolated stack within tide-marks. A large mass 
of the conglomerate runs inland for a few yards, and presents a vertical face on 
one side. Immediately beyond it the underlying quartz-rock reappears, while 
at the base of the long slope which rises up to Coalbackie the conglomerate 
again occurs. A small fault may form the upper limit of this patch. At the 
summit of the slope lies the huge conglomerate cliff of Cnoc Vreckan, 
the final north-westerly escarpment of the Old Red Sandstone on the 
mainland. 
From the steep truncated end of the ridge above Coalbackie, the con- 
glomerate (with sometimes a basement of red sandstone, seen particularly below 
the east slope of Cnoe Vreckan) runs southward for several miles, It forms 
the detached outlier of Cnoc Craggie, and rises high upon the sides of the 
granite mass of Ben Stomino. Its bottom there must be somewhere about 
* Op. cit. 

