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PROFESSOR HEDDLE ON THE MINERALOGY OF SCOTLAND. 471 
west. The same rock continues, with slightly increasing angles, up the channel of 
the Allt for half a mile, when we come upon the junction with the schistose 
beds ; these conformably underlie the red beds at this point. Following up the 
burn, the dip of the older beds rapidly increases to nearly the vertical, when, 
after having passed over a considerable thickness of denuded strata, there is a 
sudden anticline, with an equally high dip in the opposite direction. 
There is now evident alteration, a good deal of fracturing,—occasioning 
many falls in the burn, and the heather-covered holes into which Professor 
JAMESON tells us he had many falls. In the col between Arstival and Halival 
we come upon the augitic rock, lying in flat sheets upon the upturned and 
most irregular edges of the strata; the contact is immediate, but the surface of 
junction is usually a very rough one. Passing under the toppling cliffs of 
Haiskeval, we observe many varieties and gradations of the rock. When first 
seen, it was a rough-grained mixture of greenish-brown augite, and pale, 
greenish-white, glassy labradorite, in which the crystals, less than half an inch 
im size, were mutually assertive ;—the decomposition of the felspar leaving 
tuns of gravelly-brown sand. 
The masses, fallen from the cliffs of the central hill, show gradations in both 
directions,—both as regards augmentation or diminution of the relative propor- 
tion of either constituent, and also as regards augmentation or diminution in 
the size of the component crystals. 
A compound which, from an unusual brilliancy of lustre and brightness of 
| colour, “could scarcely be distinguished from greenstone,” iscommon. Aphanitic 
masses are equally so; and in the clean-cut face of the towering cliff, the bedded 
arrangement is markedly developed by the suddenness of the alternations. 
In the col (1750 feet) between Tralival and Scuir na Gillean a breccia is 
seen; the sharp-angled fragments consist solely of varieties of the augitic rock, 
—not a particle of either sandstone, or schist, or grit being visible ; the paste 
is a green-blue “‘claystone.” This doubtless is the first of the breccias noted 
by Maccuttocu. 
This breccia is sticking on to the sides of Tralival ; whether it passes into its 
mass cannot here be seen. The hill towers for 550 feet above,—a mass of little 
else than crystalline brown augite, presenting a surface of most repellant 
roughness. 
The bulk of Scuir na Gillean, which overlies the volcanic breccia, is com- 
posed of slabby felstone, of a slate-blue colour, and generally of a porphyritic 
structure,—the imbedded crystals being a white or pale-blue felspar. 
The breccia and overlying rock do not seem to rest conformably upon the 
augitic beds, but to dip to the south-east. Upon the opposite side of Glen 
Dibadale a patch of the same rock is adherent to the south slopes of an outlier 
of Haiskeval; and it seems to descend the southern slopes of the Scuir to a lower 
altitude than on the northern. Be this as it may, it is, on the southern slopes 
