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Pre-Cambrian Rocks of Ross-shire. 161 
On reaching Glen Laggan at a high level, on the west side, another 
exposure of a somewhat similar rock is found. Much of this, 
however, puts on the aspect of a serpentinous schist, but the main 
mass still has a highly granitic appearance. It reaches up toa height 
of several hundred feet above the level of the river at this point, and 
may also be traced continuously for several miles in the face of the 
hill along this side, striking apparently in a N.E. direction. It 
_ afterwards descends into the low ground, towards: the upper end of 
the Glen. I walked along the ridge for several miles, and noticed 
its connexion with the associated rocks carefully. Where it is 
first met with, it looks as if it had been sharply cut across 
by a fault, and there is an indentation in the ground such as 
would lead one to suspect such an occurrence. It seems here to 
underlie the Limestone Series, and to be backed by the quartzites 
and the flaggy fucoidal beds. Whether this portion at the higher 
level is intimately connected with the mass described in Note 10, 
and with another which runs up at a low level in Glen Laggan, and 
exposed in the river at the entrance, cannot be accurately determined; 
but I believe all evidence points to this, and I have so indicated 
the connexion in the sections (in the present asin my former paper). 
The microscopical examinations, determined by Mr. Davies, from a 
series collected at all points, tend to the same conclusions. These 
results are described in Notes 11 and 12. 
[Nore 11.—A large grained crystalline association of quartz and 
red orthoclase, the relations of which are much like those of a 
granite, notwithstanding the apparent parallelism of the quartz 
groups. It is permeated by innumerable thin veins of a serpentinous 
substance, which varies much in translucency, and only occasionally 
shows traces of a crystalline condition. The rock weathers to a 
soft earthy substance resembling a kaolin, to some depth.—T-.D. ] 
[Nore 12.-—Resembles a coarse-grained felspathic granite. The 
microscope shows a large grained crystalline association of quartz 
and a reddish orthoclase, with some microcline. The quartz is in 
more or less continuous bands, but appears to be frequently broken 
up and disturbed locally. The orthoclase is cloudy through decom- 
position. Much limonite as pseudmorphs after small crystals of 
iron pyrites is distributed. 
A. Another specimen of the same rock mass shows more decided 
granitic characters. The felspar and quartz are more even in size, 
and the latter is not so marked in its parallelism. A soft greenish 
micaceous mineral is evenly distributed through it, and altogether 
this rock is macroscopically much like a granite. 
B. Another variety of this rock is very coarsely crystalline, some 
of the felspar being very distinctly crystallized rather than crystalline. 
The quartz is bluish and somewhat milky, and resembles the variety 
known as fatty quartz. The mica here too, though apparently 
chloritic, shares in the increase in the size of the constituents, and 
though sparse is generally distributed. 
C. Resembles A. in the relative size of the constituents, but 
contains much plagioclase. Nests of the green chloritic mica con- 
DECADE II.—VOL. VII.—NO. IV. ll 
