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NICOL SOUTHERN GEAMPIANS.
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side of the glen consists of gneiss dipping 50° or 70° to S. 40°-50° E.
Further up, the red granite, still full of veins of porphyry, crosses
the stream, and is well exposed at a small fall in the river. Still
higher the valley contracts, and gneiss forms the lower portion on
both sides ; the beds much contorted, but dipping on the whole about
70° to S. 42° E.
Fig. 10. — Porphyry Vein in Granite, Ben Nevis.
(Length about 30 feet.)
The lower portion of Glen Nevis thus consists essentially of gneiss,
dipping, more regularly than might have been expected in the
vicinity of such a mass of granite, to the S.E. The mountains on
that (the south-east) side of the glen appear generally to be capped
by quartzite, which ought thus to overlie the gneiss. A great part
of this region, however, is now a mere desolate deer-forest, without
house or path, so that even in the finest seasons — and these too
rarely occur for the geologist — it is difficult of examination. In one
of the ravines on the south side of the Glen the following section
was observed (fig. 11).
Fig. 11.-
-Section of the South side of Glen Nevis.
N.
a. Quartzite.
b. Gneiss.
c. Red Granite
d. Mica-slate and Gneiss.
e. Red Granite.
The bottom of the valley is red granite — a branch of that in Ben
Nevis. It is covered by a fine-grained gneiss or hornstone, probably
altered by the igneous rock, which dips at 60° to S. 27° E., and above
passes into chloritous mica-slates, some dark, others light grey, and
also dipping at 65° to S. 27° E. These slates are in turn covered
by a bed of red granite, perhaps from 100 to 150 yards wide, which
runs along the face of the southern hills, and in another ravine is