168 Proceedings of the Royal Physical Society. 
fine-grained granite. It is indeed a sort of link between 
granite and porphyry. Some of the coarser grained arenaceo- 
argillaceous strata seen at this place also show a transition 
to a kind of syenitic granite, — a fine-grained mixture of 
quartz, felspar, and horneblende, with or without mica. The 
appearances at the junctions of the granite and greywacke 
of Cockburnlaw, in Berwickshire, are exactly similar to those 
so beautifully exhibited at this part of Glencoe. Further up 
the glen, highly metamorphic rocks occur, blending the 
characters of the porphyry and schistose rocks in endless 
variety. The strata and laminae are distinctly marked, ver- 
tical, with a N.N.E. strike. These consist of quartz, com- 
pact felspar, and micaceous hornblende, being technically 
gneiss. Many rocks in Glencoe which have been termed 
porphyries are evidently nothing more than highly meta- 
morphic schists, generally dark coloured, frequently retain- 
ing most unequivocally their original planes of stratification, 
and containing less or more felspar absorbed from the 
igneous masses which caused their metamorphism.. The 
whole glen, as well as the wild and rugged district between 
it and Ben Nevis, are of the highest geological interest, 
especially as bearing upon the subject of this paper and 
igneous metamorphism in general. Of the wondrous scenery 
of this part of Scotland it is unnecessary to speak. 
2. Ben Nevis. — At Nevis bridge, and across the level mouth 
of the glen to where the ascent begins, metamorphic schists, 
similar to those seen in Glencoe, dip S.S.E. 50° and upwards. 
Immediately on commencing the ascent on the west side, 
granite appears, the faces of the rock having a direction 
nearly N.N.E. to S.S.W. At the top of the first ascent 
(about 2500 feet or more), the granite is extensively ex- 
posed, massive and divided by fissures running E.N.E. to 
W.S.W., which look suspiciously like traces of planes of 
stratification. These are crossed by a few others ranging 
N. by E. to S. by W. This granite appears to be a com- 
pound formed by the fusion, or partial fusion, of the strati- 
fied rocks by the porphyry. The coincidence in the direc- 
tion of its principal divisional planes with the strike of the 
schists at the mouth of the glen, seems much in favour of 
