166 Proceedings of the Royal Physical Society. 
to be most typically developed in association with the oldest 
sedimentary rocks. 
The following are a few notes (nearly as taken upon the 
spot) of the appearance presented at some junctions of gra- 
nite with stratified rocks. The localities being, in general, 
of easy access, it is hoped that in the course of the ensuing 
summer, many Members of the Eoyal Physical Society may 
be induced to visit one or more of them, especially as they all 
have the additional recommendation of grand or beautiful 
scenery. 
Localities referred to. 
1. Glencoe. — Beyond the bridge across the Cona (above 
Glencoe village), mica slate, approaching in character to 
hornblende schist, dips W.S.W. about 70°. Above this, 
mica slate interstratified wdth quartz rock continues for 
some distance up the glen. About a mile up, and not far 
below the place where the glen takes an easterly turn, a 
mass of extremely hard and tenacious porphyry appears 
among the schists. Its cleavage planes are stratiform, and 
dip E.S.E. about 50°. This appears to be a root vein from 
the mass in the interior of the mountain on the left. A 
little further up (almost at the bend), strata of quartose mica 
slate dip W. by N. about 50°, The high mountain on the 
left is formed of schists and quartz rock, highly metamor- 
phic, and heaved up and invaded by the porphyry. A fine 
junction of the latter with the schists is seen near this 
place (a little below Clachich), and may be traced for a con- 
siderable distance. The line of junction is uneven, but 
ranges nearly N.N.E to S.S.W. The metamorphism of the 
schists here is extreme. They resemble hornblende schists, 
or rather the highly altered dark-coloured silurian strata of 
some parts of the Lammermuirs, e.g.^ Cockburnlaw, &c. 
Some very distinct vertical rectangular cleavages are here 
seen in the porphyry, ranging N.N.W. by E.N.E. The rock 
which exhibits this structure is stratiform, the beds being 
three or four feet thick, and dipping about N.E. by N. 30° 
to 40°. On the upper side of this porphyry, the schists again 
appear, dipping W.N.W. 50° to 60°, much altered. At 
