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 Oona (above 

 G-lencoe village), mica slate, approaching in character to 

 hornblende schist, dips W.S.W. about 70°. Above this, 

 mica slate interstratifled with 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 



