1903-4.] Mr J. G. Goodchild on Intrusive Rocks. 223 
be studied are all within easy distances of Bunessan, where the 
Dunara Castle calls twice weekly from Glasgow. There are 
large quarries at Camas Tuadh, Ardalanish, and other places near, 
and there are exceptionally fine coast sections at Carraig Mhor and 
Torr na Sealga, which can easily he examined from Bunessan. 
Even in passing hy steamer from Iona to Oban the broader features 
■can easily be made out with the aid of a good field-glass. 
On referring to the older literature of the subject I find that 
some of the statements here put forth regarding the granite margins 
had, to some extent, been anticipated by previous writers. Thus 
M £ Culloch gives a most interesting account of the relationship 
Between the granite of Cruachan and the schists around, which 
tallies in almost every respect with what I observed in the Ross of 
Mull (see Trans. Geol. Soc. Lond ., vol. iv., pp. 126 et seq.). 
■Jameson noticed the same features in connection with the granite 
■of Braemar ( Annals of Philosophy , vol. iv., p. 419). Mr Carne has 
recorded similar facts around the granite of Cornwall (Geol. Trans, 
of Carnival/, vol. i., p. 22). So did Dr Davy; also Dr Boase, 
De la Beche, and others. But as these observers were not well 
acquainted with modern petrographical methods, it may be as well 
4o add to their testimony the evidence lately put forth by one of 
■our ablest workers in that department of science, which is accord- 
ingly subjoined. 
Since my paper “On a Granite Junction in the Ross of Mull” 
was published, my colleague, Mr Kynaston, has mapped the area 
around the granite mass of Ben Cruachan, which is probably of 
the same age as the granite of the Ross of Mull, and, like that mass, 
it rises through the Highland Metamorphic Series. In the 
■Summary of Progress of the Geological Survey of the United 
Kingdom for 1900 an outline is given of Mr Kynaston’s conclu- 
sions. These are so pertinent to the subject at present under 
consideration that no apology is needed for quoting them nearly 
in full. The quotation, pp. 73-74, is as follows: 
££ Great difficulty was experienced in mapping out the boundary 
line between the granite and the schists owing to the complicated 
nature of the marginal area. Indeed, in some places the granite 
and the schistose rocks are so intermixed that no sharply-marked 
Boundary-line can be drawn between them. . . . The contact zone 
