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Proceedings of the Royal Society 
Mr Macpherson adds that there are no gneiss or granite rocks in 
the island ; that he has seen rocks of that description in islands 
and on the mainland, to the N.W., hi., and N.E., hut that being 
not sufficiently acquainted with the qualities of these rocks, he 
cannot venture to indicate the sources of the Eigg boulders."^ 
* Note by the Convener , — The foregoing report on Eigg having been submitted 
to Professor Heddle, he wrote to the Convener that he had never visited Eigg, 
but that he was well acquainted with the rocks in Bum, Mull, and Skye. He 
states that there is no true granite in Rum ; but that at the S.W. corner of 
the island there is a large mass of a “ variety of syenite, something like grey 
granite” ; and that this syenite, and also the augite rock of the island, are of 
the “ same type as that of the Coolins in Skye, and of St Kilda.” He adds 
that this augite rock is so peculiar, that if the Eigg boulders came from any 
of the above-mentioned rocks in these islands, he might perhaps be able to 
recognise them, on getting chips from the boulders. 
In consequence of this last remark by Professor Heddle, the Convener applied 
to Mr Macpherson, to endeavour to obtain chips of the larger boulders in Eigg. 
In the course of a few weeks about a dozen chips were obtained, and were sent 
to the Convener. 
The Convener thereupon forwarded them to Professor Heddle, who, after a 
first cursory exaraiuation, wrote to the Convener as follows: — “Hone of the 
boulders (judging by the chips) are from any point I know. Hone are granitic. 
One is a micaceous syenite, with characteristic radiation structure in its fel- 
spar. There is a micaceous gneiss — I think a Tiree rock. The others are either 
highly metamorphosed grits, simulating granites, or gneissose rocks. All are 
so characteristic that their source is certain to be sooner or later discovered. 
The island should be visited, to note carefully the features of the ‘ lie ’ of each 
boulder.” 
A few days afterwards Professor Heddle wrote to the Convener, that having 
again examined the chips he found that “they consist of highly meta- 
morphosed grits of gneiss, and of syenite ; — they are all of much greater age 
than any rocks described as occurring in Eigg”; and suggested that they 
might be submitted to Mr Archibald Geikie and also to Professor Judd, both 
of whom he knew were well acquainted with West Highland rocks. 
The Convener accordingly transmitted the chips to Professor Judd, with a 
request that if Mr Geikie was in London, he would have the goodness to show 
them to him. 
The Convener has received a note from Professor Judd stating that Mr 
Geikie and he had looked at the specimens, and he fixes on one which he says 
“I take for Torridon Sandstone, It is an Arkose, which Mr Geikie thinks 
may have come from the Torridon group ; — but that it reminds him most of 
some parts of the Old Red Sandstone. Hone of the boulders are at all like any 
of the volcanic masses of the Inner Hebrides.” 
“ All the boulders, we both agree, may have come from the great gneiss 
masses of the central Highlands, and they do not appear to belong to the old 
Lewisian or Laurentian series. Mr Geikie adds, ‘ I do not think anybody 
could venture to fix their source more precisely ’ ; and in this I quite agree 
with him 
Mr Geikie, in his account of the Geology of Eigg, adverts to the channe 
