VICINITT OF THE UPPER PART OF LOCH MAREE. 107 



this most interesting question of the nature of mineral change in 

 metamorphic rocks, and the traces which they may have preserved 

 of their original structure. 



From the above observations it results that I am unable to recog- 

 nize any marked similarity between the Hebridean series about the 

 upper part of Loch Maree and the beds which are seen on Ben Fyn 

 and in the upper part of Glen Docherty ; while both microscopic and 

 stratigraphic evidence, as I read them, point to the identity of the 

 latter with the beds exposed in the northern escarpment of the 

 newer series. In this series the effect of metamorphism varies in 

 degree, as we have already shown, and increases in amount as we 

 advance towards the Central Highlands ; but the peculiar flaggy 

 character of the strata (long since pointed out by the late Sir E,. 

 Murchison) is retained ; and there is no resemblance, in any important 

 point, to the older series. It appears, then, to me that, so far as the 

 neighbourhood of Loch Maree is concerned, the views advocated by 

 that distiuguished geologist and his fellow-labourer Prof. Geikie are 

 fuUy confirmed by microscopic evidence. 



Discussion. 



Dr. Hiczs stated that he had studied the district under the most 

 favourable conditions of weather, and had measured the section 

 foot by foot. The rock regarded by Prof. Bonney as gneiss was 

 so regarded at first by MaccuUoch and Hay Cunningham; but 

 they saw ground for changing that opinion, and believing that it 

 was intrusive, in which they were confirmed by Mcol, Murchison, 

 and Geikie. It also cuts across the beds of the older gneiss, as 

 shown even in Prof. Bonney's diagram and map. He maintained 

 that the reading of the section in Glen Laggan which he had 

 already given is the true one. He objected to the diagrammatic 

 nature of Prof. Bonney's sections. He insisted on the exact agree- 

 ment between the rocks of Ben Fyn and those of Gairloch, and 

 their distinctness from the micaceous flagstones of the younger 

 series. He pointed out that the strikes of the several rocks do 

 not bear out Prof. Bonney's views. The iN'.W. strike of the lower 

 rocks in Glen Docherty is most marked; and this, with the high dip 

 and difi'erence in the characters of the rocks, proved conclusively to 

 his mind that the micaceous flags of the upper series, with a N.E. 

 strike and low dip, rest here on a floor of the old or western gneiss. 

 Mr. HuDLESTON had examined the district with the advantage 

 of Dr. Hicks' s sections and descriptions. He came to a conclusion 

 opposed to that of Dr. Hicks and agreeing with that of Prof. Bonney. 

 He was entirely opposed to Dr. Hicks's views concerning the section 

 in Glen Docherty. He demurred to the importance which Dr. 

 Hicks attached to the differences of strike among the gneisses. He 

 regarded the section at Loch Maree as by no means suitable to serve 

 as a typical one. 



