ANiS'IYERSAliT ADDRESS OF THE PRESIDENT. 53 



Logan, through Ben Fyn and the district cast of it, and so 

 broadening out occupies the coast from Loch Ailsh to Arisaig. 

 Again it reappears, on the eastern side of a fault, near the head of 

 Loch Eil (on the northern shore of which is a small area of Torridon 

 Sandstone), extending to Port William on the Caledonian Canal. 

 The triangular space between these two districts was occupied, as 

 he showed, by a series of rocks corresponding lithologically with the 

 middle zone of the Hebrideans of the Loch-Maree region. To these 

 three lithological groups Dr. Hicks gave the names respectively of 

 the Loch-Maree, the Loch-Shiel, and the Gairloch or Ben-Fyn series, 

 and he inclined to hold them stratigraphically distinct one from 

 another. Dr. Hicks also admitted in this paper the gneissic charac- 

 ter of the so-called syenite of Glen Logan, and classed it with the 

 Loch-Maree group, stating that in the upper part of the glen he 

 had found that it abutted on rocks belonging to the Ben-Fj^n 

 group. 



The perplexing schists on the southern side of Glen Logan 

 (named by him the Glen-Docherty beds, which occupy a consider- 

 able area on either side of the latter glen) are separated from the 

 rest, and their age is left by him in uncertainty. It cannot be 

 denied that in this paper Dr. Hicks made to the controversy a contri- 

 bution of the highest value, and may claim to have brought Highland 

 reform into the region of practical politics. He had shown that 

 unless lithological similarity was to be utterly disregarded as a factor 

 in correlation in two areas almost neighbouring, a very large 

 portion of the western Highlands north of the Caledonian Canal was 

 occupied by rocks which were substantially identical with an im- 

 portant series of admittedly Hebridean age, and exhibited the 

 same lithological sequence. 



But this was by no means the only blow dealt in the course of the 

 year. Three months later was read a third communication from 

 Dr. Callaway, printed in the same volume, " On the Age of the newer 

 Gneissic Rocks of the Northern Highlands." This elaborate paper 

 was the result of work done chiefly during the summers of 1881 

 and 1882, in the districts around Lochs Broom, Assynt, and Erriboll. 



The following is a summary of Dr. Callaway's principal conclu- 

 sions : — 



(1) The " Upper Uuartzite " of some authors is, in these districts^ 

 simply a repetition by folding of the so-called Lower Quartzite ; the 

 " Upper Limestone " on Loch Ailsh is marble and crystalline dolo- 

 mite in the Eastern-Gneiss series (Upper Gneiss of Murchison) ; the 

 Assynt series (Palaeozoic) has been doubled back upon itself in a com- 

 pressed synclinal fold along Loch ErriboU, while along Loch Broom the 

 dolomite (of the Palaeozoic series) does not come into contact with the 

 Eastern Gneiss at all, but is separated from it by older faulted 

 rocks. 



(2) In the three areas described the Assynt series and the Eastern 

 Gneiss display a discordant strike and dip. 



(3) The " igneous rock " of some authors, that now commonly 



VOL. XLI. c/ 



