52 PEOCEEDIIfGS OF THE GEOLOGICAL SOCIETY. 



the Pebidian of "Wales, and a group of rocks comparatiyely un- 

 altered, which he regards as Silurian. 



In the volume for 1881 a new combatant appears, and the debate 

 is transferred to another region. • Dr. C. Callaway, in a short paper 

 on " the Limestone of Durness and Assjnt," comes to a conclusion 

 which perhaps may be most simply expressed in his own words. 

 He had selected the localities " because they alone are alleged to 

 have yielded fossils from the limestone, and because Murchison 

 regarded them as of primary importance in the construction of his 

 argument. My researches," he says, " led me to the conclusion, 

 not only that the sections were broken and therefore untrustworthy, 

 but that the relations of the several rock groups were inconsistent 

 with the supposition that the limestone passed below any part of the 

 newer metamorphic series." In another short paper jDublished in 

 the volume for 1882 he asserts the conformity of the quartzite with 

 the Torridon Sandstone in the Loch Broom and Loch Assynt region, 

 and on that ground maintains that the latter has more claim to be 

 referred to the lower part of the Ordovician than to the Cambrian 

 series. In a paper entitled '' Eirst impressions of Assynt," published 

 in the 'Geological Magazine' for 1882, Mr. Hudleston insists strongly 

 on the evidence of folding and faulting on a vast scale, doubting the 

 existence of the " Upper Quartzite," and bringing forward numerous 

 reasons for believing that the equivalent in that district of the 

 " syenite " of Glen Logan was, " from top to bottom, the local repre- 

 sentative of the fundamental gneiss, or something that is first cousin 

 to it." 



In the volume for 1883, Dr. Hicks returned undaunted to the 

 attack, and, in the chivalrous spirit of one who fights for truth 

 rather than for victory, took his old antagonist into his confidence, 

 and obtained his aid in the examination of his collections. In this 

 paper, which deals with an extensive district on the western side of 

 Scotland, between parallels of latitude drawn roughly through Fort 

 William on the south and the lower end of Loch Maree on the 

 north, Dr. Hicks gives the results of two journeys undertaken 

 subsequently to the year 1878, and brings forward very strong 

 evidence in favour of the following conclusions :— that in the district 

 between Loch Maree, the Gairloch, and Loch Torridon, the admittedly 

 Palaeozoic beds (Torridon Sandstone, Quartzites, &c.) rest upon the 

 Hebridean series, which exhibits in ascending order three litho- 

 logical types ; the lowest or most massive being exposed on the east 

 shore of Loch Maree : the middle or more banded gneisses occupying 

 a considerable area on the west shore of the same loch, and a strip 

 between the head of the Gairloch and the lower part of Loch 

 Torridon ; and the upper or micaceous schist-like group occupying 

 a strip which, starting from Ben AUigin, runs northward to the 

 head of the Gairloch, separating the two areas of the last-named 

 group. That the whole of the series is included in the Hebridean 

 of Murchison has never been questioned. Dr. Hicks then points 

 out that a group of rocks lithologically corresponding with the last- 

 named of these passes by Loch Pannich and the head of Glen 



