620 REPORT— 1901. 



occurring in the displaced masses, as igneous rocks intruded during the earth- 

 movements, and that he failed to realise the evidence bearing on dynamic meta- 

 morphism resulting from these movements. But I do not doubt that the verdict 

 of the impartial historian will be that Nicol displayed the qualities of a great 

 atratigraphist in grappling with the tectonics of one of the most complicated 

 mountain chains in Europe. 



The period now under review embraces the reopening of that controversy in 

 ]878 by Dr. Hicks, and its close in 1884 after the publication of the 'Report on 

 the Geology of the North-west of Sutherland,' by the Geological Survey.' The 

 Survey work has confirmed Professor Bonney's identification of the Lewisian 

 gneiss and Torridoii Sandstone in Glen Logan, Kinlochewe,'- brought into that 

 position by a reversed fault; and Dr. Callaway's conclusions regarding overthrust 

 faulting at Loch Broom, in Assynt and in Glencoul.' Special reference must be 

 made to the remarkable series of papers by Professor Lapworth on 'The Secret 

 of the Highlands,' in which he demonstrated the accuracy of Nicol's main con- 

 clusions, .and pointed out that the stratigraphical phenomena are but the counter- 

 part of those in the Alps, as described by Ileim.'* His researches, moreover, led 

 him to a departure from Professor Nicol's views regarding the age, composition, 

 and mode of formation of the Eastern Schists, for in the paper which he com- 

 municated to the Geologi.sts' Association in 1884 he announced that their present 

 foliated and mineralogical characters had been developed by the crust-movements 

 which operated in that region since the time of the Durness quartzites and lime- 

 stones.'' Allusion must be made also to his great paper 'On the Discovery of 

 the Olenellns Fauna in the Lower Cambrian Kocks of Britain,' in which he not 

 only chronicled the finding of this fauna at the top of the basal quartzite in 

 Shropshire, but suggested tlie correlation of the Durness quartzites and limestones 

 with the Cambrian rocks elsewhere.'' That suggestion was strikingly confirmed 

 within three years afterwards by the discovery of the Olenellus fauna in Ross- 

 shire. 



The detailed mapping of the belt of Cambrian strata has proved the striking 

 uniformity of the rock sequence. There is little variation in the lithological 

 ch.iracters or thicknesses of the various zones. Basal quartzites, pipe-rock, Fucoid- 

 beds, Serpulite {Salterclla) grit, limestone, and dolomite form the invariable 

 sequence, for a distance of a hundred miles, to the west of the line of earth-move- 

 ments. This feature is also characteristic of the fossiliferous zones, for the sub- 

 zones of the pipe-rock, the Olejiellus fauna in the Fucoid-beds, and the Salterella 

 limestone have been traced from Eriboll to Skye. Owing to the interruption of 

 the sequence by reversed faults or thrusts, the higher fossiliferous limestone zones 

 are never met with between Eriboll and Kishorn, but they occur in Skye, where 

 they were first detected by Sir A. Geikie." 



Regarding the pala?ontological divisions of the system, my colleague, Mr. 

 Peach, concludes ' that the presence of three species of Okmellus in the Fucoid- 

 beds and Serpu lite-grit of the North-west Highlands, nearly allied to the American 

 form OUneUus Tkom.?o?ii — the type species of the genus— together with Hyolithes, 

 Salterella, and other organisms found with it, prove that these beds represent the 

 Georgian tei-rane of America, which, as shown by Walcott, underlies the Para- 

 do.vides zone.' Hence he infers that there can be no doubt of the Lower Cambrian 

 age of the beds yielding the Olenellus fauna in the North-west Highlands. Mr. 

 Peach further confirms Salter's opinion as to the American facies of the fossils 

 obtained from the higher fossiliferous zones of the Durness dolomite and limestone. 

 He states that ' the latter fauna is so similar to, if not identical with, that occurring 

 in Newfoundland, Mingan Islands, and Point Levis, beneath strata yielding the 



' JVature, vol. xxxi. p. 29, Xovember 1884. 



- Quart. Journ. Geol. Soc, vol. sxxvi. p. 03. " Hid., vol. xxxix. p. 416. 



' Geol. Mafi., Dec. 2, vol. x. pp. 120, 193, 337. 



' Proc. Geol. Assoc, vol. viii. p. 438 : Geol. Mag., Dec. 3, vol. ii. 1885, p. 97. 



= Geol. Mag., Dec. 3, vol. v. pp. 484-487. 



' Quart. Journ. Geol. Soc, vol. xliv. p. 62. 



