IN THE NORTH-WEST HIGHLANDS OF SCOTLAND. 383 



of fossiliferous Lower Silurian rocks under enormous masses of 

 gneisses and schists, and the proof thereby afforded of a vast regional 

 metamorphism which could not be other than of Silurian age. 

 He was entirely in error when he believed his younger gneiss 

 to be merely metamorphosed Lower Silurian strata ; but that the 

 crystalline rocks of the Eastern Highlands contain the records of a 

 gigantic Post-Lower-Silurian metamorphism is now established 

 beyond dispute on evidence of which he never dreamed *. 



The order of succession advocated by Murchison, and supported 

 by Professors Kamsay, Harkness, A. Geikie, and others, seemed to 

 furnish a simple solution of the geological phenomena of the High- 

 lands, and hence met with general acceptance. 



In 1878 the controversy was reopened by Dr. Hicks, in a paper 

 " On the Metamorphic and Overlying Rocks in the neighbourhood 

 of Loch Maree "t. While agreeing with Murchison that there is a 

 perfect passage from the quartzites, " Fucoid-beds," and limestones 

 into the overlying flaggy strata of Glen Logan and Glen Docherty, 

 resembling the Lower Silurian flags of Wales, he maintained that 

 the flaggy strata rest unconformably on the Pre-Cambrian Archsean 

 rocks of Ben Fyn. Subsequently Dr. Hicks disputed that the 

 eastern schists rest conformably on the Lower Silurian strata. He 

 arranged the Pre-Cambrian rocks in three groups — («) lower, con- 

 sisting of massive gneisses (Loch Maree) ; (6) middle, comprising 

 more banded gneisses (Loch Shiel) ; (c) upper, composed of crystalline 

 schists (Ben Eyn) ; and contended that, between Glen Shiel and the 

 Highland border, there are representatives of various Archaean rocks 

 with patches of Silurian strata resting on them unconformably. 



In 1880 an important contribution towards the solution of the 



* " On the Relations of the Crystalline Eocks of the North Highlands to the 

 Old Red Sandstone of that region, and on the recent Discoveries of Fossils in 

 the former by Mr. Charles Peach/' Brit. Assoc. Rep. 1855. 



"The Quartz-rocks, Crystalline Limestones, and Micaceous Schists of the 

 N.W. Highlands of Scotland proved to be of Lower Silurian age through 

 the recent fossil discoveries of Mr. C. W. Peach, with a Note on the Fossils 

 by J. W. Salter," Brit. Assoc. Rep. for 1857.: 



"On the Succession of the Older Rocks in the north-west counties of 

 Scotland, with some observations on the Orkney and Shetland Islands," Quart. 

 Journ. Geol. Soc. vol, xv. p. 353. 



" Some Results of Recent Researches among the Older Rocks of the High- 

 lands of Scotland," Brit. Assoc. Rep. for 1858, p. 94. 



" Supplemental Observations on the Order of the Ancient Rocks of the 

 North of Scotland and their associated Eruptive Rocks," Quart. Journ. Geol. 

 Soc. vol. xvi. p. 215. 



" On the Altered Rocks of the Western Islands of Scotland and the 

 North-western and Central Highlands." By R. I. Murchison and A. Geikie. 

 Quart. Journ. Geol. Soc. vol. xvii. p. 171. 



t Quart. Journ. Geol. Soc. vol. xxxiv. p. 811. 



On the Pre-Cambrian Rocks of West and Central Ross-shire," with Petro- 

 logical Notes by T. Davies. Geol. Mag. dec. 2, vol. vii. pp. 103, 155, 222, 

 266. 



•' On some Recent Researches among the Pre-Cambrian Rocks of the British 

 Isles," Proc. Geol. Assoc, vol. vii. p. 59. 



" On the Metamorphic and Overlying Rocks in parts of Ross- and Inverness- 

 shires," Quart. Journ. Geol. Soc. vol. xxxix. p. 141. 



Q. J. G. S. No. 175. 2 d 



