ANNIVEESAKT ADDRESS OF THE PEE8IDENT. 35 



morphic rocks of the Highlands, which he had as early as 1844 

 been the first to suggest were probably of the same geological age as 

 those of the Southern Uplands. In 1855, in his paper " On the Sec- 

 tions of Metamorphic and Devonian Eocks of the Eastern Extremity 

 of the Grampians " (Quart. Journ. vol. xi. p. 544), he proved the 

 existence of a grand fault between the metamorphic rocks and the 

 Old Red Sandstone of Kincardine and Eorfar. The same year he 

 visited the well-known Torridon and Durness area in the north-west 

 Highlands in company with Sir R. Murchison, in order to verify 

 Mr. Peach's discovery of fossils in the metamorphic limestone of 

 that region. On his return he communicated an independent 

 memoir to the Geological Society (Quart. Journ. vol. xiii. p. 17), 

 in which he claims to have published for the first time what is 

 now the generally accepted order of succession, viz. : — (a) Lower 

 Gneiss ; (5) Conglomerate and Eed Sandstone ; (c) Quartzite ; (d) 

 Limestone, overlain by (e) an Upper Gneiss. Arguing mainly 

 from the petrographical character of these rocks, he threw out 

 the suggestion that the Torridon Sandstone might be of Devo- 

 nian age, and that the overlying limestone and gneiss might be 

 of the age of the Lower Carboniferous. After Mr. Salter's demon- 

 stration that the fossils of the Durness Limestone were not Carboni- 

 ferous, but belonging to the deepest zone of Murchison's Silurian, 

 Nicol again visited the north-west Highlands. In a memoir giving 

 the chief results of this expedition (Quart. Journ. Geol. Soc. xvii. 

 p. 85) he retracted his former admission of an Upper Gneiss, 

 superior to the Durness Limestone ; and claimed to have proved that 

 the line of demarcation between the Durness series and the eastern 

 gneiss of Central Sutherlandshire is actually a line of fault, the Tor- 

 ridon and Durness strata always overlying or abutting against, but 

 never dipping under, the eastern gneiss. These new opinions led to 

 a keen controversy between himself and his old friend Sir E. Mur- 

 chison ; but after the publication of two additional memoirs on the 

 subject in 1862 and 1863, in which he defended his view that the 

 central gneiss of the Highlands is of the same general geological age 

 as the Lewisian gneiss of the Outer Hebrides, and that the only 

 metamorphic strata that can safely be called Silurian are the less- 

 altered rocks upon the outer borders of the Highlands, he ceased to 

 contribute papers to our Society upon the subject. A little work on 

 the Geology and Scenery of the North of Scotland contains his last 

 published words upon the controversy. He never ceased to wander, 

 however, year after year, among these Highland rocks in search of 

 fresh evidence in support of his view. Though he never published 

 the results of these later investigations, he remained fully convinced 

 of the correctness of his own view upon this question till the day of 

 his death. His opinions upon the Highland succession were shared 

 by a very few geologists in his day ; but there is every probability 

 that the whole question wiU soon be reopened by those who believe 

 that an opinion held so long and so tenaciously by such a modest and 

 patient investigator as Nicol is certain to have been founded upon 

 solid grounds. 



