of the Scottish Highlands. 169 



and stratigraphical features. He noticed in all his sections the 

 occurrence in regular order of clay-slates, grits, greywackes, and 

 mica-schists. He also noticed the reversal of dip from south-east to 

 north-west as he proceeded from west to east across the Grampian 

 range. His final conclusion, however, as to the south-east heing 

 the normal dip, and the clay-slates consequently being the highest 

 members of the series, while the north-westerly dip and consequent 

 infraposition of the slates was owing to a reversal of the normal 

 order, seems now to have been incorrect, and was probably owing 

 to his strong Wernerian leanings. After the publication of these 

 papers little or nothing seems to have been done in the investigation 

 of these rocks. The great name of Murchison and the assent of 

 such men as Harkness, Ramsay, and Geikie swayed the scientific 

 world, and Nicol and his papers, both on the North-west and 

 Southern Highlands, were soon forgotten. However, time and the 

 unchanging mountains, in whose hands this great geologist had to 

 leave his cause, eventually proved the truth of his observations and 

 deductions. Afterwards the work of Dr. Callaway and Prof. 

 Lapworth in the north-west re-awakened interest in the problem, 

 the results being the final establishment of the essential principles 

 arrived at and maintained by Prof. Nicol. 



In a brief summary of the rocks of Highland Perthshire, 1 by 

 Mr. H. Coates, F.R.S.E., and myself, published in 1891, we gave 

 a table of the succession of the Highland rocks, which, though not 

 so much in detail, was practically the same as that given at the 

 end of this paper, and similar to the succession afterwards given 

 by Sir A. Geikie as the work of the Geological Survey in his 

 Presidential Address to the Geological Society, the great argillaceous, 

 arenaceous, and limestone zones being then marked out as follows, 

 in a descending order : — 



6. Quartzites, grits, greywackes, and other arenaceous rocks. 



5. Mica-schists, quartz-schists. 



4. Calcareous mica-schist and pure limestone. 



3. Mica-schist and quartz-schist in varying proportions. 



2. Quartzite, grit, greywacke, and conglomerate. 



1. Clay-slates, phyllites, and other argillaceous rocks. 



In the explanatory note accompanying his geological map of 

 Scotlaud, 3 published 1892, Sir A. Geikie gives a brief summary 

 of these rocks, using the term Dalraidian to define them, as he 

 had previously proposed in his Presidential Address. 3 He again 

 refers to the occurrence of annelid tubes in the quartzites, but does 

 not give their localities or horizons, and whether they are identical 

 with those described by the Duke of Argyll 4 and the author 5 in 

 1889 I am unable to say. 



1 Transactions Perthshire Society of Natural Science, vol. i, p. 221. 



2 Explanatory Notes to Geological Map of Scotland, p. 8. 



3 Presidential Address, Quart. Journ. Geol. Soc., vol. xlvii, 1891. 



4 "Bodies of Organic Origin": Hoy. Soc. of Edinburgh, 1888-9, p. 40. 



5 Trans. Perthshire Soc. of Nat. Science, vol. i, p. 116. 



