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PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



[Feb. 6, 



here and there an emergence of the quartz-rocks and limestones, 

 and that the granites, syenites, porphyries, and other igneous rocks, 

 which occupy so large a portion of the chain, are necessarily of 

 comparatively young age. "We have indeed completely satisfied 

 ourselves, by ascending to the heights of Braemar on the one side, 

 and by entering into the heart of the chain from Aberdeen to Bal- 

 moral on the other, that whilst there are no clear proofs of the 

 existence of any altered rocks of even the lowest Silurian age, there 

 are certainly not in these mountains any strata of the Cambrian date, 

 and still less any traces of the fundamental gneiss of the North- 

 western Highlands and Islands. 



The old notion, therefore, that the Grampians contain the nucleus 

 of the most ancient rocks in Scotland, must now be abandoned. 



Appendix. By Sir Roderick I. Murchison. — February 6, 1861. 

 A memoir by Professor Nicol having been read before the Geo- 

 logical Society on the 19th December last, in which the author 

 exhibited several sections illustrating the relations and succession 

 of the stratified crystalline rocks of Sutherland, which were 

 directly at variance with the sections of the same localities which 

 had been published by myself (and confirmed by the observations 

 of Professors Banisay and Harkness), I then explained, viva voce, 

 how I conceived that Professor !Nicol had been misled by assigning 

 much too great an importance to what I considered to be local 

 and partial disturbances only. I argued that local interferences 

 of eruptive rock in nowise set aside the broad data I had for several 

 years been accumulating, which prove the existence of a funda- 

 mental gneiss, as distinguished by infrajiosition, direction of the 

 strata, and mineral characters from all the crystalline schists which 

 overlie those quartz-rocks and limestones that rest upon such older 

 gneiss. Professor Nicol, on the contrary, adhering to the views of 

 the older Scottish geologists (as represented in former maps of Scot- 

 land, and his own), considers vast masses of the rocks which I 

 ranked as overlying, to be simply the older gneiss brought up to the 

 surface, and placed in apparently overlying positions by enormous 

 upcast-faults. As his memoir has been published in the Journal of 

 the Geological Society*, I am bound to place on record that I hold 

 distinctly to the general accuracy of those sections which I published ; 

 and, believing that the alterations in them proposed by Professor 

 Nicol are either erroneous or founded on deceptive local appearances, 

 I consider that all his reasoning as founded thereon must fall to the 

 ground. 



I will here advert to those sections of Professor Nicol which are 

 most important. 



First, let us examine the section from Loch Eriboll (p. 92, fig. 5), 

 which passes across the ridge to the east of Eriboll House ; since this 

 is the very traverse made by Professors Banisay and Harkness, as 

 well as by myself. In that diagram the author exhibits much which 



* February 1801, vol. xvii. No. 65, p. 85, &c. 



