50 



NATURE 



[November 17, 1892 



limestones and quartzites of Durness and Loch Emboli, 

 in which Peach had recently discovered fossils. The 

 last group appeared to be conformibly overlaid by a 

 great mass of crystalline schists, waich came to be 

 known afterwards as the " Upper or Eastern Gneiss." 

 Though the fossil evidence was then incomplete, Mur- 

 chison saw nothing in it to forbid the belief thxt the 

 Durness beds were of Lower Silurian age, and his conjec- 

 ture was confirmed by the discovery of better specimens. 

 This conclusion was announced in a paper read before 

 the Geological Society in 1858, in which it was also stated 

 that the author looked upon the Upper Gneiss as meta- 

 morphosed Silurian. 



In the meantime Nicol had read a paper before the 

 Geological Society (1856), in which he describes the 

 joint explorations of himself and Murchison, and some 

 subsequent work of his own. He recognizes the same 

 main sub-divisions as Murchison, but still leans to the 

 old notion that the Torridon sandstone belongs to the 

 Old Red ; this involves the assigning a later date to the 

 Durness Beds, and these he thinks may be Carboniferous. 

 But he is content to hold this merely as a provisional 

 hypothesis till further fossil evidence is forthcoming. 

 With respect to the Upper Gneiss he is very cautious, 

 suggesting that it may be a newer metamorphic group, or 

 may be merely a portion of the lower, that is Hebridean, 

 %xv€\%% forced up by some great convulsion. This latter 

 solution was evidently present very vividly to his mind, 

 for it is repeated, as a possible explanation, no less than 

 three times. 



Here a very important difference of opinion between 

 Murchison and Nicol makes its appearance. 



It was probably about this time, but the map bears no 

 date, that Nicol issued a new geological map of Scot- 

 land. In this all gneiss is denoted by one colour ; but 

 the explanation states that the author does not consider 

 all the Scotch gneiss to be of the same age ; that the tract 

 of this rock, with associated quartzite and limestone, 

 stretching from Aberdeenshire through Perthshire to the 

 Breadalbane Highlands of Argyllshire, may be a newer 

 formation ; while he is disposed to look upon the great 

 mass of gneiss, extending from the north coast of Suther - 

 land southwards through Ross-shire and Inverness-shire, 

 rather as belonging to an older period. The Torridon 

 sandstone is distinguished by a separate colour, though 

 the author is still inclined to class it with the Old Red. 



Nicol expounded his views to the British Association 

 at Aberdeen in 1859, and again in a paper read before 

 the Geological Society in i860. He adduces many rea- 

 sons for doubting the existence of an "upward conform- 

 able succession " from the Durness Beds to the Upper 

 Gneiss, and explains the sections on the supposition that 

 this rock is the Hebridean Gneiss brought up by faults. 

 Though the expressions, " forced up by convulsion " and 

 "pushed up over," which he uses in his paper of 1856, 

 seem to show that the notion of what we call " Thrust 

 Planes" was present to his mind, the sections of this 

 paper hardly bear out that inference. He neatly twits 

 Murchison with failing to see that the principles which 

 he had applied with such success to an explanation of the 

 structure of the Alps were equally applicable to the 

 North-west Highlands. In 1861 Murchison stoutly main- 

 tained his view regarding the Upper Gneiss ; with an ad- 

 NO. 1203, VOL. 47] 



vocate's skill he hits Nicol hard on his weak point, justly 

 urging "that local interferences of eruptive rock nowise 

 set aside broad data." In the same year was issued the 

 " First Sketch of a new geological map of Scotland by Sir 

 R. I. Murchison and A. (now Sir A.) Geikie," in which 

 Murchison' s views vere adopted. 



Here then was a promise of a fair stand-up fight be- 

 tween two champions, each well able to hold his own. 

 But the promise was not fulfilled. The combat would 

 have been far from equal. On the one side there were 

 the pull which wealth and social position bring with 

 them ; the advantage which accrues from living in Lon- 

 don and having thus the ear of a great centre of scientific 

 life ; and that pushing ambition, that eagerness to secure 

 precedence in discovery, which so often go along with an 

 active and energetic disposition. On the other side there 

 were comparative social insignificance ; residence in a 

 hyperborean region far more difficult of access than now ; 

 a happy indifference to fame based on a confidence that 

 the settlement might be safely left to time, and that the 

 world would go on pretty much as heretofore, whichever 

 of the two turned out to be nearer the truth : more than 

 all a reluctance to embitter the closing years of life with 

 anything that looked like an altercation with an old and 

 esteemed friend and fellow-worker. So, because it takes 

 two to make a quarrel, the fight never came off. Natur- 

 ally, under these circumstances, (and can we blame it ?) 

 the world took the man who vigorously pushed his views, 

 at his word ; he had plenty to say in their favour and said 

 it well ; no one gainsaid him ; his contention was ac- 

 cepted. There will be those who, without presuming to 

 blame, do not covet success on such terms ; and whose 

 sympathies go out towards the peace-loving old man 

 who was content to bide his time and possess his soul in 

 silence. 



And so the " Upper Gneiss " and " the upward con- 

 formable succession " held their own ; and in the geologi- 

 cal map of Scotland, issued in 1876 by the present 

 Director-General of the Geological Survey, the crystal- 

 line schists of the Central Highlands are designated 

 " Metamorphosed Lower Silurian." It would be tedious to 

 enumerate all the points in which this map is an improve- 

 ment on the " First Sketch" of 1 861, but the student will 

 find it an instructive exercise to compare the two maps, 

 and ascertain by reference to memoirs on special dis- 

 tricts how each correction and addition was arrived at. 



The Highland problem remained in abeyance for nigh 

 a quarter of a century, though during that interval the 

 minds of many geologists were constantly recurring to it 

 and evidence was being accumulated to help towards its 

 solution. But it came to the front again, and like a giant 

 refreshed with sleep, when Prof. Lapworth in his " Secret 

 of the Highlands "(1883), and other workers in the same 

 ground, began to throw doubt on the explanation which 

 had so long held the field. When the Geological Survey 

 were able to take up the question and woik out the 

 ground with precision and detail that no observer could 

 attain to single handed, the anticipations of their im- 

 mediate predecessors were substantially confirmed, and 

 of the earlier observers it came out that Nicol was nearer 

 the truth than his illustrious antagonist. 



It calls for no small exercise of judgment, in an en- 

 deavour to depict the geology of so complex a district on 



