NATURE 



49 



THURSDAY, NOVEMBER 17, 1892. 



THE GEOLOGY OF SCOTLAND. 



Geological Map of Scotland. By Sir Archibald Geikie, 

 D.Sc, LL.D., F.R.S., Director-General of the Geolo- 

 gical Survey of Great Britain and Ireland. With de- 

 scriptive text. (Edinburgh: J. Bartholomew and Co., 

 1892.) 



THERE have been many attempts to frame a popular 

 definition of man. To call him a "story-loving 

 animal " would not be the worst of them. It may indeed 

 turn out, when we understand monkey-talk a little better 

 than now (and the hope that we may is, we are assured, 

 not unreasonable), then it may be that this will prove to 

 be not an exclusive definition. But this by the way ; the 

 description will hold for the present. Hence the delight 

 with which we listen to all that the various branches of 

 history, the history of the growth of knowledge included, 

 have to tell us. It is the stories which first attract us, and 

 they retain their charm long after we have learned that 

 the study of history has other ends to fulfil besides the 

 satisfaction of that craving for story-hearing which lies 

 deep in our being, and the gratification of a natural 

 curiosity to learn about things which we have not seen. 

 But the conviction ihat history should be to us something 

 more than a string of ancedotes soon forces itself upon us. 

 In tracing the growth of any branch of knowledge, in 

 noting the steps by which, one by one, each advance has 

 been made good, our interest lies first of all in the ac- 

 quaintance, almost of a personal character we may say, 

 which we make with the pioneers of a movement of which 

 we see not perhaps the full development but the ripening 

 fruit. We watch with absorbed attention their approach 

 to the unexplored land ; we follow them along the tracks 

 by which they first traversed it ; we stand by while 

 they note and record all that is novel and characteristic 

 in its features ; we mark the birth and growth of the con- 

 ceptions which their exploring work gives rise to ; we live 

 over again their fascinating life of discovery and deduc- 

 tion. But beside and beyond all this, their story, like 

 the stories of all history, carries with it a lesson ; and 

 their caution or rashness, as the case may be, in general- 

 izing and drawing conclusions, serves as example or warn- 

 ing to us. We look up to candour and a readiness to 

 court criticism and give up explanations which are shown 

 to be untenable ; anything like partizanship and a weakly 

 parental predilection for the children of one's own brain 

 we look down upon with sorrowing pity. 



The history of the steps by which a knowledge of the 

 geology of a country has been arrived at is written in the 

 successive versions of its geological maps. The appear- 

 ance of a map which embodies the results of the latest 

 researches into the geology of Scotland tempts us to look 

 back upon the earlier efforts to unravel the complications 

 of its geological structure. And this all the more because 

 we are dealing with a country in which Geology, as we 

 know it, may be said to have come to the birth ; and 

 because it is to Scotchmen that we owe the first showing 

 forth of these principles, whether of observation, de1uc- 

 tion, or inductive confirmation, which have been the guide 

 NO. I 203, VOL. 47] 



of geologists ever since. To Hutton, the precursor of 

 Lyell, to Hall, the scientific ancestor of Daubrde, and to 

 the line of illustrious followers who have carried on with 

 such brilliant success the work which they started. 



Among the earliest attempts to deal with the geolo- 

 gical mapping of Scotland are the mapsof Macculioch's 

 "Western Islands," which bear the date of 1819. It is 

 hard for us to realize how much of Scotland was at that time 

 without adequate topographical delineation. Our present 

 Ordnance Maps are far from being a credit to the Depart- 

 ment which issues them, and the language which attends 

 an attempt to use them on the mountainous moorlands, 

 though not a whit stronger than is justifiable under the 

 circumstances, had better be left to melt into thin air 

 around the spots where it was uttered. But our geological 

 life is one of luxury compared with Macculioch's, whose 

 atlas is one string of apologies for the inadequate maps 

 on which he had to record his observations. The map of 

 the Isle of Man "is obviously very inaccurate, but there 

 was only a choice between it and two others equally un- 

 worthy of confidence." The map of Staffa " was drawn 

 under every unfavourable circumstance, and cannot fail 

 to be inaccurate, having been merely paced with the 

 assistance of a pocket compass in a severe gale of wind 

 and rain." 



Macculloch seems to have projected, but never com- 

 pleted, a geological map of the whole of Scotland. The 

 materials collected by him were however utilized by the 

 Highland Society in the construction of a general map 

 in 1832. 



Passing by the maps of Boud, and a sketch of 

 Murchison's and Sedgwick's, laid before the Geological 

 Society in 1S28, we come to the publication of Nicol's 

 '* Guide to the Geology of Scotland " in 1844. 



In a cou:)try where the rocks are so largely unfossil- 

 iferous, it is natural, even necessary, that the earliest 

 geological maps should be more of a lithological than a 

 stratigraphic.il character, and this is the case with the 

 maps so far noticed. In the map which accompanies 

 Nicol's guide, and which he says is based on Maccul- 

 ioch's, some of the main varieties of the crystalline 

 schists are distinguished, but the order in which they 

 occur is not indicated. One colour comprises all the red 

 sandstones, the Torridon, the Old Red, and even the red 

 rocks of Dumfriesshire; under the head of "Porphyry 

 and Trap" are lumped together all the volcanic rocks, 

 including those of the western islands and of the central 

 valley ; only two of the groups which we now call forma- 

 tions are separated, the " Carboniferous" and the "Lias 

 and Oolite." But the great leading features in the phy- 

 sical geography of Scotland are sharply marked out, the 

 three regions into which it naturally falls are lucidly 

 delineated, and the work is crowded with local details 

 that betoken acquaintance with the work of others and 

 patient investigation of his own. 



At the meeting of the British Ass iation at Glasgow 

 in 1855 Murchison gave an account )f the result of the 

 joint work of Nicol and himself iu the north western 

 Highlands. The existence of three, great sub-divisions 

 had been clearly established ; what we now know as the 

 Hebridean or Lewisian Gneiss at the base, the Torridon 

 sandstone resting unconformably on it ; while above that, 

 and separated from it by another unconformity, came the 



