128 Revieics — Prof. Geilde's Geological Map of Scotland. 



III. — Geological Map of Scotland. By Akchibald Geikie, LL.D., 

 F.R.S., Director of the Geological Survey of Scotland, Murchison 

 Professor of Geology in the University of Edinburgh. (W. and 

 A. K. Johnston and Co. : Edinburgh, 1876.) 



OF late years the work performed by the Official Geological 

 Surveys has made an immense addition to our knowledge of 

 the characters and inter-relationships of the rock-formations of 

 Britain. This addition, however, has been almost wholly confined 

 to two departments of Geological Science. While Stratigraphical 

 and Mineralogical Geology have advanced with gigantic strides, 

 Stratigraphical Palaeontology has remained almost at a standstill. 

 Originally occupying the proud position of friend and mentor to 

 Zoology and Geology alike, extending a helping hand to either. 

 Palaeontology now-a-days seems to bestow all her favours upon the 

 former. The philosophical zoologist has gradually been forced to 

 recognize the inestimable value of her counsel, and to expect from 

 her alone the solution of some of his most perplexing problems of 

 life and its distribution. The practical geologist has simultaneously 

 been losing faith in her monitions, and at present openly cherishes 

 the belief that the day is at hand when he can safely dispense with 

 her reluctantly accepted assistance altogether. Conscious of his 

 great inferiority to the practical geologist in the amount and re- 

 liability of his data, and disconcerted by the hazy doctrines 

 of representative forms, homotaxis, colonies, migrations and the 

 like, the palaeontologist in general is compelled to speak with a 

 diffidence that has inevitably led to the almost total neglect of his 

 opinion on geological classification. The pure stratigraphist, on the 

 other hand, certain of his facts, accepts only such of the conclusions 

 of his palaeontological brother as may happen to coincide with his 

 own, and makes his arrangements on mineralogical and stratigraphi- 

 cal data alone, in the confident assurance that " the domination of 

 Palgeontology is gone for ever." 



Perhaps no more vivid illustrations of this tendency can be seen 

 than in the beautiful map before us. Here, in one area, two for- 

 mations, hitherto held by geologist and palaeontologist alike to be 

 totally distinct, are considered as one, simply on the grounds that 

 they agree locally in physical conformity and in mineralogical 

 similarity ; although elsewhere they are separated by thousands 

 of feet of intercalated strata. In another district the apparent 

 stratigraphical evidences are so consistent that they are held to be 

 demonstrative of the co-existence in Scotland of distinct groups of 

 marine animals, which in other countries are strictly confined to 

 wholly different formations. 



The microscope of research has so magnified the geological field 

 that each formation has practically become a system, — crowded with 

 detail, and demanding a multiplicity of attainments, and a lifetime 

 of application for its proper investigation. Thus, day by day, the 

 average geologist becomes more and more of a specialist ; possessing, 

 it may be, a knowledge, more or less perfect, of that minor section 

 of his great subject which the accidents of training and locality have 



