NATURE 



97 



THURSDAY, DECEMBER 3, 1891. 



FIELD GEOLOGY. 

 Outlines of Field Geology. By Sir Archibald Geikie, 

 F.R.S. (London : Macmillan and Co., 1891.) 



GEOLOGISTS, we are sometimes told, are a com- 

 bative race. Geologists may fearlessly allow that 

 the impeachment has a spice of truth in it. They may 

 take comfort when they reflect that no serious conse- 

 quences have ever followed from this tendency, in spite of 

 the facilities which the formidable weapons they carry 

 with them offer for pushing it to an extreme. Their 

 healthy out-door life prompts banter, and the passes are 

 apt to be so quick and keen that the uninitiated may be 

 pardoned if they think the buttons are off the foils. 



The meetings of the Geological Society have witnessed 

 many a sharp passage of arms. It may be permissible 

 to recall one. A well-known member of the brotherhood, 

 safe long ago among the majority, of large and varied ex- 

 perience, was indulging in just a little brag about the 

 broad areas he had surveyed. The retort came sharp 

 and quick from one whose quips and cranks are now alas 

 heard no more : " Where are your maps ? " And the 

 contemptuous answer was, that the chief requisites for 

 geological mapping were a stout pair of legs and sound 

 wind. There were elements of truth in this lively 

 sparring, despite its extravagance. 



It is a truism that need hardly be repeated, that geology 

 cannot be learned without out-door work, and geological 

 excursions are a necessary item in all geological teaching. 

 But what do they amount to ? There is a leader who 

 knows the country well. He selects a line along which 

 sections follow one another in close succession. The ex- 

 posures are so plentiful and near together that even the 

 beginner realizes without difficulty the order in which the 

 several rock-groups follow one above the other, and there 

 are ample opportunities for mastering their lithological 

 character and fossil contents. A longitudinal section is 

 readily constructed, and figures with more or less of mis- 

 conception in the note-book of each of the party. An 

 admirable start this. But what is it compared with the 

 mental discipline that goes along with the making ot a 

 geological map, and the grip of the subject that results 

 from this form of geological work ? There is as much 

 difference between the two as between that form of sport 

 which consists in riding behind a pack of hounds who 

 follow a trailed herring, and the stalking of deer in their 

 native wilds. 



It is in mapping more than in any of its other branches 

 that geology rises to the level of an educational tool. 

 Here there must be the instinctive skill, acquired by long 

 practice, which leads the surveyor to select in his pre- 

 liminary work the traverses mo^t likely to give a broad 

 view of the structure of the district he is working over ; 

 the patience which forbids, when the first rough sketch 

 comes to be filled in, that a single square yard of ground 

 shall be left unvisited, lest some bit of evidence should be 

 missed ; and the constructive power which pieces together 

 the accumulated mass of multifarious data into a con- 

 sistent whole. Keenness of eye, neatness of hand, judg- 

 ment, unwearied application, and chastened imagination 

 NO. I I 53. VOL. 45] 



figure among the requisites for the v/ork, and grow in 

 strength as it proceeds. Surely the finishing touch in a 

 geologist's education is given by the making of a geo- 

 logical map. 



That the art cannot be learned from books alone, goes 

 without saying ; that books can do but little towards 

 teaching it, may be safely maintained. But there is no 

 reason why a master should not give us in print all the 

 aid that a book can afford, and lure us to the fascinating 

 pursuit by an eloquent description of its charms. And 

 that a book which deals with field-geology has been found 

 of service, and that geologists are not averse to hear the 

 praises of their favourite employment, are proved by the 

 fact that the little book on this subject by the Director- 

 General of the Geological Survey is now in its fourth 

 edition. 



The work is primarily addressed to geologists, but it 

 appeals also to those who have no claim to so distinctive 

 a title, and no wish for it. It shows how much pleasure 

 may be derived from an acquaintance with the science no 

 larger than any intelligent person may easily acquire ; 

 how even this moderate amount of knowledge enhances 

 the enjoyment of travel and of the daily walk. But let 

 the author speak for himself. 



" To those who are fond of country rambles geology 

 offers many attractions. Few men are so unobservant as 

 not to be struck, now and then, by at least the more 

 salient features of a landscape. Even in a flat, featureless 

 country, the endless and apparently capricious curvings of 

 the sluggish streams may occasionally suggest the ques- 

 tion why such serpentine courses should ever have been 

 chosen. But when the ground rises into undulations, 

 and breaks out into hills or crags ; still more, when it 

 towers into rugged mountains, cleft by precipices down 

 which the torrents are ever pouring, and by ravines in 

 the depths of which the hoarse streams ceaselessly 

 murmur, one can hardly escape the natural curiosity to 

 know something about these singular aspects of the 

 landscape, when and how they arose, and why they 

 should be precisely as they are." 



Our author goes on to say that " the day is now hap- 

 pily past when the sterner features of the land awakened 

 only a feeling of horror ; when they were styled hideous 

 and unsightly ; when they were never visited save under 

 the necessities of travel, and were always left behind 

 with a sense of relief." That the appreciation of the 

 beauty of mountain scenery is a taste of modern growth 

 can hardly be disputed. It is open to question whether 

 the comforts of modern travel have not done as much to 

 foster it, as a scientific curiosity to know how the forms 

 which charm our eye were produced. But, however this 

 may be, the awakening and the satisfying of such curiosity 

 are added items to the stock of pleasures which the lover 

 of Nature derives from her wilder aspects. 



Some of the inducements to field-work having been 

 thus attractively put forward, the author defines the aim 

 of the book. The student 



" must betake himself to Nature from the first. His 

 lessons in the field should accompany his lessons 

 from the text-book or lecture-room. In many cases he 

 must grope his way without guide or assistance. . . . 

 The following chapters are offered for his help. . . . 

 Their aim is to point out how observations may be made, 

 what kinds of data should be looked for, what sort of 

 evidence should be sought to establish a conclusion, and 



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