June 22, 191 1] 



NATURE 



549 



thought he was after fees, and it would be to his in- 

 terest to reduce work by keeping in touch at all 

 times with the people for whose health he is respon- 

 sible. He would at the same time act as an educat- 

 ing influence, and the absence of the dread of a fee 

 to pay would further promote early treatment. 



GEOLOGY FOR STUDENTS. 

 A Text-Book of Geology. By P. Lake and R. H. 

 Rastall. Pp. xvi + 494. (London : E. Arnold, 1910.) 

 Price 16^. net. 



THIS text-book will fill the gap between several 

 excellent books of a more primary character and 

 the great English work of reference which we owe 

 to Sir Archibald Geikie. Mr. Rastall is responsible 

 for the physical portion, and Mr. Lake for that deal- 

 ing with stratigraphy. 



Dr. J. E. Marr, as editor of "Arnold's Geological 

 Series," to which the work belongs, states in his 

 preface that 



" the stratigraphical portion of the book is occupied 

 almost entirely with the study of the stratigraphy of 

 the British Isles, which is sufficient for the purposes 

 of elementary teaching." 



This, however, is just the point on which there may 

 be most difference of opinion. It may seem to some 

 of us that in elementary teaching a view of the earth's 

 history should be imparted on the broadest scale. 

 The gaps in our insular stratified series should be 

 filled in unhesitatingly from other lands. The pro- 

 gress of living things from Palaeozoic to Quaternary 

 types can be followed with interest even by a be- 

 ginner in geology; but few people can take delight in 

 British genera and species unless they can picture 

 them in a setting of the successive faunas of the 

 globe. The early editions of Lyell's " Principles of 

 Geology " are appealed to by Dr. Marr as an example, 

 yet nothing is more prominent in Lyell's work than 

 his desire to establish a stratified sequence by observa- 

 tions made in many lands. Consider his table of 

 " Recent and Tertiary Formations," on p. 61 of his 

 third volume, published in 1833, and compare it with 

 Mr. Lake's treatment of the same formations on 

 pp. 439 and 453 of this modern text-book. Lyell, 

 with a fascinating sweep, reminds us in his table of 

 the delta of the Ganges, of Uddevalla, of Asti, and 

 Perpignan, of the Supcrga, and of the volcanoes of 

 the Velay. On p. 46 he regrets his ignorance of 

 "many deposits known to exist in Spain and Por- 

 tugal." 



Many of us still share Lvell's re-grot, not ])rc;uise we 

 want to carry in our heads the list of fossil species 

 found on particular horizons, but because we want 

 to fit the beds into the general scheme of stratified 

 deposits. Lyell took his marine fossils as "medals 

 which nature has chiefly selected to record the history 

 of the former changes of the globe." Our universi- 

 ties, since his time, have established the cult of zones 

 and horizons within the British Isles. The British 

 Isles, moreover, have been accepted as consisting of 

 England and Wales, and attention has become more 

 and more concentrated on a limited area of the 

 European outpost. Mr. Lake has worked well under 

 NO. 2173, VOL. 86] 



these conditions, and no one will accuse him of ignor- 

 ance of the wider aspects of the earth. We expect, 

 however, a " text-book of geology " to convey to us 

 some picture of the progress of life upon the globe. 

 Of this we find only scanty traces in the 200 pages 

 devoted to stratigraphical geology. The word " strati- 

 graphical " has been allowed to dominate this section 

 rigidly. In this respect numerous smaller text-books 

 come nearer to the Lyellian conception of geology. 



Mr. Lake's treatise, however, is indispensable for 

 those who wish to bring their knowledge of British 

 strata up to date. He has included, for instance, 

 Mr. J. F. N. Green's revision of the St. David's area 

 (p. 298) ; the probability of an unconformity in the 

 Bala series, emphasising its division into Caradocian 

 and Ashgillian (pp. 318 and 320); and Mr. Clement 

 Reid's assignment of an Upper Oligocene age to the 

 plant-beds of Bovey Tracey (p. 452). 



A Scottish geologist may be provoked to find that 

 the rocks which form the main mass of his highlands 

 are described in six lines (p. 297). An Irish geologist 

 will regret that the Dingle problem is dismissed in 

 twenty-six words (p. 352), while the Lower London 

 Tertiaries occupy two noble pages. But tliis lack of 

 proportion is written large in the programmes of our 

 public examinations. 



Mr. Rastall's chapters on physical geologfv naturally 

 make a wider appeal. Even the Dwyka conglomerate 

 of South Africa is shown in one of the photographic 

 plates, though no explanation appears to be given of 

 its remarkably interestiitg character's. Spitsbergen 

 and Alaska are well referred to, and the Tonga 

 Islands, the great cone of Misti, and the wind-scored 

 Sphinx, are used as illustrations of features that have 

 a broad significance. The plates are chosen with 

 much care, and the diagrams are as lucid as the 

 accompanying text. Good examples of the author's 

 treatment are to be found in the passages on desert- 

 erosion (p. 69), and on river-capture (p. 45). Where 

 so many physical matters have to be dealt with, few 

 authors will agree as to the degree of prominence. to 

 be given to each. We should have liked to hear 

 more of the many varieties of gneisses, and we note 

 that the author regards thermal metamorphism as 

 "usually of comparatively limited extent," a state- 

 ment tiiat is true enough of the rocks exposed in 

 England. In the Transvaal, Rhotlcsia, Fennoscandia, 

 and Canada, examples of a very different order may 

 be found. Rock-cleavage is clearly described, and is 

 illustrated by plates iv. and v., which might well be 

 transferred, with their text, to the chapter on meta- 

 morphism two hundred and forty pages further on. 



Mr. Rastall shows as much caution (pp. 100, loi, 

 &c.) in dealing with the work of ice as his colleague 

 does (p. 464) in dealing with the glacial epoch ; but 

 the main results of observation are very fairly stated, 

 and the lessons of Arctic lands arc applied to the 

 British Isles. Is Spitsbergen, however, to be de- 

 scribed (p. 99) as "a region of heavy precipitation" ? 

 Where the actual amount of melting is slight, 

 glaciers, fed by broad snow expanses, can be main- 

 tained in an almost arid climate. 



In this excellently produced book we have come 

 across no misprints. " Porphyn,-," in the table on 



