434 



NA TURE 



[March 12, 1896 



On p. 126, "till" is distinguished from "boulder clay,' 

 and Prof. James Geikie is quoted in support of this 

 position ; but the reference is to the first or second 

 edition of the " Great Ice Age," since in the third the 

 distinction is abandoned. The third edition is quoted, 

 however, but again without exact specification, on 



p. 109. 



In describing the principal accumulations due to glacial 

 action in our islands, it would be impossible to follow all 

 the literature that has been poured forth in recent years. 

 Prof. Bonney seems to have made a fair and wide 

 selection, perhaps leaving some extreme views charitably 

 alone ; throughout, he describes rather than theorises, 

 and follows out, with steady self-denial, the line of work 

 on which he started. From p. 163 to p. 205, we have a 

 discussion of the opinions of other authors ; btit we read 

 on with a sense that behind all this exposition there is a 

 guiding mind, gently and steadily influencing our own. 

 Yet it seems that no one can complain of having been 

 misrepresented, which is about as much as Prof. Bonney 

 can hope for, when we look back on- the amenities of 

 glacial warfare. 



The description of the centres of radiation of boulders 

 of various types (pp. 151-161) would be made of singular 

 value to all students, if, in a second edition, a plate 

 showing typical microscopic sections of the rocks referred 

 to could be inserted. In this connection, we note a 

 curious remark in the foot-note on p. 140, where Ailsa 

 Craig is said to be " too small a place to have furnished 

 numerous specimens to such a distant locality." Mega- 

 scopic and microscopic examination has again and again 

 proved the occurrence of erratics of the Ailsa rock, not 

 that of Mynydd-mawr, as far south as Greystones on the 

 Irish coast, and their existence was thus proved even 

 under Mynydd-mawr itself. The very smallness of Ailsa 

 Craig may surely be adduced in favour of the view 

 that these abundant blocks have been worn away from it. 

 Of course, some of these boulders may have come from 

 the Riebeckite-eurite of Skye ; but of this there is as yet 

 no evidence. Here we touch one of the most frequent 

 paradoxes in glacial essays — boulders are assumed to 

 have come from the self-same levels where similar rocks 

 are now exposed. The frequency of the boulders them- 

 selves is a fair measure of the former extension of the 

 rock in question, even if we neglect any possible 

 differential earth-movements. 



A somewhat startling omission occurs on pp. 200 and 

 202, where what we may almost style the life-work of Mr. 

 Maxwell H. Close is attributed inadvertently to Prof 

 Hull. The wide distribution of the " sands and gravels " 

 in Ireland might perhaps have been further emphasised ; 

 but the recent observations of Prof. Sollas on Irish eskers 

 find an appropriate place in the concluding sentences of 

 this section. 



Chapter iii. of this part goes further afield, particular 

 attention being given to the wide-spread glacial pheno- 

 mena in North America. And then we find the vexed 

 "Theoretical Questions" summed up in Part III., con- 

 veniently shut in by themselves. The concluding words 

 of the chapter dealing with temperature in glacial times 

 again calls attention to the dependence of the successive 

 stages of the cold period upon the variable level of the 

 land ; and, similarly, the next chapter on the " causes of 

 NO, 1376, VOL. 53] 



a glacial epoch " closes judicially with the statement that 

 probably " some factor which is essential for the complete 

 solution of the problem is as yet undiscovered, or, at any 

 rate, the importance of one which is already known has 

 not been duly recognised." 



The final pages of this admirable book, the strength of 

 which lies largely in its reserve, point to a closer study 

 of Greenland as essential to the solution of our problems. 

 Already some comment has been made, through the latest 

 of researches, on the question raised by Prof Bonney 

 (p. 135) as to the possibility of stratification in the 

 deposits of land-ice. The spirit in which the author has 

 shown how the field is open to the future should now 

 attract a new band of workers, unfettered by their own 

 past utterances. 



Critics are most likely to lay hold of the treatment of 

 contemporary literature, when looking for a weakness in 

 this little volume. We have already indicated that the 

 exactitude of a librarian is not always noticeable in the 

 references, and various editions are not separately 

 quoted. On p. 90 the title of Mr. Whymper's book is 

 not precisely given, and the most important reference to 

 the subject is in chapter xvi., not chapter vi. — at any 

 rate, in the last edition. It is not clear from what work 

 a passage on p. 114 is quoted ; the reference should be 

 to James Geikie, "Great Ice Age," third edition, p. 171. 

 On p. 139, we might have liked a reference to some of the 

 later literature on Moel Tryfaen, perhaps to Mr. Mellard 

 Reade's examination of the microscopic materials, or to 

 Miss Andrews's record of foraminifera. The difficulty as 

 to the mingling and crossing of erratics borne by land- 

 ice (p. 171) has been to some extent met by an important 

 paper by Prof Jas. Geikie, published in the Scottish 

 Naturalist \r\ 1881, and in "Fragments of Earth-Lore" 

 in 1893. Why, again, are the figures on p. 21 quoted 

 from an abstract in the Alpine Journal^ and not from 

 Heim's own book ? The reference-figure is so placed 

 on the page as to include a calculation which seems 

 really due to Prof. Bonney. And here and there quota- 

 tions from other authors have not been checked, so that> 

 as they stand, they are not absolutely accurate. The 

 only important case of this kind, however, seems the 

 slip of " shale " for " strata " on p. 70, second line from 

 bottom. 



When,in this seemingly trivial manner, we think we have 

 found a plane of weakness in Prof Bonney's treatment of 

 " Ice-Work Present and Past," it is like pointing out 

 that David, another standard author, was injudicious in 

 discarding the full panoply of armour. The writer of 

 so many voluminous and yet precise papers in our 

 geological journals has again and again protected him- 

 self from this attack. He has displayed a generous 

 indifference as to the originality of any statement he may 

 put forth, and has thereby doubtless lost considerable 

 credit which he might otherwise have gained, as well as 

 opportunities for trenchant criticism. "If any one," he 

 wrote in 1890, "has come to conclusions identical with 

 my own, I can assure the author that there is no 

 plagiarism." In 1886, the matter was put still more 

 clearly. " If," Prof Bonney wrote, "there is any value 

 in my results, it will be that they have been obtained, as 

 far as possible, independently, and sometimes actually in 

 ignorance of the work of others." 



