266 



NA TURE 



[January 19, 1899 



which appear to have been gouged out of the bed of the 

 glacier stream, but they are all within the range of the 

 minor advances and recessions of the ice, and still leave 

 room for doubt in the minds of those who are inclined to 

 the view that most of the large fragments in the ground 

 moraine have got in from above. 



The author has long been engaged in controversy on 

 the causes and mode of operation of glacial agents, and 

 has, as is well known, pronounced views upon the 

 subject : but in a work of this kind we might have 

 expected to find not merely those facts stated which 

 support the author's theories. Yet we look in vain for 

 a sketch of the work of icebergs, floe-bergs, shore-ice, 

 pack-ice, &c., in handing on and distributing material 

 from the higher ground over wide submarine areas. 



We can hardly ignore the potent agency of ice-masses, 

 such as that seen by Ross and Parry, and estimated at 

 1,500,000,000 tons weight, in modifying the surface of 

 the land on which they grounded, and against which 

 they were driven by wind and current with a velocity far 

 greater than that attained by any glacier or ice-sheet. 



Icebergs, 700 or Soo feet high, have been seen sailing 

 along off Cape Horn, and we know that the volume of 

 ice below the water would be between eight and nine 

 times that seen above it. Not only must we take account 

 of the tremendous momentum of this stranding ice, but 

 the enormous quantity of debris now carried by floating 

 ice and distributed over the sea-bottom would seem to 

 deserve some notice. The fact calls for some explan- 

 ation, if it be a fact, that nothing of the kind is recognised 

 among the glacial deposits as having been raised from 

 the sea-bed within reach of observation. 



Towards the end of the work, where he is developing a 

 classification of forms, our author gives a separate chapter 

 on coast-lines and another on basins, which last is very 

 much a continuation of the chapters on glacial phenomena. 

 He accepts the glacial origin of most rock basins, though 

 he admits that there are difficulties in reconciling this 

 view with some of the phenomena observed in the outer 

 Hebrides, for instance fpp. 242-244). 



He describes the loess of -Southern and South-eastern 

 Russia as primarily a flood-loam of glacial times, and 

 considers that much of that occurring in the river valleys 

 of Central Europe has been derived from Alpine lands 

 (p. 192). Rut any-one who has examined the character and 

 mode of occurrence of the black, dusty Tchcrnosem of 

 Southern Russia, covering all the surface high and low, 

 continually blown away and washed away and ever 

 renewed, will have his confidence in those wide general- 

 isations as to the origin of all loess considerably shaken. 

 England is the country of all countries for the study of 

 the fossiliferous rocks ; America is too broad, .Switzer- 

 land too high ; in England the evidence is fairly com- 

 plete within easy distances, and is generally accessible. 

 -So it is in Scotland that we find the most readily available 

 epitome of the phenomena of rock-structure. It is, there- 

 fore, to be regretted that a larger portion of the illus- 

 trations were not taken from actual sections seen in 

 .Scotland or England. The work would have been more 

 valuable if the facts could have been verified in the field 

 in a sumiTier's trip. As it is there are only a dozen 

 Scotch sections, including the two excellent photographs 

 of weathered granite, and a couple from England, while 

 NO. 1525, VOL. 59] 



thirty-five of those of which the locality is given are 

 taken from foreign works. The remaining forty-two have 

 no locality — that is, are only diagrams, and those not 

 very satisfactory. 



If the glossary was intended to be confined to words 

 used in this work, there are not many which it would not 

 have been better to have explained or paraphrased in 

 the text, and most of them need no further explanation 

 than should be gained from the context ; while some need 

 not have been used at all, for it is not easy to state a 

 case in which anything is gained by using epigene and 

 hypogene instead of above-ground and under-ground. 

 Of those that do seem to require a note, some — for 

 instance, "tectonic" — are not mentioned in the glossary. 

 But if it is a general glossary to assist those who might 

 wish to follow up the line of inquiry by reading special 

 memoirs, the information is not wide enough. It might 

 have been helpful to have enabled the reader to dis- 

 criminate between diorite and syenite, dolerite and 

 basalt, and so on ; and, if the origin of the word is ex- 

 plained, to point out that diorite was so named from the 

 ease with which the component minerals could be dis- 

 tinguished as compared with dolerite which was obscure, 

 although such rough distinctions were not those upon 

 which modern petrologists rely for their classification. 



However, after cautioning our readers that there are 

 other interpretations of many of the facts observed, be- 

 sides those offered in this work, and pointing out some 

 slips which will probably be corrected in the next edition, 

 we can recommend them to read this able and clearly 

 arranged succession of essays upon an interesting group 

 of natural phenomena. 



THE OASIS OF SI IV AH. 

 From Sphinx to Oracle. By A. Silva \Vhite. I'p. xvi 

 -i- 277- 2 Maps, and 57 Illustrations. (Hurst and 

 Blackett, 1899.) 



UNDER a somewhat fantastic title Mr. A. Silva 

 White has published an account of a journey which 

 he made in the early part of the present year to the Oasis 

 of Siwah, the Oasis that was made for ever famous by 

 Alexander the Great, who visited it after he had con- 

 quered Phcenicia and Egypt. Mr. White's visit seems to 

 have been prompted by an inspiration which came upon 

 him after he had drunk deep of the " sonorous silence " 

 of the desert, at " midnight hours," " in the radiance of a 

 full-moon." We wish that the inspiration had been a 

 thing born of the day, and that it had counselled him to 

 persevere in making preparations which took the form of 

 studying the history and languages, ancient and modern, 

 of the land over which he had resolved to travel. His 

 original object seems to have been to visit Jarabub, the 

 stronghold of the powerful " Senussi " sect of Muham- 

 madans, which lies rather more than one hundred miles 

 from Siwah, in a direction more west than north- As 

 Mr- White talks of his " political studies " we may assume 

 that he had some definite mission when he set out for 

 this uninviting spot ; we have no right to inquire what 

 the mission was, and we can only offer him our sympathy 

 in his failure to reach the place where he fain would have 

 been. To this failure we perhaps owe the appearance 

 of his work. 



