December 24, 1914] 



NATURE 



451 



THE QUATERNARY ICE AGE.^ 



THIS handsome volume is a notable contribu- 

 tion to the voluminous literature relating- 

 to glacial geology. Its scope is comprehensive, 

 for it describes in a crisp and lucid form the 

 succession of Glacial and post-Glacial deposits 

 in Europe and North America, the living and 

 extinct Quaternary mammals, the successive 

 stages of culture of Palaeolithic and Neolithic 

 man, the various theories of the cause of the 

 Ice age, and the isostatic theory of the Quater- 

 nary oscillations of sea-level. Much controversial 

 g-round is traversed in this wide field. Throug^h- 

 out the volume the author maintains a critical 

 attitude and expresses his opinions freely. His 

 chief aim has been to set forth what he regards 

 as the solid basis of fact which throws light on 

 the history of this fascinating epoch. Hence he 

 discards classifications which, in his opinion, arc 

 not supported by conclusive evi- 

 dence. 



At the outset the potency of 

 g^lacial action in modifying the 

 surface features of a country is 

 recognised. In proof of this con- 

 tention reference is made to the 

 over-deepening of valleys, the 

 formation of mountain corries, 

 the recession of corrie cliffs by 

 sapping, and the excavation of 

 rock basins due to differential 

 erosion in harder and softer 

 rocks. In the preliminary ac- 

 count of the Glacial drifts the 

 opinion is expressed that many 

 erroneous conclusions regarding 

 the retreat and re-advance of the 

 ice and the occurrence of inter- 

 Glacial periods have been based 

 on intercalations of sand, gravel, 

 and clay between sheets of 

 Boulder Clay. The so-called 

 *' Upper Boulder Clay," in many 

 instances, may be merely en- 

 glacial moraine, which settled 

 down on sub-glacially-formed sediments on the 

 disappearance of the ice. On the other hand, it is 

 admitted that, where these intercalated deposits 

 preserve their horizontality over wide areas, they 

 probably point to retreat and re-advance of the 

 ice. Their inter-Glacial value must be determined 

 by local circumstances. 



The author's attitude towards the inter-Glaciai 

 question is clearly defined. He is of opinion that 

 the elaborate systems of the older inter-Glacialists 

 may all be set aside as unproved, and that we 

 ought to accept the mono-Glacial hypothesis until 

 we can prove one inter-Glacial period. Never- 

 theless instances are adduced which prove 

 oscillations of climate of more or less magnitude. 

 The recent researches of Victor Madsen, Nord- 

 mann, and Harz on the Cyprina Clays of Den- 

 mark, North Germany, and Holland, furnish 



1 "The Ouaternary Ice Age." By W. B. Wright. Pp. xxiv+464. 

 <London : Macmillan and Co., Ltd., 1914-! Price 17J. net. 



NO. 2356, VOL. 94] 



satisfactory evidence. These fossiliferous de- 

 posits occur as transported masses in the Boulder 

 Clay in the east of Denmark and north of Ger- 

 many, while to the west and south of these areas 

 they are to be found in their original position, 

 resting- on Boulder Clay and fluvio-Glacial g-ravels. . 

 Therefore they cannot be pre-Glacial. They must 

 have been laid down during a period of recession 

 of the ice. In view of the. width of the belt con- 

 taining transported masses of these Eemian 

 deposits in the Boulder Clay of the Baltic ice 

 sheet, the extent of the recession cannot be less 

 than fifty miles. But the presence of well-marked 

 southern species in the marine fauna may indicate 

 a greater recession, and probably the complete 

 disappearance of the ice. These investigations 

 confirm the opinion of Prof. James Geikie and 

 others who assigned these deposits to an inter- 

 Glacial period. 



The series of Glacial and inter-Glacial periods 



Fig. I. — The .Arctic Fox (VuiJ>es lagopus) in winter c'lat. From a specimen in the Britiiih 

 Musenm. From " The Quaternary Ice -Age.' 



worked out by Penck and Bruckner in the Alps 

 is adopted. Special allusion is made to certain 

 inter-Glacial deposits proving- oscillations of 

 climate, such as the " Hottinger Breccia," the 

 " Schieferkohlen " of Diirnten, the plant-bearing 

 beds of Re and Pianico, all of which are doubtfully 

 referred to the Riss-\\'urm inter-Glacial period. 

 It is further shown how the evidence from plant 

 remains is confirmed by the Quaternary fauna 

 occurring in .Alpine lands ; the twofold repetition 

 of the arctic fauna comprising the mammoth, 

 woolly rhinoceros, and reindeer, being- separated 

 bv the inter-Glacial fauna with Elephas aiitiqiius, 

 Merck's rhinoceros, and the red deer. 



In the description of the .American drifts the 

 classification presented is not so comprehensive as 

 that of Prof. Chamberlin. It begins with the 

 Kansan Till sheet and ends with the later \\'is- 

 consin Boulder Clay. The cautious attitude of the 

 author in dealine with the classic Don vallev 



