August i6, 1906J 



NA TURE 



3«9 



European Gl.acul and Interglacial Stages (Prof. J. 

 Geikie). 



: Sixth Glacial Teriocl ' 

 = Fifth Interglacial Period ' 

 = Fifth Glacial P^poch 

 = Fourth Interglacial Epoch 

 : Fourth (Ibcial Epoch 

 = Third Interglacial Epoch 

 = Third Glacial Epoch 

 = Second Interglacial Epoch 

 : Second Glacial Epoch 

 = First Interglacial Epoch 

 = First Glacial Epoch 



But although, as already mentioned, the Interglacial 

 hypothesis in its simpler form has many supporters in this 

 country, I do not think that the above scheme in its 

 entirety has yet found any adherents among British 

 glacialists. Usually, when beds supposed to be of inter- 

 glacial age have been described by other workers, it has 

 been implied that only a single interval of milder con- 

 ditions was in mind ; and even in the exceptional cases 

 where several different boulder-clays separated by sand 

 aiW gravel have been held to represent as many different 

 epochs of glaciation, it is rare that any attempt has been 

 made, except by Prof. Geikie himself, to classify the sup- 

 posed events in accordance with the scheme. I suppose 

 that most field-workers have felt, like myself, that whi'e 

 some part of the classification might possibly be sustained, 

 this finished arrangement of the admittedly imperfect 

 evidence was too artificial to be accepted with confidence, 

 and that it was inadvisable to allow one's self to be 

 hampered, in an inherently difiicult task, with further 

 ditViculties that, after all, might, like " the word Bear- 

 baiting," be "carnal and of man's creating." 



On the other hand, partly, no doubt, from the persuasive 

 manner in which its author has presented his case and 

 his courteous readiness to meet objections, but still more 

 from the vast extent of the field drawn upon for the argu- 

 ment, the scheme has aroused less active criticism than 

 it has, in my opinion, deserved. The critic has shrunlc 

 from the magnitude of the task of testing it in all its 

 parts, while to pick out the local flaws in any particular 

 part has seemed invidious. 



In taking this scheme as the basis of my examination 

 into the evidence, I am aware that the local limitations 

 which I have set myself will be held to impair the validitv 

 of my conclusions. But as there is at present in every 

 glaciated country the same confusion of opinion on the 

 Interglacial problem as in our own, and the same dis- 

 cussion upon the fundamental value of the evidence, it 

 appears to me that we can find strong justification for 

 considering our own problem on its separate merits. And 

 the necessity for a re-sifting of the British evidence is the 

 more urgent since it is frequently taken for granted in 

 the discussions abroad that there is a well-established 

 glacial sequence in Britain, which can be called in to 

 support the argument for other lands. 



The Interglacial Problem in Other Countries. 



It will serve to illustrate the condition of the problem 

 in other countries if I refer briefly to some of the literature 

 which happens to have come under my notice, though I 

 can rarely claim sui^cient knowledge of the foreign work 

 to discuss its value. 



Norway. — In Norway there appears to be no direct 

 evidi nee for interglacial epochs, though the existence of 

 one such epoch is supposed to be indicated by a change 

 in the direction of ice-flow, and by the presence of an 

 arctic flora at the base of the Danish peat-mosses which 

 is absent in Norway. By Dr. A. M. Hansen - the super- 

 ficial deposits are classed as follows : — preglacial : protero- 

 glacial : interglacial : deuteroglacial : and postglacial. 



Su'L'den. — In Sweden, and, I believe, also in Denmark, 

 the Interglacial hypothesis is generally accepted, at least 

 to the extent of one epoch of deglaciation, but is strenu- 



1 ' ■ Period " in original ; (?/. ci/. : probably r 

 = A. M. Hansen, " The Glacial Su 

 vol. ii. (189^), pp. 123-144. 



NO. 1920, VOL. 74] 



ously opposed by Dr. N. O. Hoist, who states his convic- 

 tioni based on the result of his observations in Greenland, 

 that the so-called interglacial sands and gravels and the 

 " upper moraine ' of Sweden represent the residual pro- 

 ducts of the ice-sheet that laid down the " lower moraine " 

 as a ground-moraine. He also embraced the drifts of 

 North Germany in this explanation.' 



Germany, — In Germany, the discussion on the " Inter- 

 glacialismus " is still in active progress. The idea of one 

 interglacial epoch, corresponding to the " Helvetian " of 

 Prof. J. Geikie's scheme, is widely entertained; and some 

 geologists, influenced largely by evidence in the Alps, think 

 that an earlier interglacial stage ( = " Norfolkian "), pre- 

 ceded by a stage of glaciation ( = " Scanian "), may have 

 to be admitted, though the German evidence is acknow- 

 ledged to be imperfect. But Prof. Geikie's interpretation 

 of the North German drifts, on which he seeks to establish 

 the " Neudeckian Interglacial " and the " Mecklenburgian 

 Glacial " epochs, is strongly and authoritatively opposed. 

 In a searching criticism of these views Dr. K. Keilhack, 

 of the Prussian Geological Survey,- states that no reason 

 has been found, by himself or his colleagues, for the pro- 

 posed separation of the upper drifts into these separate 

 epochs ; and he remarks that, on similar grounds, " the 

 so-called ' last glacial epoch ' would have to be divided 

 into four if not five epochs, so that even the most fanatical 

 advocate for as many glacial periods as possible would be 

 terrified." Prof. Geikie, in his reply to this criticism.' 

 brings forward the British evidence to establish the case 

 in Germany. But, as we shall see, this evidence is 

 especially weak, and we in this country had expected that 

 the stronger proof lay in Germany. 



While the supporters of the " Interglacialismus " are 

 thus uncertain how much of the scheme they will accept, 

 there are other geologists in Germany who repudiate the 

 hypothesis in its entirety, and hold for the " singleness 

 of the Ice-Age." Among these I may mention Prof. E. 

 Geinitz,' whose vigorous attack has been supported by Dr. 

 W. Wolff, in a useful summary of the discussion, which 

 contains many references to the literature." 



Russia. — In Russia, again, opinion is divided, and the 

 evidence brought forward in favour of the Interglacial idea 

 has been adversely criticised by Mr. S. Nikitin; of the 

 Russian Geological Survey," who considered that, what- 

 ever may have been the conditions farther westward, 

 oscillations of the ice-margin would suffice to explain the 

 facts observed in this outer portion of the glaciated area. 



The Alps. — In the Alps there appears to be definite 

 evidence for several periods of advance of enormous 

 glaciers from the mountain valleys, with intervening 

 periods of great recession, and these are supposed to 

 correspond to glacial and interglacial epochs in Northern 

 Europe; but there has been much difference of opinion 

 respecting this evidence and its interpretation. By Profs. 

 .'\. Penck and E. Briickner. who have systematically 

 investigated the phenomena, the ice-movements are held 

 to indicate four separate epochs of glaciation, with three, 

 or perhaps four, warm interglacial epochs.' Not having 

 yet found an opportunity to make myself sufficiently 

 acquainted with the evidence, I may not fully recognise 

 its importance; but it appears to me that the factors 

 governing the glaciation of this .Alpine region may have 

 been very different from those that controlled the lowland 



1 " Har det fannits mera an en istid i Sverije." Svtyifcs Ceolosrhka 

 Uniicrsilkmn^, .Ser. C. No. 151 (iSoO: and "On the Relations of the 

 'Writing Chalk' of Tullstorp (Sweden) to the Drift Deposits with 

 Reference to the Interglacial Question." Geol. Mag., dec. v., vol. i. (1904), 

 pp. 56-59. 



■- Prof. Geikie's Classification of the North European Glacial Peoosits," 

 fourn. Geol.. vol. v. (1807), pp 113-135. See also discussion by H. Munthe : 

 " Studien iiher iiltere Quart-urablacerungen im siidbaltischen Gebiete." 

 B:ill. Geol. Imtit. Vpsnla. vol. iii. No. 5 (1S96), pp. 27-i'4- 



3 "The Last Great Baltic Glacier." Journ. Geol., vol. v. (1897), pp. 

 324 -■539. 



■* '■ Die Einheitlichkeit der quartaren Eiszeit." Neuesjakrb.j. Mineral- 

 ogle, &c., xvi. (1902), pp. 1-98. and other papers. 



5 "Zur Kritik der Interglacial-Hypothese. " Naluili'iss. WocJunschrift. 

 Neue Folge, Bd. ii. No. 26 (1903), T4 pp. 



^ " Sur la constitution des d^puts quaternaires en Russia, Sic." Rep. 

 Congyis tntcmat. a'Arelieologie," Moscou. 1892. 



~ Die Alpen im Eiszeitalter.'* Leipzig (1^01-5), not yet complete; for 

 convenient summary see " Glazialexkursion in die Ostalpen." No. 12 of 

 " Guides to Excursions of the Geological Congress," Vienna, 1903. 



