Sept. 19, 1889] 



NATURE 



491 



left us no alternative. The interglacial beds of the Alpine 

 lands of Central Europe are paralleled by similar deposits in 

 Britain, Scandinavia, Germany, and France. But opinions 

 differ as to the number of glacial and interglacial epochs, many 

 holding that we have evidence of only two cold stages and one 

 general interglacial stage. This, as I have said, is the view en- 

 tertained by mo^t geol-^gists who are at work on the glacial 

 accumulations of Scandinavia and North Germany. On the 

 other hand. Dr. Penck and others, from a study of the drifts of 

 the German Alpine lands, believe that they have met with evi- 

 dence of three distinct epochs of glaciation, and two epochs of 

 interglacial conditions. In France, while some observers are of 

 opinion that there have been only two epochs of general glacia- 

 tion, others, as, for example, M. Tardy, find what they consider 

 to be evidence of several such epochs. Others, again, as M. 

 P'alsan, do not believe in the existence of any interglacial stages, 

 although they readily admit that there were great advances and 

 retreats of the ice during the Glacial period. M. Falsan, in 

 short, believes in oscillations, but is of opinion that these were 

 not so extensive as others have maintained. It is, therefore, 

 simply a question of degree, and whether we speak of oscillations 

 or of epochs, we must needs admit the fact that throughout all 

 the glaciated tracts of Europe, fossiliferous deposits occur inter- 

 calated among glacial accumulations. The successive advance 

 and retreat of the ice, therefore, was not a local phenomenon, 

 but characterized all the glaciated areas. And the evidence 

 shows that the oscillations referred to were on a gigantic scale. 



The relation borne to the glacial accumulations by the old 

 river alluvia which contain relics of palaeolithic man early 

 attracted attention. From the fact that these alluvia in some 

 places overlie glacial deposits, the general opinion (still held 

 by some) was that palaeolithic man must needs be of postglacial 

 age. But since we have learned that all boulder-clay does 

 not belong to one and the same geological horizon— that, 

 in short, there have been at least two, and probably more, 

 epochs of glaciation — it is obvious that the mere occurrence of 

 glacial deposits underneath palaeolithic gravels does not prove 

 these latter to be postglacial. All that we are entitled in such 

 a case to say is simply that the implement-bearing beds are 

 younger than the glacial accumulations upon which they rest. 

 Their horizon must be determined by first ascertaining the 

 relative position in the glacial series of the underlying deposits. 

 Now, it is a remarkable fact that the boulder- clays which under- 

 lie such old alluvia belong, without exception, to the earlier 

 stages of the Glacial period. This has been proved again and 

 again, not only for this country but for Europe generally. I am 

 sorry to reflect that some twenty years have now elapsed since I 

 was led to suspect that the paleolithic gravels and cave-deposits 

 were not of postglacial but of glacial and interglacial age. In 

 1871-72 I published a series of papers in the Geological Magazine, 

 in which were set forth the views I had come to form upon this 

 interesting question. In these papers it was maintained that 

 the alluvial and cave-deposits could not be of postglacial age, 

 but must be assigned to preglacial and interglacial times, and in 

 chief measure to the latter. Evidence was led to show that the 

 latest great development of glacier-ice in Europe took place after 

 the southern pachyderms and palaeolithic man had vacated 

 England ; that during this last stage of the Glacial period man 

 lived contemporaneously with a northern and alpine fauna in 

 such regions as Southern France ; and lastly, that palaeolithic 

 man and the southern Mammalia never revisited North-Western 

 Europe after extreme glacial conditions had disappeared. These 

 conclusions were arrived at after a somewhat detailed examina- 

 tion of all the evidence then available, the remarkable d'stribu- 

 tion of the palaeolithic and ossiferous alluvia having, as I have 

 said, particularly impressed me. I coloured a map to show at 

 once the areas covered by the glacial and fluvio-glacial deposits 

 of the last glacial epoch, and the regions in which the implement- 

 bearing and ossiferous alluvia had been met with, when it 

 became apparent that the latter never occurred at the surface 

 within the regions occupied by the former. If ossiferous alluvia 

 did here and there appear within the recently glaciated areas, it 

 was always either in cave=, or as infra- or interglacial deposits. 

 Since the date of these researches our knowledge of the 

 geographical distribution of Pleistocene deposits has greatly 

 increased, and implements and other relics of palaeolithic man 

 have been recorded from many new localities throughout Europe. 

 But none of this fresh evidence contradicts the conclusions I 

 had previously arrived at ; on the contrary, it has greatly 

 strengthened my general argument. 



Prof. Penck was, I think, the first on the Continent to 

 adopt the views referred to. He was among the earliest to 

 recognize the evidence of interglacial conditions in the drift- 

 covered regions of Northern Germany, and it was the reflections 

 which those remarkable interglacial beds were so well calculated 

 to suggest that led him into the same path as myself Dr. 

 Penck has published a map {Archiv fiir Anthropologie, Bd. xv.. 

 Heft 3, 1884) showing the areas covered by the earlier and 

 later glacial deposits in Northern Europe and the Alpine lands, 

 and indicating at the same time the various localities where 

 palaeolithic finds have occurred. And in not a single case do 

 any of the latter appear within the areas covered by the accumu- 

 lations of the last glacial epoch. 



A glance at the papers which have been published in Germany 

 within the last few years will show how greatly students of the 

 Pleistocene ossiferous beds have been influenced by what is now 

 known of the interglacial deposits and their organic remains 

 Profs. Rothpletz {Denkschrift d. schweizer. Gcs. fiir d. gesanimt. 

 Nat., Bd. xxviii., 1^81) and Andrew {Al>handl. z. geolog. 

 Specialkarte V. Elsass-Lothringen, Bd. iv.. Heft 2, 1884), Dr. 

 Pohlig (t>/. cit.) and others, do not now hesitate to correlate 

 with those beds the old ossiferous and implement-bearing 

 alluvia which lie altogether outside of glaciated regions. 



The relation of the Pleistocene alluvia of France to the 

 glacial deposits of that and other countries has been especially 

 canvassed. Rothpletz, in the paper cited above, includes these 

 alluvia amongst the interglacial deposits ; and in the present 

 year we have an interesting essay on the same subject by the 

 accomplished secretary of the Anthropological and ArchKO- 

 logical Congress, which met last month in Paris. M. Boule 

 correlates {Revue d\4n!hropologie, 1889, t. i.) the palaeolithic 

 cave- and river-deposits of France with those of other countries, 

 and shows that they must be of interglacial age. His 

 classification, I am gratified to find, does not materially 

 differ from that given by myself a number of years ago. He is 

 satisfied that in France there is evidence of three glacial epochs 

 and two well-marked interglacial horizons. The oldest of the 

 palaeolithic stages of Mortillet (Chelleenne) culminated, 

 according to Boule, during the last interglacial epoch, whili the 

 more recent paleolithic stages (Moust^riexne, Solutreenne, 

 and MAGDAi.fexiENNE) coincided with the last great develop- 

 ment of glacier-ice. The palaeolithic age, so far as Europe is 

 concerned, came to a close during this last cold phase of the 

 Glacial period. 



There are many other points relating to glacial geology which 

 have of late years been canvassed by Continental workers, but 

 these I cannot discuss here. I have purposely, indeed, restricted 

 my remarks to such parts of a wide subject as I thought might 

 have interest for glacialists in this country, some of whom may 

 not have had their attention directed to the results which have 

 recently been attained by their fellow-labourers in other lands. 

 Had time permitted I should gladly have dwelt upon the note- 

 worthy advances made by our American brethren in the same 

 department of inquiry. Especially should I have wished to 

 direct attention to the remarkable evidence adtluced in favour of 

 the periodicity of glacial action. Thus Messrs. Chamberlin and 

 Salisbury, after a general review of that evidence, maintain that 

 the Ice Age was interrupted by one chief interglacial epoch, and 

 by three interglacial sub-epochs or episodes of deglaciation. 

 The same authors discuss at some length the origin of the loss, 

 and come to the general conclusion that while deposits of this 

 character may have been formed at different stages of the 

 Glacial period, and under different conditions, yet that upon the 

 whole they are best explained by aqueous action. Indeed a 

 perusal of the recent geological literature of America shows a 

 close accord between the theoretical opinions of many Trans- 

 atlantic and European geologists. 



Thus as years advance the picture of Pleistocene times becomes 

 more and more clearly developed. The conditions under which our 

 old palaeolithic predecessors lived — the climatic and geographical 

 changes of which they were the witnesses — are gradually being 

 revealed with a precision that only a few years ago might well 

 have seemed impossible. This of itself is extremely interesting, 

 but I feel sure that I speak the conviction of many workers in 

 this field of labour when I say that the clearing up of the history 

 of Pleistocene times is not the only end which they have in view. 

 One can hardly doubt that when the conditions of th.at period 

 and the causes which gave rise to these have been more fully and 

 definitely ascertained we shall have advanced some way towards 

 the better understanding of the climatic conditions of still earlier 



