August 15, 1878] 



NATURE 



417 



r 



which is far more abundant in Ireland than it is in England or 

 on the continent of Europe — the Megaceros — which has rightly 

 received the appellation of Hibernicus. 



I hope that we may have an opportunity, under the guidance 

 of Mr. Richard Moss, of seeing some of the remains of this 

 "antlered monarch of the waste" in the position in which they 

 were originally interred, and it will be an interesting question 

 for consideration m hether these remains can be regarded as of 

 the same geological age as those of the English caves and river- 

 gravels, or whether they do not for the most part belong to 

 what Prof. Boyd Dawkins has termed the pre-historic period. 

 It seems by no means improbable that this gigantic stag siur- 

 vived in this country for ages after he had become ;^extinct in 

 other lands, and that the view held by Prof. Hull of his ex- 

 tinction being due to persecution by man is correct. If this be 

 so it would seem to follow that the human occupation of Ireland 

 is of far more recent date than that of the sister country. 



And this brings me to one of those questions which have of 

 late been occupying the attention of geologists. I mean the 

 date which is to be assigned to the implement -bearing beds of 

 palaeolithic a^je in England. Dr. James Geikie has held that for 

 the most part they belong to an interglacial episode towards the 

 close of the glacial period, and regards it as certain that no 

 palseolithic bed can be shown to belong to a more recent date 

 than the mild era that preceded the last great submergence. 



His follower, Mr. Skertchley, records the finding of palaeo- 

 lithic implements in no less than three interglacial beds, each 

 underlying boulder clays of different ages and somewhat dif- 

 ferent characters, the Hessle, the purple, and the chalky boulder 

 clay. This raises two main questions, first, as to how far Dr. 

 Croll's theory of the great alternations of climate during the 

 glacial period can be safely maintained ; and secondly, how far 

 the observations as to the discovery of implements in the so- 

 called Brandon beds underlying the chalky boulder clay can be 

 substantiated. Another question is how far the paleeolithic de- 

 posits can be divided into those of modern and ancient valleys, 

 separated from each other by the purple boulder clay, and the 

 later of the two older than the Hessle beds. It would be out 

 of place here to discuss these questions at length. I will only 

 observe, that in a considerable number of cases the gravels con- 

 taining the implements can be distinctly shown to be of much 

 later date than the chalky boulder clay, and that if the imple- 

 ments occur in successive beds in the same district, each separated 

 from the other by an enormous lapse of time, during which the 

 whole country was buried beneath incredibly large masses of 

 invading ice, and the whole mammalian fauna was driven away, 

 it is a very remarkable circumstance. It is not the less remark- 

 able because this succession of different palceolithic ages seems 

 to be observable in one small district only, and there is as close 

 a resemblance between the instruments of the presumably dif- 

 ferent ages as there is between those of admittedly the same 

 date. I have always maintained the probability of evidence 

 being found of the existence of Man at an earlier period than 

 that of the post-glacial or quaternary river gravels, but, as in all 

 other cases, it appears to me desirable that the evidence brought 

 forward should be thoroughly sifted and all probability of mis- 

 apprehension removed before it is finally accepted. In the 

 present state of our knowledge, I do not feel confident that the 

 evidence as to these three successive palaeolithic deposits has 

 arrived at this satisfactory stage. At the same time is must be 

 borne in mind that if we make the palaeolithic period to embrace 

 not only the river gravels but the cave deposits of which the 

 south of France furnishes such typical examples, its duration 

 must have been of vast extent. 



In connection with the question of glacial and interglacial 

 periods, I may mention that of climatal changes in general, 

 which has formed another subject to which much attention has 

 of late been given. The return of the Arctic Expedition, and 

 the reports of the geological observations made during its progress, 

 which have been published by Captain Feilden, one of the 

 naturalists to the expedition, in conjunction with Mr. De Ranee 

 and Prof. Heer, have conferred additional interest on the 

 question of possible changes in the position of the poles of the 

 earth, and on other kindred speculations. Near Discovery 

 Harbour, about latitude 81° 40', miocene beds were found- con- 

 taining a flora somewhat differing from that which was abeady 

 known to exist within the Arctic regions. " The Grinnell Land 

 lignite," say the authors of the report, "indicates a thick peat 

 moss, with probably a small lake, with water-lilies on the surface 

 of the water, and reeds on the edges, with buxhes, poplars, and 



taxodiums on the banks, and with pines, firs, spruce, elms, and 

 hazel-bushes on the neighbouring hills." When we consider 

 that all of the genera here represented have their present limits 

 at least from twelve to fifteen degrees further south, while 

 the taxodium is now confined to Mexico and the south of the 

 United States, such a sylvan landscape as that described seems 

 entirely out of place in a district within six himdred miles of 

 the pole, to which indeed, if land then extended so far, these 

 Arctic forests must have also extended in miocene times. 

 Making all allowance for the possibility of the habits of such 

 plants being so changed that they could subsist without sunlight 

 during six months of a winter of even longer duration, I caimot 

 see how so high a temperature as that which appears necessary, 

 especially for the evergreen varieties, could have been main- 

 tained, assuming that Grinnell Land was then as close to the 

 North Pole as it is at the present day. Nor is this difficulty 

 decreased when we look back to formations earlier than the 

 miocene, for the flora of the secondary and palaeozoic rocks of 

 the Arctic regions is identical in character with that of the same 

 rocks when occurring twenty or thirty degrees farther south, 

 while the corals, encrinites, and cephalopods of the carboni- 

 ferous limestone are such as, from all analogy, might be sup- 

 posed to indicate a warm climate. 



The general opinion of physicists as to the possibility of a 

 change in the position of the earth's axis has recently undergone 

 modifications somewhat analogous in character to those which, 

 in the opinion of some geologists, the position of the axis has 

 itself undergone. Instead of a fixed dogma as to the impossi- 

 bility of change, we find a divergence of mathematical opinion 

 and variations of the pole differing in extent, allowed by different 

 mathematicians who have of late gone into the question, as, for 

 instance, the Rev. J. F. Twisden,i Mr. George Darwin,^ Prof. 

 Haughton,3 the Rev. E. Hill,* and Sir William Thomson.^ All 

 agree in the theoretical possibility of a change in the geo- 

 graphical position of the earth's axis of rotation being effected 

 by a redistribution of matter on the surface, but they do 

 not appear to be all in accord as to the extent of such 

 changes. Mr. Twisden, for instance, arrives at the conclu- 

 sion that the elevation of a belt twenty degrees in width, 

 such as that which I suggested in my presidential address 

 to the Geological Society in 1876, would displace the axis by 

 about ten miles only, while Prof. Haughton maintains that the 

 elevation of two such continents as Europe and Asia would dis- 

 place it by about sixty-nine miles, and Sir W. Thomson has not 

 only admitted, but asserted as highly probable, that the poles 

 may have been in ancient times ' ' very far from their present 

 geographical position, and may have gradually shifted through 

 ten, twenty, thirty, forty, or more degrees without at any time 

 any perceptible sudden disturbance of either land or water." 



I am glad to think that this question, to which I to some 

 extent assisted to direct attention, has been so fully discussed, 

 but I can hardly regard its discussion as being now finally 

 closed. It appears to me doubtful whether eventually it will be 

 found possible to concede to this globe that amount of solidity 

 and rigidity which at present it is held to possess, and which, 

 to my mind at all events, seems to be in entire disaccordance 

 with many geological phenomena. Yet this, as the Rev. O. 

 Fisher^ has remarked, is presupposed in all the numerical 

 calculations which have been made. I am also doubtful whether 

 in the calculations which have been made, sufficient regard has 

 been shown to the fact that a great part of the exterior 

 of our spheroidal globe consists of fluid which, though of 

 course connected with the more solid part of the globe by 

 gravity, is readily capable of readjusting itself upon its siur- 

 face, and may, to a great extent, be left out of the account in 

 considering what changes might arise from the disturbance of 

 the equilibrium of the irregular spherical or spheroidal body 

 which it partially covers. It appears to me also possible that 

 some disturbances of equilibrium may take place in a mysterious 

 manner by the redistribution of matter or otherwise in the 

 interior of the globe. Capt. F. J. Evans,^ arguing from the 

 changes now going on in terrestrial magnetism, has suggested 

 the possibility of some secular changes being due to internal, 

 and not to external causes ; and it really be true that there is a 

 difference between the longest and shortest equatorial radii of 



I Quart- Joum. Ceol. Soc, 1878, p. 35. 



^ Proc. R. S., vol. XXV. p. 328. Phil. Trans., clxvii. p. syr. 



3 Proc. R. S., 1877, 1878. ■* Geol. Mag., June, 1878. 



5 Rep. Brit. Assoc, 1876, p. II. ^ Geol. Mag., IwXytZ'&iZ. 



' Nature, vol. xvlii. p. 80. 



