124 



NATURE 



{Dec. 12, 1878 



the Mohammedan rebellion, will, no doubt, take the route 

 of Haiphong, as it is shorter than that of Pakhoi, and has 

 practicable water-communication throughout its whole 

 length. 



The latest news from Dr. Gerhard Rohlfs informs us 

 that he is at Tripoli, under the protection of the French 

 consul. He was to proceed to Wadai on December 15, 

 and was daily expecting rich presents from the Emperor 

 of Germany, which he was instructed to offer to the new 

 sultan of this remote kingdom. 



Dr. Crevaux, the explorer of French Guiana, has 

 reached the source of the Oyapok, and crossed the range 

 which separates Oyapok from the Amazon basin. 



L' Exploration, of December 7, contains several in- 

 teresting letters from M. Soleillet, who, it will be remem- 

 bered, started some months ago from the French West 

 African settlements for exploration of the African interior. 

 His last letter is dated from Kouniakary, the capital of 

 Segou, from which he hopes to reach Timbuctoo. 



Accompanying an article on the Bolan Pass in the 

 December number of the Geographical Magazine is a 

 map of the Bolan, the Mula, and other Passes, by Mr. 

 Trelawny Saunders, an admirable specimen of accurate 

 and carefully executed cartography. 



ARE THE FOSSIL FLORAS OF THE ARCTIC 

 REGIONS EOCENE OR MIOCENE ? AND ON 

 THE CA USES WHICH ENABLED THEM TO 

 EXIST IN HIGH LATITUDES ' 



npHE question of the conditions and their origin under 

 ■^ which floras, presumably requiring a temperate 

 climate, were enabled to exist in Polar regions has been 

 so frequently discussed both before and since the recent 

 Arctic Expedition, that it is strange to find any aspect of 

 the subject having remained unnoticed. 



There are some points, however, which can be by no 

 means regarded as conclusively settled, and upon these 

 I wish to say a few words. In the first place the age of 

 the so-called miocene floras has, I believe, been wrongly 

 interpreted. Again, the temperatures required by them 

 may have been over-estimated. Lastly, there seems to 

 me to be no occasion whatever to invoke astronomical 

 causes or to invent recurring periods of heat and cold, of 

 which we have no geological proof, in order to account 

 for their former presence there. 



In the first place, then, if we examine the palaeontolo- 

 gical evidence, the only kind on which the age of the 

 rocks has been decided, we find that it is very far from 

 conclusive, and instead of pointing to a common miocene 

 age for all the tertiary beds in the Arctic regions, we find 

 that there ai-e many reasons for believing some of them 

 at least to be eocene. The plant evidence is, indeed, in 

 the present state of our knowledge, almost negative ; but 

 what similarity there is in the floras to those of the 

 miocene is directly against their being of that ago instead 

 of in favour of it, /or no two floras tv/iich are nuich alike 

 and met with in widely separated latitudes can possibly 

 have been conte?npora7ieons, although floras of quite dis- 

 tinct fades may have been so. The fact that a proportion 

 of the plants have been identified by Heer with those of 

 the miocene of Switzerland is of no weight whatever, as 

 a considerable proportion are equally identified with the 

 undoubted eocene lower lignitic of America, and a number 

 of forms in the latter again with the miocene of Switzerland. 

 The truth is, that at present any formation containing dico- 

 tyledons may be, with almost equal plausibility, referred to 

 either eocene or miocene to suit the author' s requirements ; 

 for besides the similarity in the ovate and lanceolate leaves 

 from both, many species actually range right through them. 

 Were the age of the Alum Bay and Bournemouth beds 



' This was written before attention was called to Saporta's address at 

 the anniversary meeting of the Royal Society. 



not thoroughly established, from their fossil leaves, even 

 they would certainly have been referred to miocene. This 

 will not, I am happy to think, always be the case, for there 

 are a great number of plant forms which appear to be de- 

 cidedly typical of, and confined to, each stage respectively. 

 Already a number of hitherto supposed miocene deposits 

 in Europe have been recognised as eocene, and as soon 

 as those forms Avhich from their range are of negative 

 value, have been set aside, the confusion will cease. I 

 have, indeed, strong hopes that we may be able to 

 recognise each stage in the eocene of temperate latitudes 

 by its plants, more from the incoming of new and distinct 

 types, however, than the continued presence of older 

 forms. 



The confused way in which floras of many ages have 

 been mixed together, seems to me to have arisen in a 

 very simple manner. The flora of Oeningen must un- 

 doubtedly be accepted as a typical miocene flora, and 

 contains but very few eocene forms — if indeed any. It 

 contains, however, many plants common to other isolated 

 fragments of strata which contain mixed floras, that is, 

 floras with percentages of eocene as well as miocene 

 plants. There being no typical series from undoubted 

 eocene available as standards of comparison, the plants 

 common to the miocene have alone been taken to deter- 

 mine the age of these beds, and the unknown eocene 

 forms have thus been enrolled as miocene, and in their 

 turn used to identify other still more distinctly eocene 

 beds as miocene ; much in the same way that the Barton 

 beds were formerly identified, from their possessing a 

 few species in common, as London clay, and the species 

 peculiar to the Barton horizon, subsequently made use of 

 to identify calcaire-grossier and Bracklesham beds in 

 their turn with the London clay. 



The oldest Arctic flora containing dicotyledons, and 

 which, therefore, has any bearing on the subject, is that of 

 Kome in North Greenland. It is mainly composed of ferns 

 and gymnosperms, and its age may probably have been 

 correctly inferred. The next beds, referred to the upper 

 cretaceous, appear to be approximately of the same age 

 as the Dakota beds, and therefore, in my opinion, 

 decidedly supra-cretaceous relative to that formation in 

 Europe. 



We have next, if Heer's nomenclature is right, an 

 immense gap right from the cretaceous to the miocene, to 

 which latter he has referred all the rest of the obviously 

 newer beds. He does not account in any way for the 

 absence of eocene deposits, and relies exclusively on plant 

 evidence, which I think should be, for the present, abso- 

 lutely set aside. Before quitting the subject of the 

 plants, I wish it to be understood that I in no way intend 

 to disparage Heer's judgment. Considering the nature 

 and condition of the specimens submitted to him, it is a 

 marvel that he could have drawn and described them in 

 so admirable a manner. But Heer has unfortunately 

 never had a large series of definitely eocene plants to 

 describe, and hence almost all his floras are cretaceous or 

 miocene. I profoundly respect his work, and only to 

 strengthen my plea that leaf evidence may be temporarily 

 set aside or reconsidered, I mention that already three 

 floras pronounced by Heer to be miocene, have since 

 proved one cretaceous and two eocene ; and still others 

 must follow. 



Assuming that I may be allowed for the present to 

 dismiss the plants, I will touch upon the purely physical 

 evidence, which seems to me to be, small as it is, entirely 

 in favour of the eocene age of the beds. In the first place 

 we have the great probability that eocene remains would, 

 if they had ever existed, be found in their proper sequence, 

 considering the number of widely-separated places in the 

 North Polar area from which plant-remains have been 

 obtained. It is certain that they must have existed, since 

 the area continued land throughout eocene times, for 

 there are no marine deposits of that age ; and there is 



