FOSSIL FLORA OF ALASKA. 589 



Oswald Heer and was by liim called Miocene. This flora, to which I shall again refer, has since 

 been shown by Mr J. Starkie Gardner to be Eocene. The Fort LTnion flora has many species in 

 common with the Eocene beds of the island of Mull, Bourenemouth, etc, and holds undoubtedly 

 the same position. 



On this same point Sir William Dawson says : * 



I have, also, while writing out the above notes for publication, received the paper of the same 

 author (Gardner) on the Eocene beds of Ardtun, in Mull, and am fully confirmed thereby in the 

 opinion derived from the papers of the Duke of Argyll and the late Professor E. Forbes that the 

 Mull beds very closely correspond in age with the Laramie. The Felicites hebridica of Forbes is 

 our Onoclea sensibiiia. The species of Gingko, Taxus, Sequoia and Glyptostrobus correspond, and we 

 have now probably found a Pudocarpus, as noted above. The Platanites hebridica is veiy near to our 

 great PLatanus > obilis. Corylus macquarrii is common to both formations, as well as Populus arctica 

 and P. richardnoni, while many of the other exogens are generically the same, and very closely 

 allieil. These Ardtun beds are regarded by Mr Gardner as lower Eocene, or a Utile older than the 

 Gelinden series of Saporta, and nearly of the same age with the so-called Miocene of Atanekerdluk, 

 in Greenland. Dr G. [M.] Dawson and the writer have, ever since 1875, maintained the lower Eocene 

 age of our Laramie, and of the Fort Union group of the northwestern United States, and the iden- 

 tity of their flora with that of Mackenzie river and the upper beds of Greenland, and it is very sat- 

 isfactory to find that Mr Gardner has independently arrived at similar conclusions with respect to 



the Eocene of Great Britain. 



%■ 



Dr Dall is rather more cautious in adopting the Eocene age of these beds. He 

 says : t 



I have already pointed out the probability that, if Miocene at all, the leaf beds of Greenland re- 

 ferred to would be synchronous with that geological epoch during which the old Miocene warm- 

 water invertebrate fauna of the Atlantic coast penetrated as far north as New Jersey. 



Since that time it is highly improbable that any temperate conditions such as the flora would 

 indicate for the Atane period, have obtained in the latitude of Greenland. In other words, the 

 Greenland beds are not later than the old Miocene, though this does not preclude a reference of 

 them to an older horizon than the Miocene, for during the Eocene also the conditions in the ex- 

 treme north might have been favorable to such a flora. 



In Alaska, at Cook inlet, at Unga island, at Aka, and at Nulato, in the Yukon valley, we find the 

 leaf Ijeds of the Kenai group immediately and conformably overlain by marine beds containing 

 fossil shells, which are common to the Miocene of Astoria, Oregon, and to middle and southern 

 California. 



It is then certain that the Kenai leaf beds immediately preceded and their deposition terminated 

 with the depression (probably modemte in vertical range) which enabled the marine Miocene 

 fauna to spread over part of the antecedently dry land. Further researches along the Alaskan 

 coast will doubtless enable us to determine whether the leaf beds themselves are underlain by 

 marine Eocene beds or not. We know that the Aucella beds underlie the Kenai series, but whether 

 there are any beds representing the marine phase of the Eocene between them is yet uncertain, 

 though very probable. * * * 



What may be considered as reasonably certain is tliat the period during which in the arctic re- 

 gions the last temperate flora flourished was in a general way the same for all parts of the arctic. 

 It would seem highly improbable that a temperate climate should exist in theSpitzbergen and not 

 at the same time in Greenland and Alaska, or vice versa. If Alaska was covered by the sea at this 

 time, we should find a temperate marine fauna; if it was dry land, a temperate flora; and so with 

 the. other arctic localities ; and these indications should, it would seem, represent an identical and 

 synchronic phase of geologic history in the arctic regions. 



The distribution and character of this group have been somewhat fully discussed because, up to 

 very recently, authorities were practically unanimous in referring it to the Miocene, a view which 

 cannot yet be .«aid to be definitely refuted. But when we consider how the Eocene Astoria bed is im- 

 mediately and conformably overlain at Astoria by shales and sandstones, and that the latter con- 

 formably and immediately in UHe manner overlies the Kenai group, it must be conceded that the 

 view that the latter is probably of Eocene age does not appear unreasonable. 



* Trans. Roy. See. Canada, 1887, p. 3C. 

 t Op. cit., pp. 251-252. 



LXXXII-Bui.T.. Geol. Soc. Am., Vol. 5, 1893. 



