1874.] Climate of the Glacial Period. 459 
the present flora of Northern Europe lived and throve within 
about 11° of the Pole. Thus at Spitzbergen, far within 
the Arctic Circle, in lat. 78° 56’, flourished species of hazel, 
plane, poplar, lime, and beech trees, and Professor Heer 
considers that firs and poplars must at that time have 
reached to the North Pole if there was land there then for 
them to grow on. 
The strata in which this fossil flora is found within the 
Ar¢ctic Circle are believed by geologists to be of Miocene age. 
This determination is based on the fact that of 137 species 
of plants found in the Greenland beds, 46, or one-third, are 
identical with species of the Miocene flora of Central Europe. 
This fact, however, seems to me rather to be in favour of- 
the different age of the two deposits. It is improbable 
that so many species should have had such a wide range. 
We have seen that in the Eocene period Central Europe 
was occupied by a subtropical fauna and flora. Is it not 
likely that the time of the greatest heat in Europe was 
also the time of greatest heat within the Arctic Circle, and 
that, on the advent of the cooler climate of the Miocene, 
some of the species that had lived much further north 
migrated southwards into Central Europe, and took the 
place of the Eocene flora, for which the climate had then 
become too cool? In correlating the age of the arctic flora 
with that of the Miocene of Central Europe, we may be 
making the same mistake as future geologists would do if 
they assumed that the beds lying above the Cromer forest 
lived at the same time as some arctic ones now forming 
because they contain the same plants, yet the former beds 
were deposited at the very commencement of the Glacial 
period. JI amnot sure that the omission of the consideration 
of the important part that the varying climates of the 
Tertiary period played in causing the faunas and floras to 
migrate from one latitude to another may not have led to an 
exaggerated opinion of the great length of time occupied in 
forming the strata. It matters not, however, for my argu- 
ment whether the arctic flora, of which we have such 
abundant remains, was of Miocene or Eocene age. What I 
have to say has nothing to do with the existence of the 
same species at the same time in Central Europe and in 
North Greenland, but with the fact that such plants were 
able to live at all so far north. To avoid any mistake I 
prefer, however, to speak of them as Early Tertiary. 
In a paper on the Miocene flora of North Greenland read 
before the British Association in 1866, Professor Heer 
mentioned that more than sixty different species of plants 
