CHAPTER IV. 



PAST GEOGRAPHY OF THE GLOBE Continued — MIOCENE ATLANTIS — GLACIAL EPOCH. 



tTNDER the influence of the mutations in the geography of the globe which continued slowly to be 

 carried on dui-ing the eocene and miocene epochs, the faunas and floras which had been nearly 

 uniform over the whole globe, now began to break up into regional provinces. The old flora in which 

 the Australian forms predominated was extirpated in the northern hemisphere, and henceforward 

 confined to Australia, from which, in like manner, were eliminated the elements which were not 

 suited to the climate required for the other tj^es, descended from those of the eocene period. 

 Each coimtry retained (more or less altered according to the extent and nature of the change of 

 condition) the portion of the original eocene flora which suited it best, and from that starting- 

 point the difierent provinces of organic life have all gradually assimied their pi'esent places. At 

 the commencement, however, the provinces were different from what they afterwards became. 



It has been well ascertained that, in the miocene epoch, both the flora and fauna of North 

 America (although the latter in a less degree) were closely allied to those of Eiu-ope at the same 

 time ; and that, while the miocene flora of Europe has undergone an entire change, that of North 

 America has not, but retains to a certain extent the character of that which flourished there in the 

 miocene age. 



Our information upon these points in that age is fuller than upon them in the eocene. The 

 upper miocene fossiliferous beds at ffiningen, in the valley of the Rhine, between Constance and 

 Schaffhausen, have supplied a mass of material which has enabled Professor Heer of Zurich to 

 construct a miocene flora of Switzerland,* containing no less than 900 plants (which Professor 

 Oliver would reduce to SOOf), while his researches have led him to the conclusion that of phajno- 

 ganious plants alone there must have been 3000 miocene species, a much richer and more varied 

 flora than Switzerland now possesses ; and the remarkable fact is, that a large number of these be- 

 long to North American genera. M. Gaston de Saporta, in a more recent paper on the plants found 

 in the tertiary strata of the South of France, J has added considerably to the number; and the 

 united result has been to establish beyond question that a very striking resemblance, and in some 

 cases even identity, exists between the flora of the miocene epoch in Europe and the present vege- 

 tation of California and the Southern States of North America. The miocene beds of Vancouver's 

 Island and North-west America fortunately supply similarly ample material, which has been 

 investigated by M. Lesquereux, and he has satisfactorily established that the miocene flora of 

 that district is extremely similar to that still in existence there, some of the species, such as 



* " Flora Tertiaria Hclvctite," by Fiof. Oswald Hker. J G. De Saporta, in " Annalcs des Sciences Natur."' 



Winterthur, 1855-59. 1862. 



t Oliver in "Nat. Hist. Rev." 18(;2, p. 149. 



