DERIVATION OF THE FLORA AND FAUNA 389 



Chapter XII. 

 Antarctica as a source of the present circumpolar floras. 



Much has been written on this subject and it is not necessary to review 

 the entire hterature, which has been done already by several authors, but the 

 Antarctic problems are so important when it comes to an analysis of Juan Fernan- 

 dez that they cannot be passed in silence. J. D. Hooker was the first to survey 

 all the lands scattered around the Antarctic, Tierra del Fuego and the Falkland 

 Islands, Kerguelen Island, Tasmania, New Zealand and its subantarctic dependen- 

 cies; he was struck by the discontinuous distribution of many genera, families 

 or even species— Hemsley, i2y (a), and the author [228) have given lists of 

 such genera and species — he drew the consequences, although nothing was known 

 then about the vanished flora of the large, ice-covered continent, nor of the palaeo- 

 geography of the adjacent zone, and the idea that Antarctica had formerly ex- 

 tended farther north and that the sporadic southern islands eventually were 

 remnants of larger land masses entered his mind. Since that, the various subant- 

 arctic and austral floras have become very well known, and the cases of remark- 

 able disjunctions have multiplied. To those who adhere strictly to the hypothesis 

 of long-distance dispersal across the oceans this means nothing more than further 

 proofs that they are right, for the west-wind drift explains everything. Fortunately, 

 the land bridge between South America and Antarctica rests on solid foundation, 

 geographical as well as geological. In his important paper of 1929 [137) HOLTE- 

 DAHL has shown that the old idea of land connection between Tierra del Fuego 

 and Graham land (Palmer peninsula) by way of the Burdwood Bank, Shag Rocks, 

 South Georgia and the South Sandwich and South Orkney Islands, which had 

 been doubted by some, holds good: we have to do with a mountain range, a 

 continuation of the South American Andes, bordered by deep water which, on 

 the Pacific side, has the character of an abysmal trench but which exhibits old 

 sediments to such an extent that we are forced to postulate land where there is 

 now deep sea. The South Sandwich Islands, being entirely neovolcanic, have the 

 appearance of an "oceanic" archipelago, but they were built up during late Ter- 

 tiary times over an older foundation — a parallel to the history of Juan Fernandez 

 and of many other islands. 



It is . . . quite evident that the South Shetland land mass has once had several 

 times the width that it has to-day. . . . With their large amount of terrigenous, clastic 

 sediments etc., the South Orkneys and also South Georgia agree with the folded ranges of 

 the continent. In fact, in order to explain these masses of sediments we must necessarily 

 assume land to have been present where there is now deep sea. 



We need not assume that all the links of the Scotia or, as it is also called. 

 South Antillean Arc were united at the same time, let it be that this is possible 

 or even probable; if so, there was no communication by water between the At- 

 lantic and the Pacific, which undoutedly must have had its consequences to the 

 water circulation, a question I am quite unfit to discuss. To judge from the compo- 



