1902.] AND ANCIENT GEOGRAPHY. 337 



of faults at the southern margin of the Australian Plateau indicates 

 that Australia undoubtedly extended once farther southward, in the 

 direction toward Antarctica. Whether it was really united with 

 the latter cannot be said positively, chiefly because the geological 

 structure of Wilkes' Land is entirely unknown. 



The time of the subsidence of the southern parts of the old 

 Australian continent can be determined according to the condi- 

 tions known to exist on the shores of the great Australian Bight. 

 Here, on the foot of the broken edge of the Australian Plateau, a 

 series of Tertiary deposits is found, the age of which is not yet 

 positively ascertained, but which seem to belong to both the older 

 and younger Tertiary. The fact that no older (Mesozoic) beds 

 are found in this region seems to indicate that such were not de- 

 posited, and that means to say that up to the end of the Mesozoic 

 time the southern part of the Australian Plateau had not subsided, 

 and that this process took place at the very beginning of the 

 Tertiary. 



Thus we have reason to believe that the connection of this part 

 of Australia (the western plateau) with Antarctica existed up to the 

 end of the Mesozoic time. 



The Tertiary deposits of the south coast of Australia are lacking 

 from Tasmania along the eastern coast of Australia; here is a frac- 

 ture toward the south and east, the age of which cannot be deter- 

 mined at present. Hedley believes that there was here a connec- 

 tion with Antarctica that persisted up into the Tertiary (over 

 Tasmania), but he gives no geological evidence for it. It is 

 entirely unknown whether the East Australian Cordilleras find a 

 continuation in Antarctica. So Hedley's assumption may or may 

 not be correct. 



Another tectonic line in these regions has been pointed out by 

 Gregory. 1 He also emphasizes the former southward extension of 

 the Australian Plateau ; but besides, there seems to be, according 

 to him, a very important tectonic line marked by the volcanoes of 

 New Zealand and Victoria Land, and this, possibly, finds its con- 

 tinuation in the volcanoes of the region of Graham Land, and 

 passes thence over Terra del Fuego to the South American Cordil- 

 leras. Of course, this is no evidence at all that this line from 

 New Zealand over Antarctica to South America has ever been a 

 continuous mountain range actually connecting these parts, but the 



1 Nature, Vol. lxiii, 1901, pp. 610-611, with map, p. 611. 



