496 ISLAND LIFE part ir 



enormous stretch of Cretaceous and Tertiary formations 

 extjending from the Gulf of Carpentaria completely across 

 the continent to the mouth of the Murray River. During 

 the Cretaceous period, therefore, and probably throughout 

 a considerable portion of the Tertiary epoch,i there must 

 have been a wide arm of the sea occupying this area, 

 dividing the great mass of land on the west — the true seat 

 and origin of the typical Australian flora — from a long but 

 narrow belt of land on the east, indicated by the continuous 

 mass of Secondary and Palaeozoic formations already 

 referred to whicli extend uninterruptedly from Tasmania 

 to Cape York. Whether this formed one continuous land, 

 or was broken up into islands, cannot be positively 

 determined ; but the fact that no marine Tertiary beds 

 occur in the whole of this area, renders it 23robable that it 

 was almost, if not quite, continuous, and that it not 

 improbably extended across to what is now New Guinea. 

 At this epoch, then (as shown in the accomj^anying map), 

 Australia may, not improbably, have consisted of a verj^ 

 large and fertile western island, almost or quite extra- 

 tropical, and extending from the Silurian rocks of the Flin- 

 ders range in South Australia, to about 150 miles west of the 

 present west coast, and southward to about 350 miles south 

 of the Great Australian Bight. To the east of this, at a 

 distance of from 250 to 400 miles, extended in a north and 

 south direction a long but comparatively narrow island, 

 stretching from far south of Tasmania to New Guinea ; 

 while the crystalline and Secondary formations of central 

 North Australia probably indicate the existence of one or 

 more large islands in that direction. 



The eastern and the western islands — with whicli we are 

 now chiefly concerned — would then differ considerably in 

 their vegetation and animal life. The western and more 

 ancient land already possessed, in its main features, the 



^ From a,n examination of the fossil corals of the South-west of Victoria, 

 Professor P. M. Duncan concludes—" that, at the .time of the formation of 

 these deposits the central area of Australia was occupied by sea, having 

 open Avater to the north, with reefs in the neighbourhood of Java." The 

 age of these fossils is not known, but as almost all are extinct species, and 

 some are almost identical Avith European Pliocene and JMiocene species, 

 they are supposed to belong to a corresponding period. {Joitrnal of Gcol. 

 Soc, 1870.) 



