1902.] AND ANCIENT GEOGRAPHY. 323 



islands became connected, and tlie whole was united with the conti- 

 nent of Asia; subsequently, a new (Quarternary) subsidence took 

 place. According to Weber,^ Celebes was connected in early times 

 (beginning of the Tertiary ?) with eastern Asia, but was separated 

 later and dissolved into smaller islands, and assumed its present 

 form at the end of the Tertiary. If changes of this character took 

 place during the comparatively short Tertiary period, we are to 

 expect, in Pretertiary times, much more varied conditions, and it is 

 by no means impossible that the different islands, of which certain 

 parts (for instance central Borneo) were never submerged after the 

 beginning of the Mesozoic era, were variously and repeatedly con- 

 nected with each other and the Asiatic mainland.^ Such changing 

 conditions existed probably during the whole of the Mesozoic time, 

 and it seems, on account of the scarcity of Jurassic deposits, that 

 during the Jurassic period land-conditions prevailed, although the 

 land may not have had the extent assumed by Neumayr, It may 

 have been similar during the Cretaceous period, but it seems that 

 the land bridge began to dissolve ; at least, in the Upper Cretace- 

 ous, we have positive indications that the connection between Asia 

 and Australia was interrupted. This bridge probably was never 

 again completely restored ; the single parts of it, however, were 

 not stationary in 1 ertiary times, and communicated with each other 

 in various directions. These changing conditions are noticeable as 

 far as New Guinea, and, as regards the latter island, we know 

 through Haddon, Sollas and Cole,' that it is closely connected, 

 tectonically, with Queensland. The archaic and palaeozoic rocks 

 of the '' Australian Cordilleras" continue across the islands of 

 Torres Straits into the southern part of New Guinea, which belongs 

 undoubtedly to Queensland, and was separated from it .at a very 

 recent period. On the other side, the larger Sunda Islands 

 (Sumatra, Java, Borneo) must have also been united with the 

 Asiatic mainland in very recent time, as is positively shown by 

 their fauna of higher land animals. 



1 Weber, M., Zool. Ergebn. Reise Niederlaend. Ost-Indien, Vol. 2, 1892 ; 

 Vol. 3, 1894. 



2 According to Molengraaff (^Geologische Verkenningstochten in Central 

 Borneo, iQco), Borneo was submerged in Precretaceous times, but part of it was 

 land in the Middle Cretaceous. At the end of the Cretaceous a subsidence took 

 place, then again an elevation. The different parts of Borneo were subject in 

 various degrees to these changes, which continued through the Tertiary. 



3 Trans. R, Irish Acad., Vol. 30, 1894. 



