REPORT OF THE DIRECTOR I92O-2I IOQ 



basement complex may be either independent, or may have been 

 a further extension of either of the two others. 



The fact that Cambrian deposits are entirely lacking upon central 

 Aequinoctia, but can be found leaning against it in the north (see 

 Abendanon, p. 577), is in itself evidence that this Paleozoic con- 

 tinent extends backward into Precambrian time as a land mass. 

 Schuchert's chart shows this continent, in Cambrian time to have 

 extended from northern Siam and Cochinchina across the entire 

 East Indian Archipelago to eastern Australia and New Zealand. 

 It is separated from the Indian peninsula by the Cambrian invasion 

 from China and from western Australia by the Cambrian trans- 

 gression of middle Australia. Its extension toward the Pacific 

 as pointed out by Abendanon is unknown. 



As the Cambrian transgressive beds rest in Asia and Australia 

 not on a transitional series from Precambrian to Lower Cambrian 

 beds such as have been asserted to have been found in parts of the 

 Rocky mountains, but the contact is distinctly unconformable, it 

 is clear that the Precambrian ancestor of Aequinoctia was connected, 

 at least in the last period of the Precambrian, by land with . the 

 Indian peninsula and West Australia. The latter two have, however, 

 been shown before to have probably formed an entity with Africa 

 and Madagascar as indicated by the predominant north-south strikes 

 of their Precambrian rocks. One may, therefore, well ask himself 

 whether the east-west strike of the Precambrian rocks is not of 

 later than Precambrian age and thus no criterion for the Precambrian 

 independence of this Paleozoic continental mass. 



As the East Indian Archipelago was. not invaded until the Car- 

 boniferous period, the folding may have taken place at any time 

 during the preceding part of the Paleozoic era. The mountain 

 folds of eastern Australia from Tasmania northward, have Cambrian, 

 Ordovician and Devonian beds folded in with the Precambrian 

 rocks, and these mountain folds while striking north-south in south- 

 eastern Australia, turn northwest and finally east-west as they 

 approach the East Indian Archipelago, as we have seen before. 

 We believe that this fact suggests a Precarboniferous Paleozoic 

 age for the initiation of the east-west fold system of the Archipelago 

 that may have been so powerful that it involved the Precambrian 

 basement complex and overpowered and obliterated* the earlier 

 strike directions, as has been done in other younger fold systems. 



The east- west direction of the Precambrian rocks extending from 

 Borneo to New Guinea is repeated (see Abendanon, p. 567, footnote) 

 in the isle of Java, and in the chain of the small Sunda islands. 

 Therewith, however, it seems to fall in with the general sigmoidal 



