78 AUSTRALIAN QUATERNARY CLIMATES AND MIGRATION 



former inhabitants have migrated to more hospitable regions but 

 the remnant has deteriorated with the increasing aridity. 



On the other hand, that part of northern Australia now within 

 the tropical rain-belt was formerly in the arid belt. It is estimated 

 that the arid belt left the Carpentaria Basin (I and II) about 

 9,000 years ago and the lower reaches of the Daly, Fitzmaurice, 

 and Victoria Rivers have been in the tropical rain-belt for 11,000 

 years. Doubtless, on the lower parts of these rivers, the popula- 

 tion has grown with their increasing fertility, brought about by 

 the march of the climatic belts. 



On the principle that the fertile tracts were the first occupied 

 11 lis deterioration and amelioration of climate suggests that those 

 which have relapsed from fertility into aridity may well contain 

 remnants of the first-comers to the mainland, while those that have 

 passed from aridity into a condition of fertility, are peopled by 

 later migrants. 



The aborigines did not wage war for territorial aggrandizement 

 (Elkin, 1938) ; their habitat was forced on them by the urge for 

 food and water, not by an aggressor. 



IX. Digest or Conclusions. 



The main submission in these notes is that the Australoids were 

 a jungle-people who entered Australia before New Guinea was 

 separated from it, in their natural environment — the tropical 

 rain-forest, or a short time before, when forest began to cover 

 what is now the Cape York Peninsula. In the last 150,000 years 

 there has not been a land-bridge connecting Australia with Asia 

 and the Proto-Indics had to cross deep channels whether they 

 came by the Celebes-New Guinea route or the Timor route. The 

 time when these geographical, climatic and environmental condi- 

 tions existed was between 15,000 and 21,000 years ago, in the early 

 Recent or Postglacial period ; the time of their entry is estimated 

 at about 18,000 years ago; this figure is based on the maximum 

 assumption of 25,000 years for the last glacial stage, but if one 

 accepts Steck's minimum estimate for this, it was as recent as 

 6,500 years ago. It is highly probable that they entered by the 

 Mid-Postglacial coastal plain (p. 67). It is thought some of the 

 aborigines of the north-west and west migrated from eastern 

 Australia, but others may have entered by the Timor route 

 (p. ante) in the last 11,000 years. 



In the east, migration southwards was along the coastal corridor 

 and the orographic rainfall-belt to fertile south-eastern Australia. 

 With the march of the climatic belts and the contraction of the 

 rainfall-reliability belt, regions that were formerly well-watered 



