7(, AUSTRALIAN QUATERNARY CLIMATES AND MIGRATION 



the climatic belts when the tropical rain-forest reached Cape York, 

 a belt of coastal rainfall is shown extending up the coast of 

 Western Australia, as far north as Cambridge Gulf. This is 

 based on the assumptions that the average path of the lows was 

 considerably north then to where if is now, (Fig. 3) orographical 

 rainfall was intercepted by the Great Plateau of Western Aus- 

 tralia of an average height, of from 1,000 to 1,500 feet, and this 

 rainfall belt extended north across t he western end of the arid belt. 

 Several considerations arise, however, to confuse this simple 

 solution; these include the converse effect to that of the east coast 

 of the prevailing winds in the. north-west blowing from the inter- 

 ior of i\\c continent instead of from the ocean, the prevalence of 

 deserts on the west coasts of the continents, and the presence off- 

 shore of the branch of the Southern Ocean Current. That there 

 has been a wetter climate in this region is established by ample 

 evidence. Quite recently, Teichert (1946) added to this by noting 

 the presence on Iloutman's Ahrolhos, 50 miles west of (ieraldton, 

 of a rat, a variety of a species now only found on the south coast 

 and southern islands of Western Australia, also a wallaby, a 

 variety of one whose distribution does not now extend much 

 further north than Perth, As representatives of the original 

 stock are now restricted to latitudes considerably south of the 

 Ahrolhos Islands, he infers that there has been emergence and a 

 change 1 in climate — a rise in the temperature of about 5°F. 



It is evident from this review of former climatic conditions, 

 Australia north of the Murray and west, of the Great Dividing 

 Range, or precisely west of the rainfall-reliability belt, has passed 

 through periods of fertility and aridity. Regions that were 

 formerly well-watered and fertile have, with the march of the 

 climatic belts, become deserts,, and desert areas have become 

 fertile. The river valleys have been singled out because food and 

 water available along their banks during periods of fertility made 

 them attractive to migrants. This may be inferred from a state- 

 ment by Elkin (1938); 



The area of the tribal territory varies, lor the most part, with the nature 

 of the country, more especially according to its fertility and food supply. Tims, 

 on the north coast of New South Wales a narrow strip of country, roughly 300 

 miles long by sixty to ninety miles in width but well watered by rivers and a 

 good rainfall, there were several tribes on each river, numbering altogether 

 about twelve with several sub-tribes, whereas in the drier interior of the State 

 the Wiraduri alone occupied more territory than all these tribes put together. 

 Likewise, along the Queensland coast, the country along the Daly, Fitzmaurice 

 and Victoria rivers of the Northern Territory, and in the upper Murray region 

 in Victoria and New South Wales, the tribal areas were comparatively small, 

 whereas the Aranda of Central Australia occupied a large tract of country 

 si retching from about 1 lermanusburg eastwards well beyond Alice Springs and 



