30 AUSTRALIAN QUATERNARY CLIMATES AND MIGRATION 



VII. Critical millennia. 



VIII. Migration routes in Australia. 



IX. Digest of conclusions. 



As far as possible, the writer has restricted his comments to 

 the geology of deposits in south-east Australia containing arte- 

 facts, the climates implied by such deposits, and the palaeogeog- 

 raphy at critical periods. Where references are made to social 

 anthropology, their sources are given. 



IVTP71 



h,"l'i Rainfall-reliability Belt 



FIG. 2. 

 Climatic Belts and Rainfall-reliability Belt at the Postglacial Optimum. 



(1). March of the Climatic Belts. 



In Australia during the Quaternary period, the climatic belts 

 moved northwards m the glacial periods and southwards in the 

 Postglacial and mterglacial periods ; with them moved the forest, 

 savannah, and and steppe belts. A variation in temperature of 

 12 F. is involved, equivalent to a movement north or south of 

 800 miles. With the advance of the belts, a region may have 

 passed successively from desert into savannah to tropical rain- 

 foresl ; from aridity into relative fertility to revert on their 



