34 ANNIVERSARY ADDRESS. 



flowers. How luxuriant, then, must have been the vegetation in 

 the Pleistocene period, when a great rainfall prevailed for 

 thousands of years. Can we not at once realize how, under 

 these favourable conditions, so many and gigantic animals existed 

 throughout the country ; why crocodiles abounded in the Darling 

 River country, near Brewarrina ; and also how both vegetation 

 and animals gradually died out as the wet climate changed to its 

 present arid condition — just as we now witness, in a small 

 degree, the awful devastation of pasturage and of animal life 

 over the same country when a season of drought comes on and 

 lasts for only one or two years. 



It has been said that Astronomy explains the principal cause 

 of these remarkable periodical changes of climate ; and it is 

 believed that our great rainfall period was contemporaneous with 

 the glacial period which has left such marked evidences in the 

 Northern Hemisphere ; during this period the Northern and 

 Southern Hemispheres being alternately glaciated. 



Its consideration is one of much importance in Natural History 

 investigations, for without it the origin of the living fauna and 

 flora, as well as of many of the physical features of Australia, 

 cannot be rightly understood. The present animals and plants 

 are the successors, direct descendants in some cases, of those 

 which lived under more favourable conditions of existence during 

 the Pleistocene period. This period, therefore, as I have already 

 said, possesses much scientific interest, and from it are avenues 

 open for research in Geology, Palaeontology, Botany, Zoology, 

 Physical Geography, Astronomy, etc., which should command 

 the special attention of Members of this Society. 



The phenomena of the Recent period are also of importance for 

 scientific observation, such as the wasting of land surfaces, 

 the widening and erosion of creeks and river channels, the 

 wearing away of coast frontages, and other effects of atmospheric 

 and marine denudation ; sand-drifts by wind, silting up of water 

 courses and harbours, and other modes of transit and deposition 

 of rock material ; the decomposition of rocks and the nature of 



