188 THE BUILDING OF EASTERN AUSTRALIA 



The first existed in early Eocene times, during which 

 a warm climate existed throughout Australia. 



The Cretaceous sea had vanished, all but a gulf extend- 

 ing over Western Victoria and Riverina. {Fig. 10.) The 

 Central Sea had become silted up or slightly elevated, 

 so that a desert or a series of salt lakes resulted. There 

 were no mountains in Australia, for all elevations had been 

 base levelled during the Cretaceous period of sedimentation. 

 In the waters, about Table Cape, Tasmania, the fora- 

 minifera exhibited tropical affinities, and resembled those 

 now found around Torres Straits. The plant life was 

 of a tropical or semi-tropical character, as shown by their 

 remains in the older leads, and so essentially similar a 

 flora existed throughout the eastern part of the continent 

 that it is safe to suppose that geographical barriers, such 

 as high mountains or deserts, were not in existence. 



Then followed the early Tertiary uplift which affected 

 the whole rim of the continent. The more central portions 

 of Australia participated only to a minor extent. 



A long period of stability then came, during whic) 

 the uplifted peneplain was dissected and worn down again 

 to the form of a peneplain. This stage was reached pro- 

 bably in the Miocene. 



Then followed an other great uplift, probably Pliocene, 

 and at the same time were erupted the Kewer Basalts. 



The period of the Newer Basalts was probably very 

 wet, and the Australian interior was experiencing a wet 

 climate at the same time, and during most of the Pleistocene 

 period as well. As evidence of the lacustrine state of the 

 interior during late Tertiary and Fost-Tertiary times, 

 one might quote the widespread existence of gypsum 

 deposits formed in former lakes, and the great extents of 

 Black Soil Plain, which were formed largely from volcanic 

 detritus, carried down by mightier streams than those 

 which hold sway to-day. 



Following the Pliocene uplift and the great basic 

 outpourings of lava, came a period of contracting, fractur- 

 ing and block-faulting of the surface strata of the earth's 

 crust in the newly uplifted regions. Numerous downthrows 

 (senkungsfeldter) occured as a result. The block-faulting 

 in the southern tablelands of N.S.W. has been ably de- 

 scribed by Sussmilch [11], a long list of probable faults 



