lxvi. 



If, however, the scratches and moraine debris be attributed 

 to the grounding of icebergs shed from the highlands of the 

 Southern Ocean, as conjectured by Mr. Scoular, then a con- 

 siderable amount of depression must have taken place, and to 

 account in this way for the deposition of the drift and for the 

 presence of the obsidian bombs scattered here and there 

 throughout the whole of the southern parts of this province, 

 the depression must have been great enough to submerge all of 

 the province below 1,000 feet or so in elevation. I need hardly 

 add that the known facts do not warrant such assumption. 



On the limestone surfaces of the Murray Basin and the 

 Bunda Plateau the loess is absent over very large areas, and 

 when present is of very shallow depths. In these areas it 

 could only originate from the insoluble residue of its lime- 

 stone rocks, which from their purity could only yield an 

 appreciable quantity by secular decay continued through 

 prolonged periods. In the oasis of the Bunda Plateau the 

 subaerial origin of the loess is incontestably shown, and it is 

 highly charged with land shells, vegetable debris, from top to 

 bottom. 



The loess in the South-east Plain is mainly preserved in the 

 pockets and depressions of the Miocene limestone, and in the 

 neighbourhood of the volcanic cones is covered up by ash beds. 

 It contains the remains of the large extinct Mammalia, and 

 the period of its formation must be coeval with that forming 

 the fertile plains of Adelaide, &c. At this time the caves in 

 the South-east must have been frequented by the extinct 

 mammals whose remains are embedded in their stalagmitic 

 floors. 



Retrospective Glance. — During the Pliocene period the land 

 was much elevated, probably into regions of perpetual snow. 

 The continent was then obviously vastly more extensive than 

 now. Tasmania and New Guinea would then be united to the 

 continent, as is required by the community of species of 

 certain plants and animals. It was during this time that the 

 large mammals roamed over the land, and the wide expanse of 

 country allowed of the development of its peculiar and ex- 

 tensive fauna. The climate moister, and the temperature of 

 lowlands more equable than now, and generally the conditions 

 were favourable to the growth of succulent herbage capable of 

 sustaining a large and varied mammalian fauna. The seas that 

 laved the shores had their inhabitants, but of them we have no 

 record, because the sites of their habitats are now far beneath 

 the waters. This period was brought to a close by the lowering 

 of the land — gradually, it may have been — and in consequence 

 of which its glaciers retreated and finally disappeared, and the 

 fertile tracts of the lowlands were submerged, and the produc- 



