52 



AUSTRALIAN QUATERNARY CLIMATES AND MIGRATION 



He states that the lava-flows from Mt. Buninyong that covered 

 the lacustrine clays need not be of any great age. That the clays 

 are quite recent is evident from the fact that the Buninyong Bone 

 was a portion of the rib of Nototherium; the bones of Nototherium 

 are sometimes found under a scoria-cone flow but never under 

 the older flows of the lava-field or lava-plains. Mt. Buninyong is 

 a scoria-cone from which the lava Hart mentions flowed down a 

 valley that formerly emptied its drainage into the Murray but 

 was later reversed and became part of the drainage-system to the 

 Southern Ocean. The black, lacustrine clay was deposited in a 

 depression which was covered by the lava ; the age of the clay is 

 nearly that of the overlying scoria-cone flow. The black clay was 



\* Surface 



Bone 



i in 1 1 1 



-men 



Ifr 



Imple- 

 200 ft 



i . 1 1 1 . 1 1 1 . • 1 1 



rom 



surface 



Basalt 



143 feet 

 thick 



Lacustrine 

 black pyretic 

 clay. 



FIG. 6 

 Section in Great Buninyong Estate Mine. 



deposited during a period when the rainfall was great enough to 

 support a humus-forming vegetation. Such conditions prevailed 

 during the earlier part of the Postglacial and the last glacial 

 period. The yellow clay of Pejark Marsh is not present in the 

 Buninyong section, and the black lacustrine clay appears to have 

 been covered by the scoria-cone flow before the dry period of the 

 Postglacial Optimum. 



Lakes such as that in which such lacustrine deposits formed 

 have been common in the district but most of them have been 

 emptied by the breaching of their perimeters. Baragwanath 



