259 



tween the creek and the hills, and it is improbable that the 

 present excavations have revealed the full extent of the lake 

 deposits. A fine clay occiipies the lower undulations border- 

 ing the creek over extensive areas, and this has been placed 

 under contribution for construction of the dams. This de- 

 posit probably marks the occurrence of the shallower water 

 around the margins of the lake, or the area that was sub- 

 jected to alternating conditions of lake and dry land, de- 

 termined by the variations in the rainfall. 



The waters of the lake do not seem to have been richly 

 furnished with life, or otherwise the evidences have been 

 lost. The disappearance of the remains of aquatic plants 

 can be easily understood. Chora, on account of its habit of 

 secreting carbonate of lime, is more likely to be preserved 

 than many others, and has left considerable deposits, but 

 the carbonaceous matter has been largely removed from, its 

 beds. Liimps of calcified stems of reeds can be seen in many 

 places, and a dark-coloured carbonaceous clay sometimes 

 occurs. The porous nature of the deposit may account for 

 the rarity of fresh-water shells. These have left, in most 

 cases, only a few white patches of limey material difficult 

 of determination. Bones of marsupials are not uncommon, 

 and these also, for the most part, are very friable. The 

 most important find was made by Mr. Bradley near the base 

 of the thick clay-bed marked e in fig. 1. These bones were 

 submitted to Professor Stirling, M.D., F.R.S., who has 

 kindly given the following determinations: — Macj'opn^ (kan- 

 garoo), PJ/a-'^rnJomj/s (wombat), and Bettoiigia (kangaroo rat), 

 all belonging apparently to living species. 



The facts now placed before you stand related to recent 

 geological changes in South Australia, involving wider data 

 which the author hopes at an early date to discuss. 



Postscript. — Since the above paper was read I have 

 made a second visit to Pekina Creek to investigate further 

 discoveries by Mr. Bradley. The previous observations were 

 limited to a long and narrow lacustrine area situated above 

 the irrigation weir, btit Mr. Bradley has been fortunate in 

 detecting the occurrence of further lacustrine deposits a mile 

 lower down the creek, at the back of the township of Oi'ro- 

 roo. The position of the find is on a level with the ancient 

 river flats, which widen out towards the plain, situated about 

 10 chains from the creek and 50 ft. above its present level. 

 A small knoll is capped by a calcareous deposit, which breaks 

 up into fragments, up to 6 in. in thickness, and consists 

 alm.ost entirely of the stems of Chara in a more or less mat- 

 ted condition. The beds of Cticnri in the upper portions of 

 i2 



