president's address. 557 



light coloured and variegated siliceous rook (f. Tepper) resting 

 perhaps conformably on Ardrossan marble. 



Judging from Mr. Tepper's section their thicknesses are as 

 follows : — 



Ardrossan sandstone ... ... 15 feet 



Parara limestone ... ... ... 40 feet 



Siliceous rock ... ... ... 18 feet 



In the Mount Lofty Ranges is a vast thickness of rock, the 

 exact horizon of which has not yet been determined. Mr. R. 

 Ethridge, junr., informs me that he considers a portion of this at 

 any rate to be Cambrian. 



Mr. H. Y. L. Brown-''' describes these rocks as consisting of two 

 series, the lower composed of quartzites, sandstones, clay shales, 

 and conglomerates, the last-mentioned at Sturt's Creek, containing 

 pebbles of granite and quartzite, and the upper of crystalline 

 limestones, flaggy ripple-marked quartzites and sandstones, and 

 massive quartzite. The upper series may possibly be Lower 

 Silurian, though Mr. Brown does not mention any unconformability 

 between them. Near Parachillna and at the Blinman Mine, to the 

 South of Leigh's Creek, and about 260 miles northerly from 

 Adelaide, quartzites, claystones, conglomerates, dolomite, and 

 limestone have been described by Mr. Brown. f These rocks have 

 been strongly folded, the axes trending W.N.W. and E.S.E. 



Representatives of the oldest known fauna of Australia are met 

 with in the Cambrian rocks of Yorke's Peninsula above referred 

 to. They have been described by Professor Tate, Mr. H. Wood- 

 ward, Mr. R. Etheridge, Junr., and Mr. Howchin. The following 

 have been recorded by Professor Tate in his succinct account of 

 the Cambrian Fossils of South Australia. | The extreme interest 

 which attaches to this the oldest known fauna of Australia is my 

 excuse for quoting at length from this paper. 



* South Australia. Annual Report of the Government Geologist, Dee. 

 1st, 1882, to Dec. 31st, 1883, p. 10. 



t South Australia. Report on the gold-bearing area in the neighbour- 

 hood of Leigh's Creek. By authority. Adelaide, 1891, p. 1. 



X Trans. Roy. Soc. South Australia, 1892, pp. 183-189. 



