116 T. W. E. David— "Varve Shales" of Australia. 



A fragment of the middle Carboniferous plant Cardi- 

 opteris is preserved at the top of the specimen exhibited 

 and it is hoped that when these varves are examined in 

 detail they will throw some light on middle Carboniferous 

 chronology. 



2. Varve shales of late Proterozoic or Lower Cambrian Age. 



The specimens of laminated rock exhibited were 

 obtained by Mr. E. C. Andrews and Mr. W. H. Browne at 

 Campbell's Creek near Poolamacca, north of the Barrier 

 mines at Broken Hill, New South Wales. They belong to 

 the horizon of 'Tapley's Hill Shale,' ' so named from the 

 type locality near - Adelaide, South Australia. 4 These 

 shales immediately overlie the masses of tillite described 

 by Professor Howchin as aggregating some 1,000 feet in 

 thickness. There can be little doubt that they are 

 " varve" shales, and that the laminae indicate seasonal 

 deposition. One specimen shows marked contempora- 

 neous contortion. The paired bands have a maximum 

 thickness. of about one inch and their total thickness is 

 about 1,000 feet. This gives a minimum of 12,000 years 

 as the time needed for the accumulation of the Tapley 

 Hill Shales. 



4 Howchin, Walter, The geology of South Australia, pp. 344, 362. 



