CAMBRIAN 241 



Associated with these remains of the ArchwocyathiiKe is a very abundant 

 dendroid organism, which shows in dark arborescent radiating forms in the lighter 

 matrix of the limestone. Mr. R. Etheridge of the Australian Museum, Sydney, 

 W. S. Dun, Palaeontologist to the Geological Survey, Sydney, and Mr. Frederick 

 Chapman, Palaeontologist to the National Museum, Melbourne, all agree in referring 

 this organism to some kind of calcareous plant, such as Soleno2>ora. 



Mr. Chapman concludes that this plant may be compared with Confervites 

 2'>rimordialis of Bornemann, from Sardinia, also recorded by Von Toll from Siberia ; 

 Epiphyton jiahellatum (Bornemann), from Sardinia ; and Siphonema ( = GirvaneUa) 

 incrustans and S. areaceum (Bornemann), from Sardinia. Mr. Chapman considers 

 it most nearly allied to the Epiphyton, though he also admits that it has affinities 

 with Solenopora* 



On the assumption that the fragments of limestone with the breccia are of 

 Cambrian age, the question suggests itself, what is the age of the breccia as a 

 whole ? Obviously it must be Post-Cambrian. The breccia, as far as we are aware, 

 has not yet been discovered in situ, but as this discovery is to be made the special 

 quest of the British Antarctic Expedition of 1910-12, it is highly probable that 

 the breccia will now have been located in situ. It is possible that it is a basal 

 breccia at the base of the Beacon Sandstone formation. On the other hand. Sir 

 Ernest Shackleton was of opinion that the massive limestone in situ at Buckley 

 Island, at the head of the Beardmore Glacier, was actually interstratified in the 

 Beacon Sandstone formation. Mr. F. Wild was of the contrary opinion, and 

 considered that the limestone, though in altitude a little higher probably than the 

 Beacon Sandstone, was in reality dipping underneath it. The photograph of 

 Buckley Island shows a slight dip of the Beacon Sandstone formation down 

 the Beardmore Glacier Valley, but the angle of this is low, and it is doubtful 

 whether, without the intervention of a fault, the Beacon Sandstone can be con- 

 sidered to be stratigraphically above the limestone. This is a question which 

 no doubt has been definitely settled by the scientific members of the Britisli 

 Antarctic Expedition of 1910-13 under Captain Scott. In the section (Plate I. 

 Fig. 3, accompanying this Report) from the inland ice across the great horst and the 

 ice barrier to Mount Erebus, we have adopted the view that the limestone of Buckley 

 Island is identical with that which has supplied the fragments to the limestone 

 breccia, that Mount Darwin is therefore Cambrian, and that the breccia has been 

 derived from the waste of this limestone, and forms a basal bed under the Beacon 

 Sandstone. It may be noted that Ferrar describes {op. cit., p. 41) the occurrence 

 of thin limestones interstratified in the Beacon Sandstone, and a fragment of fine- 

 grained argillaceous limestone discovered by us at Dunlop Island is also probably 

 derived from this horizon. The latter showed traces of organisms resembling some 



* Professor Garwood has recently described Solenopm-a-\\ke organisms from the Carboniferous rocks 

 of Great Britain. 



