242 STRATIGRAPHY 



kind of fossil seed, like CarpoUthes, but the specimen was imperfectly preserved. 

 These limestones interstratified in the Beacon Sandstone appear to be distinct from 

 the dolomitic limestone of Buckley Island. 



It will have been noted already that limestoDe occurs on a grand scale in the 

 so-called Algonkian rocks, between Cape Bernacchi and the Koettlitz Glacier. It 

 is still possible that these massive graphitic saccharoidal marbles may not be 

 Algonkian, but may represent locally metamorphosed limestones belonging to the 

 Cambrian. The limestone in situ at Buckley Island is described by Professor Skeats 

 as in part being distinctly dolomitic, the other is not dolomitic. Professor Skeats 

 states that " obscure traces of fossils, including ArcJueocyathince, can be seen." 

 If this determination by Professor Skeats is quite \mque.stionable, it will at once 

 settle the problem as to the age of the Buckley Island limestone, for the limestone 

 there is actually in situ, in masses many hundreds of feet in thickness, and on 

 this determination it is obviously of Cambrian age. 



The Buckley Island limestone is traversed by curious dark greenish streaky 

 material. Profe.ssor Skeats considers that these probably represent a finely-divided 

 tuff " from a rather alkaline intermediate rock, such as a porphyrite or somewhat 

 basic trachyte on the one hand, and fine-grained micaceous detrital material on 

 the other." 



Amongst the erratics at Cape Royds some specimens were obtained of a well- 

 marked sillcified oolite. This very closely resembles some of the silicified oolites 

 in the Lower Cambrian rocks of South Australia, as near Hallett's Cove on St. 

 Vincent's Gulf and near Crystalbrook north of the head of Spencer's Gulf. Dr. G. 

 J. Hinde, F.R.S., compares these Antarctic silicified oolites with the Durness limestone 

 of Scotland. Under the microscope the grains show much radiating black carbon- 

 aceous material, which in places appears to have an obscure netted structure, hence 

 it was thought by one of the authors (T. W. E. D.) that it might represent an older 

 radiolarian rock. It is, however, very unusual for radiolarian shells to be preserved 

 in a rock that was originally a limestone. It is probable that as the Beardmore 

 Glacier Cambrian (?) limestones show a tendency to oolitic structure that these 

 silicified oolites are also derived from the same formation. 



Small erratics of limestone were foimd on the summit of Mount Hope at 2700 

 feet above sea-level, also pieces of a red limestone were obtained from the marginal 

 moraines on the western side of the Beardmore Glacier. It appeared to the 

 members of the Northern Party that there was limestone underlying the sandstones 

 which form a flat-topped capping to Mount Nansen. Small pieces of limestone were 

 obtained by that party from the old moraines to the south-east of Backdoor Passage, 

 southerly from Mount Larsen. It was not possible to determine whether these 

 limestones were below the Beacon Sandstone or interstratified with it. As far as 

 could be observed by inspection with a good field-glass the limestones were below 

 the sandstone. In this case they too may be of Cambrian age. Professor Skeats 



