324 SECTIONAL TRANSACTIONS.- C. 



Prof. W. T. Gordon. — Some Limestone Erratics from the Beardmore Glacier. 



Among the glacially transported fragments collected on the Scott Antarctic 

 Expedition around Buckley Island — Beardmore Glacier — were several pieces of 

 limestone which were handed to me for examination, on the chance that they might 

 contain determinable fossil remains. While a few fossil forms have been obtained — 

 and these of zonal value — the limestones are interesting from other points of view. 

 Among them are two types of special significance, as they give evidence of the 

 chmatic conditions under which they were produced, namely, oolitic and conglomeratic 

 limestones. The fossils also reflect on the physical conditions under which they lived. 



As regards the age of these rocks we have satisfactory evidence, for the oolitic 

 type contained a specimen of Dokidocyathus — a Lower Cambrian organism — while 

 between the small pebbles of the limestone conglomerate a tuft of the alga Epipliyton 

 flabellatum has been obtained. In the pebbles of the conglomerate roUed fragments 

 of Archaocyathus, ooUtic and algal limestones are seen, and Thalamocijaihus and 

 Epiphyton flabellatum have both been recorded in these pebbles. In other words 

 the conglomerate was produced from the debris of oolitic, algal and archseocyathus- 

 limestones of Cambrian age. Further, subsequent to the formation of the ooUtic 

 limestone, the latter had been dolomitised to a marked degree, the process beginning, 

 as not infrequently happens, in the ooliths themselves. 



The conglomerate contained fragments of partially and completely dolomitised 

 oobte, so the process must have been proceeding during Cambrian times. Stated 

 otherwise, in Cambrian times, on an area now close to the South Pole, conditions 

 suited to the growth of algae and archseocyathinae must have supervened. 

 Further, the conditions favoured the formation of oolitic limestones, permitted of 

 the disruption of these limestones into conglomerates, and suited the dolomitisation 

 of the limestones. 



So far as arguments from other observations are available, such conditions could 

 only exist concurrently in shallow and rather warm water. That is, the conditions 

 were certainly not polar as we know them to-day. On the other hand, there is no 

 a priori reason to assume that polar temperatures in Cambrian times were much 

 different from those in corresponding latitudes to-day. These apparent contra- 

 dictions may be reconciled on the assumption that the rocks of Cambrian age at 

 present situated in South Polar regions were not accumulated in these latitudes, but 

 had moved into that location since Cambrian times. The alternative hypothesis, 

 that more genial chmatic conditions prevailed over such latitudes in these early 

 days, has no substantial foundation on observed facts. Of course, the notion i 

 of drifting continental masses is no new one ; but the accumulation of observations 

 from Arctic and Antarctic lands bearing on this problem may one day result in I 

 um^avellLng the history of the movement, and hence it appears worth while to draw J 

 attention to the most feasible explanation of the observations recorded above. 



Dr. A. K. Wells. — The Significance of the Accessory Minerals of Igneous] 

 Rocks. 



Afternoon. 

 Excursion to Stellenbosch. 



Thursday, July 25. 



Excursion to Chapman's Peak and Cape Point. 



In the evening the Section left for Laingsburg, arriving in the morning 

 of the following day. 



Friday, July 26. 



The day was spent in studying the glacial and tectonic features of the 

 Laingsburg district under the direction of Prof. A. Young. The Section 

 Jp-ft the same night for Kimberley. 



