THE HEART OF THE ANTARCTIC 



Point, a few miles to the east-south-east of Granite Har- 

 bour, suggests the possibiHty that some of the dark sheets 

 of rock near the highest portions of the plateau may per- 

 haps be formed in part of kenyte. At the same time it is 

 possible that these kenyte boulders of Gneiss Point have 

 been drifted northwards from Ross Island amongst the 

 moraine material of the western branch of the former 

 gigantic Great Ice Barrier, when it occupied the whole of 

 McMurdo Sound. Dykes of dark rocks, resembling tin- 

 guaites, were not uncommon from Granite Harbour 

 northwards to near Geilde Inlet, south of the Drygalski 

 Glacier. We also observed dyke rocks full of small black 

 bright prismatic ciystals of hornblende. These appear 

 to be of the nature of hornblende lamprophyres. Small 

 pieces of scoriaceous volcanic rocks were found by us as 

 far north as Cape Irizar. These fragments may have 

 come from the mountains of the western plateau. 



Foundation Rocks 



The oldest rocks seen by us in the Antarctic belong to 

 the series already described by Ferrar and Prior, and 

 consist of banded gneiss, gneissic granite grano-diorite 

 and diorite rich in sphene. In some spots, as at Cape 

 Bernacchi, masses of very coarse white crystalline marble 

 are interspersed in the gneiss. 



These foundation rocks have their planes of foliation 

 sharply folded in places, as is the case at Depot Island, 

 the axis of folding there being approximately parallel to 

 the trend of the coast-line. Near the same spot huge 

 enclosures can be seen in the gnessic-granite. These are 

 partly greenish grey quartzites in masses ten to twenty 

 feet in diameter, partly large lumps of blackish green 

 coarsely crystalline hornblende rock, with much sphene 

 and a white mineral, apparently either saussuritised fel- 



