I.] GEOLOGICAL OBSERVATIONS 333 



The Gneissic Rocks. 



As the gneissic rocks occur at sea level at the foot of the 

 highest part of the Royal Society Range, and as they are also 

 found in the interior of the range below a sequence of rocks 12,000 

 feet thick, they may safely be regarded as forming the ancient 

 platform on which the central part of South Victoria Land is built. 



The foothills of the Royal Society Range appear to be mainly 

 composed of metamorphic limestone, which Mr. G. T. Prior tells 

 me probably belongs to the gneissic series. These limestones 

 form rounded hills which rise to heights of over 4,000 feet above 

 sea level and are quite isolated. Dr. Koettlitz and Dr. Wilson 

 both aided me in collecting from these hills, and Mr. Barne pro- 

 cured a specimen of schist from near latitude 80° S. 



On both sides of the Blue Glacier the rock shows important 

 structural planes which dip to the east at an angle of 70° while the 

 strike is north and south. The hills end sharply on the west in a 

 very straight and steep face, which is suggestive of a fault. The 

 limestone is almost pure white, and the calcite is in rather well- 

 formed rhombohedral crystals often an eighth of an inch across. 

 When weathered it becomes so crumbly that it was difficult to get 

 a hand specimen from the rounded surfaces that were exposed. 

 Basic dykes cut obliquely across the planes of division, but only 

 at one spot, where one of these dykes is twenty yards thick, was 

 thermal metamorphism evident. 



Cape Bernacchi and the low rounded hills to the west of it 

 appear to consist of gneissic rocks which are similar to the gneisses 

 forming the lowest part of the left bank of the Ferrar Glacier. At 

 the point where the ice of this glacier just begins to float in its 

 narrow ^ord-like channel there is an exposure of the limestone, 

 which dips to the north-east at an angle of about 70°. The New 

 Harbour Heights, as well as the north-western extremity of the 

 foothills, are composed of hornblende-gneiss. The rock at the 

 latter spot is dark, fine-grained, and very streaky ; the foliations 

 dip to the south-west at an angle of 60° — a fact of some importance 

 when we consider the dip of the rocks of New Harbour Heights, 

 which is to the north-east. 



At the foot of Cathedral Rocks, at a distance of forty miles 

 from the coast and over 2,000 feet above sea level, there is an 

 exposure of gneiss some 500 feet high and three miles long. 

 There is a very sharp dividing line between the gneiss and the 



