84- GLACIOLOGY 



land was probably formed by the Ross Barrier. The coarse and fine gravels form- 

 ing the greater part of the island have probably been formed from glacial material 

 redistributed in sea water subsequent to the retreat of the barrier, and during a 

 submergence of 100 feet or upwards. At some time during this submergence the 

 gravel and boulder bank must have been over-ridden by the glacier ice of the 

 piedmont, and the large granite boulder firmly imbedded in the bank became cross- 

 striated. Then the piedmont ice retreated, and during re-emergence tidal scour has 

 separated the large gravel bank from the mainland, and has terraced the side 

 nearest the strait. 



To the south of Dunlop Island the piedmont ice is very extensively developed, 

 covering a large area inland to at least as far south as New Harbour. The general 

 appearance of this part of the coast is shown in a photograph by the Discovery 

 Expedition (National Antarctic Expedition, 1901-4, Album of Photographs and 

 Sketches, Plate XXXIII. Fig. 3, photo by L. C. Bernacchi). 



To the north of Marble Point we observed at least three low outcrops of granite 

 peeping out from beneath the piedmont. The piedmont therefore is still resting on 

 a coastal platform formed largely of rock. (Marble Point Is formed of calc-schist 

 and contorted mica-schist intruded by epidotic granite and aplite.) 



At Cape Bernacchi,* a few hundred yards to the south-west of the rocky point, 

 the shore is strongly terraced. 



The following section was then measured there by the Northern Party : — 



Mounds of angular rock Fragments, 

 I inch to 2 inches in diameter. 

 WO Ff terrace. 



40 F^ terrace 



Bottom moraine ? 

 20 ff terrace. 



\ \ [ TT^-r^-T-rrV-^^-^g ^->y .^ ^. J^lt^ 20 ff terrace 



Crystalline graphitic marbles . tourmaline, schist 

 and garnebiferous intrusive aplite. 



Fig. 42. SECTION SHOWING TERRACES AT CAPE BERNACCHI 

 The total length of the section is about 300 yards 



The lower terrace is composed of heavily glaciated pebbles and boulders, with 

 occasional erratics up to 5 feet in diameter. This appears to have been pushed 

 along under an ice sheet. 



The middle terrace is formed of Pre-Cambrian or possibly Cambrian crystalline 



* Cape Bernacchi is formed of coarsely crystalline saccharoidal marble with graphite flakes, 

 and also of schorlaceous schist. Both are strongly intruded by whitish granites. A good deal of 

 epidote has been produced along the planes of contact. 



