DUNLOP ISLAND 83 



ancient Ross Barrier when it over-rode the whole of this region. Glacial valleys 

 prohably excavated by the same agent are to be seen at Cape Royds. Since the 

 retreat of the Ross Barrier the piedmont ice has pushed across the strait and 

 glaciated the gneissic granite in situ on the island in a direction from about 

 W. 35° S. to E. 35° N. 



The island is formed of shingle and redistributed glacial boulders and gravel. 

 The gravel is formed of small pebbles about half an inch in diameter, and the 

 boulders are mostly from 3 inches up to 18 inches in diametei'. 



Scale of PldP. 



lO 20 40 60 



80 



chains 



H 



^K-i;^^ Dunlop 

 m #x Island 



Gneissic Granice 

 striated from 

 W.35'S 



Dunlop Island 



Terraced glacial gravels 



resting on gneissic granite 



Longitudinal Scale 

 Vertical Scale 



Piedmont glacier ice 

 resting an gneissic granite 



olrait 



Dunlop Island. 



Uinaitudinal scale ?...,...■" ^ "" 



i/ertical Scale 



^0 



" chains^ 

 ' Feet 



Fig. 41 



One boulder of granite measured 6 by 5 by 3 feet. 



Its upper surface is strongly grooved in a south-east and north-west direction. 

 These main grooves ai-e crossed by another set coming from about W. 35° S., the direc- 

 tion of glaciation followed most recently by the piedmont ice subsequent to the retreat 

 of the Ross Barrier. The north-west to south-east grooves pointed straight to Hut 

 Point, 60 miles distant to the south-east, and it may be significant that a few fragments 

 of scoriaceous basalt and dense olivine basalt, both of which occur in situ at Hut Point, 

 were found here by our colleague, Dr. Mackay, among the boulders. We think it 

 may be concluded that the strait which separates Dunlop Island from the main- 



