CAPE BARNE 109 



The height above sea-level is about 200 feet. The surface of the kenyte, ou 

 account of the great absorption of heat by day and the rapid cooling at night, 

 bringing about a quick disintegration of the rock through mechanical expansion and 

 contraction, has lost nearly all its former glacial striK through this frost weather- 

 ing. Only in one instance were well-preserved grooves observed on the surface 

 of a granite block, wedged into an angular hollow of the kenyte in such a 

 way that it still retained the direction of the grooves produced by the great ice 

 sheet when at its maximum. The light colour of the granite has led to its being 

 subjected to less exti'emes of temperature than the black kenyte, hence its surface 

 is much better preserved. The way in which this boulder has become embedded 

 in the kenyte and then hollowed out and grooved, is shown on the special map of 

 this area. The direction of the grooves is from S. 25° E. to N. 25° W., true. The 

 general trend of movement of the ice is also indicated by the bearing of the long 

 axis of the glacial lakes. Thus the long axis of Terrace Lake trends about N. 30° W., 

 that of Deep Lake and Sunk Lake trends about N. 15° W., Islet Lake about 

 N. 35° W. The long axis of the largest of these lakes. Blue Lake, runs about 

 N. 40° W., that of Clear Lake also N. 40^ W. The trend of the main wide shallow 

 valley, glacially excavated, that extends from Backdoor Bay to Horseshoe Bay, is 

 about N. 10° W. It may be said generally that the trend of the glaciation on the 

 whole appears to have been about between N. 10° W. and N.N.W. 



An interesting feature in the lake basins is Sunk Lake. As shown in the cross 

 section from C to B,* the surface of the ice of Sunk Lake is 18 feet below sea-level, 

 and the rock bottom of the lake probably 50 to 60 feet beloAv sea-level. This lake 

 is distant only 3 chains from the shore-line. While, as will appear later, there 

 is abundant evidence for a recent uj^lift of the land in this region, there is no 

 evidence of recent subsidence. The heavy downthrow fault Avhich bounds Ross Sea 

 on the west, with its disjjlacement of the order of 7000 to 8000 feet, appear to have 

 antedated the great glaciation. The fact that the bottom of this Sunk Lake rock 

 basin is below sea-level seems good evidence for the hollowing capacity of glacier ice. 

 Careful search was made by us over this intensely glaciated region of Cape Boyds 

 for any trace of true boulder clay, but we entirely failed to discover any. It must 

 be remembered that the Cape Boyds area was not by any means the lowest de- 

 pression glaciated in this region by the Great Ice Barrier. As shown by the 

 soundings of the Nimrod, at a point about 8i miles north by west from Cape Boyds, 

 and only 3 miles distant from the nearest land, McMurdo Sound is 459 fathoms 

 (2754 feet) deep, whereas the ice at Cape Boyds was 1000 feet thick a few miles to 

 the north, and to the west it was about 3750 feet thick. Under these circumstances 

 the bulk of the bottom moraine, possibly of the nature of boulder clay, would be 

 submerged under McMurdo Sound, and the morainic material stranded near Cape 



* See Plate VIII. in section on Meteorologj', and detailed map of the Cape Royds area, Plate 



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