106 GLACIOLOGY 



The problem now presents itself as to how it is possible for a long, narrow, floating 

 mass of ice — if it is floating, its seaward portion being only from one-quarter to 

 half a mile wide — to resist the force of the blizzard winds and strong accompanying 

 currents which in summer time, after the breaking up of the ice, sweep down 

 McMurdo Sound. One would imagine that under these conditions Glacier Tongue 

 would quickly break off" at its seaward end, and float away as bergs. We find, on 

 the contrary, that in the interval of between four and five years which had elapsed 

 between the date of Captain Scott's expedition in the Discovery and that of our 

 visit, the length and breadth of the Tongue had been pretty uniformly maintained. 

 It is quite possible that here, as is assumed to be the case at the Drygalski Ice 

 Barrier Tongue, the Tongue has pushed out a bottom moraine, or submarine esker, 

 like a great railway embankment, and is sustained rigidly on this for at least one- 

 half, possibly for as much as three-quarters, of its length. 



It is still difficult to understand, even on this hypothesis, why the tip of the 

 Tongue does not snap off" and drift away. Many more soundings are needed on 

 both sides of the glacier, and particularly on its seaward extremity, before this 

 problem can be solved. 



Turk's Head. About 6 miles north-westward of Glacier Tongue is the Turk's 

 Head Glacier. The steep slopes above the Turk's Head Nunatak are heavily 

 glaciated, and the glacier is strongly crevassed. It seems that here, and in the 

 direction of Cape Barne farther north, the glaciation on the western slopes of 

 Erebus attains its maximum. The probable cause for this, as has already been 

 suggested, is to be found in the vast quantity of drift snow, which has swept 

 on to this part of Erebus from the surface of the Ross Barrier to the south. 

 Thus the gathering ground which supplies the ice for this glacier, for Glacier 

 Tongue, and for the Cape Barne Glacier, may not be merely restricted to the 

 western slopes of Erebus, but may be potentially a considerable surface of the 

 Ross Barrier. 



A huge ice cave more than 50 feet in height is a conspicuous feature in this 

 Turk's Head Glacier. It is situated just at the point where the glacier descends 

 from the rocky shore into the sea, and has doubtless been excavated by waves 

 impelled by blizzard winds, at a time when there was open water to the south of 

 the glacier. As shown in the accompanying photograph, the ice at this point is 

 heavily crevassed. 



At the foot of the glacier was a large iceberg, so much crevassed that its top 

 was a series of sharp pinnacles. There seems no reason to doubt that this berg had 

 been recently broken off" from the Turk's Head Glacier, and it is very possible that 

 two other bergs composed of glacier ice, seen stranded a little to the north of Turk's 

 Head, were derived from the same source. The ice in this glacier close to where it 

 leaves the land must be about 150 feet in thickness. 



The view on Fig. 2 of Plate XXIII. shows how completely swathed in ice 



