142 GLACIOLOGY 



The main rate of movement of the Barrier past Mimia Bluff has been ascertained 

 to be about 492 yards (450 metres) a year.* Reference to the cross-section of the 

 Ross Barrier, already given on Fig. 48, shows that for its total width of 450 

 statute miles (724 kilometres) the Ross Barrier has an average thickness of about 

 720 feet. This would give a superficies for the Ross Barrier vertical clift' face of (in 

 round numbers) about 1,710,000,000 square feet, while the movement at Minna 

 Bluff — probably a maximum area for speed— is 492 yards a year, the rate of move- 

 ment towards the eastern end of the Barrier must be extremely slow% perhaps almost 

 negligible, as Amundsen suggests. 



The rate of 492 yards a year is nearly 4 feet (r22 metres) per diem. It may 

 be assumed that as the eastern end of the Barrier is almost stationary, the mean 

 rate of advance is not more than about 2 feet a day, though it is quite possible, as 

 the Minna Bluff speed is probably a maximum, that it may not exceed about 1 foot 

 per day. At the 2 feet ^Jer diem rate of advance 3,420,000,000 cubic feet of ice 

 would be added to the sea- cliflP face of the Barrier daily. At the rate of advance of 

 1 foot •pQv day, 1,710,000,000 cubic feet would be the daily addition. As already 

 stated, on the assumptions made, the outlet glaciers from Skelton Inlet to the Beard- 

 more Glacier, inclusive, contribute in summer perhaps about 1,000,000,000 cubic 

 feet daily. 



To this must be added — 



(a) Ice contributed by outlet glaciers not examined by us, such as the ice of the 

 glaciers discovered by Amundsen, the Liv Glacier, the Axel Heiberg, and the Devil's 

 Glacier, and probably other glaciers between the Liv and Beardmore Glaciers, as 

 well as by glaciers between King Edward VII. Land and Carmen Land. 



[h) Numerous Alpine and Norwegian types as distinct from outlet glaciers, chiefly 

 on the east side, partly on the west side of the Ross Barrier. 



(c) Strips of old bay ice (sea ice) bridging over what would otherwise be lanes of 

 open sea water between the edges of the glacier ice jetties. 



{d) Drift snow and new-fallen snow deposited on the actual surface of the 

 Barrier. 



Obviously the December summer rate of movement of the outlet glaciers which 

 feed the Barrier cannot be maintained during the winter months, and so the 

 December rate of perhaps 1,000,000,000 cubic feet of ice daily may be distinctly 

 less in winter time. 



These figures are of course only roughly approximate, though based on the best 

 measurements available. Nevertheless they serve to show that the suggested 

 sources of nourishment of the Ross Barrier are reasonably competent to support 

 this magnificent floating piedmont, provided ablation over its surface did not 



* Fen-ar states {op. rit., p. 82) that Lieutenant Barne's measurements show that the Ross Barrier 

 near Minna Bluff moved 608 yards in 13i months. Our measurements extend over a period of 

 6^ years. 



