DISCHARGE OF ICE FROM VICTORIA LAND Ul 



to estimate the quantity of ice which they annually discharge on to the western 

 side of the Ross Barrier and into the western side of Ross Sea. 



As regards the cross-section of the lower ends of the glaciers, the only data 

 as yet available — and they are very meagre — are for the Drygalski Ice Tongue. 

 This, as shown on our sections, has a mean thickness, in its central portion, of 

 about 2000 feet. It is possible that its thickness at its centre, at a point 

 20 miles east of the shore-line, may even approximate to 3000 feet, as the central 

 parts of this glacier are about 300 feet above sea-level. One may estimate that 

 these glaciers may average 2000 feet thick for an aggregate width of fully 100 

 miles. As has been previously stated, we saw evidence that the whole mass was 

 in movement from the fact that during a single night (December 17, 1908), in 

 about 10 to 12 hours, one of the vertical shear planes near its northern edge 

 moved about li feet. If this rate were maintained, it would mean a movement 

 of about 3 feet ("914 metre) per diem. 



If to this central mass of ice, 10 miles wide, the wedge-shaped portions of the 

 ice on either side, each 5 miles wide, be added, the total cross-section of this glacier, 

 where fanned out into the piedmont, would be about 15 miles (24 kilometres) by 

 2000 feet (610 metres). This would give a daily discharge of ice in the middle of 

 December, when the rate is probably approaching a maximum, of about 475 millions 

 of cubic feet per diem (13,486,264 cubic metres). If this average thickness of 2000 

 feet be maintained throughout the whole of the 100 miles in width of glaciers, from 

 the Beardmore to the E,eeves Glaciers inclusive, the total daily discharge of ice 

 would be less than 3166 millions of cubic feet, and even if one-third of this amount 

 be deducted to allow for thinning of the glaciers towards their sides, the amount 

 would still have the enormous total of, in round numbers, over 2,000,000,000 cubic 

 feet daily. At least one-half of this is probably annually added to the west side of 

 the Ross Barrier, the other half being discharged into the Ross Sea, along its western 

 shore. Thus annually from the Beardmore Glacier to Skelton Inlet, inclusive, the 

 Ross Barrier may receive daily, from the outlet glaciers alone, an amount of ice 

 equal to 1,000,000,000 cubic feet during the middle of December.* 



It may be interesting to compare this result with the known rate of movement 

 of the Ross Barrier, and the amount of ice that is there daily pushed forward to 

 the Barrier cliff face, where it breaks off to form bergs. 



* As regards other rates of movement of the glaciers of the Antarctic horst, Ferrar states (Nat. 

 Ant. Ex., 1901-4, G3ology, pp. 82-83), that at the south arm of the Ferrar Glacier the rate of 

 movement is probably less than 6 feet (1828'77 millimetres) a month, while the Blue Glacier moves 

 less than 4 feet a year. Both these glaciers are exceptionally stagnant, and are not a fair criterion 

 of the rate of movement of the great glaciers like the Beardmore, the Drygalski, the Reeves, &c. , which 

 shear and ridge the sea ice or Barrier ice, and push the whole Ross BaiTier in places some distance 

 away from the land. This supposition has quite recently been confirmed by the observations of 

 Griffith Taylor and Debenham of Scott's last expedition, that from the middle of December to about 

 the middle of January (1911-1912) the Mackay Glacier moved at the rate of about a yard a day. 



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