SCIENTIFIC RESULTS 



119 



70° F.. will survive aj)j)r()xiniately 7 days, with considerable varia- 

 tion, e(iuivalent to a heialit i-eduction of about 10 feet per day. 



On April 11, 19l21, we measured a lar^e ber<j floating; in water 

 o4° F.. between Flemish Caj) and the Grand Bank, as '248 feet high. 

 (Smith. 192'2, Chart H.) When it Avas sighted again 10 days later 

 in SS'' F. water, it was 190 feet in height, and again 80 feet high on 

 May 9 in water of 44°. When last seen on May 12 in water 63° F., 

 it had shrunk to 60 feet. This indicates a rate of Avastage in altitude 

 of about 6 feet per day until the last few days, when the berg was 

 surrounded by warm tropical Avaters, and then it lost height at the 

 rate of 10 to 12 feet per day. Naturally, the bergs Avaste faster in 

 the summer time south of the (irand Bank than in any other region 

 of their occurrence; about six times faster than in the Arctic. In 

 June, 1926. a large berg, 382 feet in length, floating in the northern 

 edge of the Gulf Stream south of NeAvfoundland, completely melted 



A Major Calving of an Iceberg 



Figure 78.- — AVhile approaching this berg, 1 mile distaut, a part of the pinnacle on 

 the left broke off. The detached piece weighing hundreds of tons dropped into 

 the sea with a great roar. The white circle on the water around the berg is the 

 broken ice. and growlers. (Official photograph, international ice patrol.) 



aAvay in 36 hours. On the other hand, during the same year and 

 month there is the authentic report of a piece of ice sighted near 

 Bermuda. (U. S. Hydrographic Office, Hydrographic Bulletin No. 

 1944, December, 1926.) Icebergs on the northern part of the Grand 

 Bank sometimes survive as long as four to six Aveeks. And a large 

 l)erg stranded south of Belle Isle in April, 1924, did not completely 

 break up until August. These observations on the rate of wastage 

 agree Avith those of earlier investigators. Thus Drygalski (1895, 

 p. 420) measured some of the icebergs in Northeast Bay, Greenland, 

 (hiring the summer months and found that in a period of 7 days tAvo 

 of them decreased by 10 and by 13 feet, respectively, in height, Avhile 

 another in 6 Aveeks diminished from a height of 320 to 244 feet, a 

 loss of 20 per cent in altitude. Johnston (1913, p. 23) estimates that 

 bergs floating in Avater 50° F. or warmer suffer a 5 per cent reduction 

 of mass per day. 



120860—31—9 



