120 



toward themselves because of the physical impossibility of anything 

 chilling the already frigid water by more than 1° or 2°. 



Throughout the year, just below the upper 25 or 50 meters of water 

 throughout almost all the 74,000 square sea mile "melting area," the 

 next layers of water remain, in general, very cold. At many stations 

 38° and 37° F. water is found just below the 25-meter level, even 

 though the time may be June or July, and 50° to 55° F. water may be 

 encountered at the surface. 



Let us consider the conditions that prevailed in the upper portions 

 of the water column at station 1085. That station was taken at 42° 

 01' N., 49° 29' W., about 3 miles east of a large berg, on July 18, 1929. 

 The conditions there are listed below and are a bit more extreme than 

 the average, but still they are rather typical of the melting conditions 

 that surround nearly all the bergs that melt south of the forty-fourth 

 parallel during the last half of the ice-patrol season. 



It is evident from an inspection of the above figures that the berg 

 because of the increasing salinity wdth depth, woidd be forced to chill 

 the surface waters very much more than 21.8° F. in order to sink 

 them down to the 50-meter level. The inevitable freshening of the 

 waters while they are being chilled by the glacial ice w^ould make it 

 still harder for them to be sunk. 



Let us neglect the great differences of salinities and the freshening 

 effects and assume that the berg will chill the surface waters in 

 immediate contact with it 20° F. and sink them to some depth 

 located between the surface and 50 meters where they will find their 

 new hydrostatic level. It is easy to calculate the approximate 

 amount of water that can be chilled 20° F. by an individual berg of 

 130,000 short tons mass. Lieut. Commander Edward H. Smith 

 estimates this to be the size of the average berg about the Grand 

 Banks, so it can safely be taken as the average size of bergs in the 

 southern half of this area south of the forty-fourth parallel. 



If each pound of the ice can chill 80 pounds of water 1° F., a 

 260-million pound berg can chill approximately 1,040 million pounds 

 of water 20° F. At 62}^ pounds per cubic foot, the amount of water 

 chilled 20° F. would be 16,640,000 cubic feet. Suppose the berg 

 lasts out a full life-expectancy for surface water over 50° F. and 

 continues to melt for 10 days. It will then sink daily, on the average, 

 1,664,000 cubic feet of water chilled 20° F. 



