120 



MARIOX EXPEDITIOX TO DAVIS STRAIT AND BAFFIN BAY 



Assuming that an average run of large bergs for the Arctic lose 

 one-half their altitude before they reach the Grand Bank — i. e.. 250 

 feet to 125 feet — at a daily rate of 6 feet,"^ than an uninterrupted 

 journey of about five months is suggested. An average-size berg in 

 the Arctic regions is estimated to contain 50,000,000 cubic feet 

 (1,500,000 tons) of ice Avhile an average berg south of Newfound- 



Rate of Melting of an Iceberg 



FiGUKE 79. — This berg when first sighted on the east side of the 

 Grand Banli, April 11. 19-;i. was 250 feet high. Ten days later 

 it was 19U feet ; 18 days later. 80 feet ; and finally on May 12 it 

 was only 60 feet above the sea. The average loss of height per 

 day for icebergs around the Grand Bank is 6 feet ; and in the 

 Gulf Stream this accelerates to 10 feet per day. 



land has a volume of approximately 0,000,000 cubic feet (150.000' 

 tons), figures which upon comi)arison rei)resent a reduction of mass 

 from 8 to 1, Greenland to Newfoundland. These estimates of a 

 mass reduction of seven-eighths agree very well witli the height loss 

 of one-half. 



*i A rough approximation of reduction of daily altitude is 2 feet. BaflSn Bay : 4 feet, 

 Davis Strait ; 6 feet, Newfoundland and Grand Bank ; and 10 feet, south of Grand Bank. 



