118 MARIOISr EXPEDITION TO DAVIS STRAIT AND BAFFIN BAY 



observed from hour to hour. A berg of average size, 70 to 90 feet in 

 height, in mixed waters south of the Grand Bank will survive as a 

 menace to navigation for a period of 12 to 14 days during April. 



A Clcse-up View of an iceberg at Sea 



Figure 77. — A flose view showing the tlnx-e proci-ssys of wa^t- 

 age — melting, erosion, and calving — of an iceberg at sea. The 

 warm ocean swell, as it ceaselessly pours across the ledge 

 of ice in the foreground, is the most potent factor in the 

 disintegration of icebergs off Newfoundland. (Photograph 

 by Lieut. Commander N. G. Ricketts.) 



May, and June, but will not survive longer than 10 to 12 days there- 

 after. This represents a reduction of height at the rate of 5 feet per 

 day in April and 6 feet per day in JSIay and June. An equal sized 

 bere farther south within the confines of the Gulf Stream. 65° to 



