118 MARION EXPEDITION TO DAVIS STPiAIT 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 1'2 to 14 days during April. 



A Clcse-up View of an Iceberg at Sea 



Figure 77. — A close view showing the three processes of wast- 

 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 repiesents a reduction of height at the rate of 5 feet pel 

 day in April and feet per day in iNlay and June. An equal sized 

 berg farther south within the conhnes of the Gulf Stream, 05^ to 



