tered the area after the middle of the month but those already 

 there were continuing to approach the steamer lanes to the south- 

 eastward of the Grand Banks, more than south of the Tail of the 

 Banks. Both air searches and surface vessel scouting- were made 

 difficult because of the expanding area which might contain bergs 

 in positions of menace to trans- Atlantic traffic. A small berg, 

 reported on the :27th at 40'54' N., 40'26' W., represented the 

 farthest southeastward drift of ice during the 1946 season. As 

 the month was drawing to a close it was apparent that track C, 

 to which United States-European tralffc normally shifts on 1 July, 

 would not be clear of endangering bergs and growlers by that date. 

 Track B was therefore kept as the prescribed route for United 

 States-European traffic until the advancing season would free track 

 C of ice hazard. With the summer warming of the surface water 

 the surface isotherms became more difficult to interpret in terms 

 of currents. It was therefore of considerable immediate utility 

 that the Tampa was able to follow the drift of the then southeastern- 

 most known berg froin the 22d until it broke up on the 29th. It 

 is estimated that 88 bergs entered the area south of the 48th par- 

 allel during June. Their distribution is shown in figure 45. 



July 



As the month opened it was apparent that few, if any, more bergs 

 would get south of 48° N. It remained then to account for those 

 already in the area. By the 6th surface and aerial scouting had 

 established the absence of bergs in the area south of 45° N., and 

 west of 46° W. A number of reports were received during the 

 next few days of bergs and growlers between 43° and 45° W., from 

 the 43d parallel northward. Making a thorough search of this 

 area was a lengthy task because of the persistent poor visibility. 

 However, it was possible to keep a reasonably good surveillance 

 over the eastern edge of the Grand Banks from 45° N., to 46° 30' N. 

 By the 22d the eastern part of the area had been searched and 

 found free of ice. The surface patrol vessel then scouted along 

 track C to the Tail of the Banks and on the 24th United States- 

 European traffic was shifted to that track. The surface patrol 

 vessel then searched northward along the eastern edge of the 

 Grand Banks and as no ice was located the patrol was discontinued 

 for the 1946 season on 27 July. It is estimated that 7 bergs drifted 

 south of the 48th parallel during July. Figure 46 shows the dis- 

 tribution of bergs during July. 



Augusf, September, October 



No bergs are known to have drifted south of latitude 48° N., 

 during these months. 



129 



