154 MAKIOX EXPEDITION TO DAVIS STRAIT AND BAFFIN BAY 



winter, drifts south faster in s])rin«r tlian do the bergs, hence the 

 latter arrive as the fields and floes are disappearino;. 



Upon approachin*; the Tail of the Grand Bank the ber^js either 

 wheel abruptly to the eastward, to drift northward along the north- 

 ern edge of the (lulf Stream, or they follow around to the westward. 

 If the bergs ground on the southern part of the bank, as many do, 

 they usually disintegrate there, and thus do not menace navicra- 

 tion farther south."' Some bergs, however, which drift westward 

 around the Tail, continue northward beyond the forty-third parallel, 

 where they are usually caught in the large counterclockwise eddy 

 which characterizes the water mass of this region.'* (See fig. 101.) 

 Still other bergs of this groui? may be cari-ied directly north- 

 westward, where they eventually ground well in on the Grand 

 Bank, even as far as 120 miles from the Tail, and survive for sev^eral 

 weeks before finally disintegrating. Occasionally a berg is ev^en 

 carried as far west as longitude ^A' or T)')" W. in this way. Shortness 

 of drift, together with a slow rate of travel, probably reflecting the 

 weakness of the northern current, are the outstanding features of the 

 drifts of early April bergs. 



Bergs drifting southward toward the Tail attain maximum abun- 

 dance during May, reaching a normal total of 130 south of Xewfound- 

 land. At this, the height of the season, they tend to drift along paths 

 h and / (fig. 97). provided the cold current is normally tleveloped. 

 The prevailing drift is thence soutlnvesterly to a region bounded by 

 the forty-second and forty-third parallels and the fifty-first and fifty- 

 second meridians, in which vicinity most of the bergs of May swing 

 sharply to the eastward, paralleling the northern edge of the Gulf 

 Stream. As a modification of this type, the ice may set more to 

 the soutlnvard and even southwest of the Tail (see figs. 105 and 106), 

 but in most cases it does not drift deeply into the Gulf Stream before ij 

 being borne ofl' eastward, and finally northeast, where it rapidly 

 melts. However, in a year when arctic influences are weak, or the 

 Gulf Stream abnormally strong, bergs do not reach the Tail but are 

 deflected eastward along paths c/ or e. Figure 97. (See also figs 100, 

 101, 103, and 104.) 



June Avitnesses a decline from the season's maximum iceberg crop. 

 The nornuil number is 68 bergs south of Newfoundland. The first 

 week of this month may not show any apparent slacking in the 

 stream of bergs, but by the latter part of June, as a rule, the drift of 

 the ice past the Tail of the Grand Bank noticeably diminishes, due 

 to any one or all of the following causes, the relative inii)ortance of 

 each still remaining to be determined : 



{a) The encroachment of warm oceanic water northward in the 

 surface layers toward the Tail of the Grand Bank. 



(h) The Avestward encroachment of the inner side of the Gulf 

 Stream toward the eastern sloi)e of the Grand Bank. 



(c) The Avithdrawal of the pack ice along the coasts and shelves to 

 the northward allowing the bergs to work inshoi-e and strand. 

 . — I 



''^ During: the ice season of 1!»22 wo s;uv several bersjs float asain after several days 

 delay in on the southwest slope of the bank, su to resume their journev southward. 

 (Smith, 192:',, p. 58.) 



■"In l!»l.'l (see Smith, IOL'2. Cliart II) the lar^e elliptical track taken by an icebers off 

 the western slope of the (Jr.iml r.aiik i;ave the lirst iiikliiiu: that such phenomena pievalled 

 in ni(> current system. Hut several times since then i see Smith. 11)27. p. SC. .uid l!)27b, 

 l>. 70) the dynamic topourapbic maps of tbi^ sea surface have proved ■.■onclusively the 

 existence of such a cycb)iiic depressiou. 



