SCIENTIFIC RESULTS 179 



total mass transport of the water, considering the entire breadth of 

 the slope, may remain more or less uniform. The speeding up in 

 one place along the slope, or retardation in another may cause the 

 current, as noted on the dynamic topographical maps, to divide 

 longitudinally into a series of bands or belts. In general the current 

 i-^ swift Avhere narrow and sluggish where wide; for example, in 

 July. 1928. as illustrated by the conditions met by the Marlon, expe- 

 (Htion described on i)age 149. (See fig. 95.) Off Nain, under the con- 

 ditions then existing, only the ice along the continental edge could 

 liave been receiving an appreciable southward set, while practically all 

 of the ice then floating off Belle Isle was making southward progress. 

 That an iceberg observed drifting southward at a moderate rate may 

 suddenly accelerate to double, or sometimes to treble its former 

 rate, is not evidence that the current throughout its entire lenjjfth 



Icebergs Caught in Pack ice 



Fkure 114. — An iceberg tsurrounded by pack ice on the northern part of the Grand 

 Bank, February. 1921. The majority of the flr.st bergs appearing s'outh of New- 

 foundland in early season, are sighted relatively wide off-shore, far to the east- 

 ward. An important factor of this seasonal variation in the course of the bergs 

 is the entangling pack ice which, driving before the westerly winds, exerts a 

 pronounced easterly component to the drift of the bergs. (Oflicial photograph, 

 international ice patrol.) 



has also increased but rather suggests a contraction in breadth along 

 the particular pathway that the ice is then following and this is an 

 important point as yet little appreciated in oceanography. 



The effect of pack ice on the .seasonal distribution of icebergs is 

 of two kinds: (a) AVhen driven before the wind it entangles the 

 bergs and tends to carry them along; or (b) it acts as a fender along 

 the shoreward side of the Labrador current during a critical period, 

 from Xoveinber to July, tending to prevent the icebergs from 

 I drifting toward the coast and grounding as they are borne south- 

 ward. This last assumption is corroborated by the fact that it is 

 at the beginning of the season, from February through March, 

 when the pack-ice belt is Avidest that the bergs are distributed 

 farthest to the east of the Grand Bank. 



If the velocity of the south-flowing current along the Labrador 

 and Xewfoundland continental edges, as suggested by the Marion 

 ?xpedition observations, of 1'2 to 1-1 miles per day be multiplied by 

 the number of days of the normal iceberg season around the Grand 



