76 



contours, does not travel in simple streani flow, but is influenced 

 by the many varied factors which establish oceanic circulation, 

 resulting in a complexit}- of motion which can be represented in a 

 general way only. Local temporary movements are ever enlarging 

 or contracting in a maze of eddy-like and tongue-shaped formations/ 

 one of which undoubtedly caused the extraordinary easterly drift 

 of the aforementioned berg. For this reason, and contrary to pop- 

 ular conception, a berg drifting oxcoptionally far to the south does 

 not necessarily mean an unusual invasion by a cold current from the 

 north. A certain momentum imparted to the berg, sufficient to 

 carry it into the region of warm water, is all that is required to orig- 

 inate an extrasoutherly or extraeasterly berg drift. Provided one 

 of the varied temporary local movements of a certain water mass is 

 in progress, the berg will be borne along with it. These continual 

 interdigitations of water masses in the open ocean set up currents 

 which are termed "local." This should not mislead the uninitiated, 

 since the magnitudes involved may cause these eddies and tongues 

 to extend 200 or 300 miles. Consequently any attempt to chart 

 the surface plane of offshore oceanic circulation can be a figurative 

 representation only. 



From April 1 to 15 there were 24 bergs south of the 45th parallel, 

 and from April 15 to 30, 33 south of the 4Sth parallel and 10 south 

 of the 45th parallel. The positions of these bergs are shown on 

 cliarts '"H" and "I.'' On the 16th a berg was observed in hit. 42° 

 42', long. 50° 14'. (See chart "B," berg 14.) None of the bergs 

 that arrived at the Tail of the Bank during April exhibited any 

 tendency to drift to the southward; on the contrary, after passing 

 the Tail they were set in on the southwest slope of the Bank. The 

 drift of berg 14 (chart ''B") is an example of this, the cause of which 

 may be disclosed when we study the subsurface records for the season. 

 The force which caused this berg to change the direction of its drift 

 so abruptly on April 16 must have been of great magnitude, since 

 the velocity of the current which bore it down the east side of the 

 Grand Bank, April 11 to 14, was 1.2 knots per hour. 



This is the greatest strength ever observed for the Labrador Cur- 

 rent in this vicinity, and it is stated with some confidence, because 

 good atmospheric conditions permitted excellent astronomical ob- 

 .servations. The latter half of the month was foggy and necessarily 

 the patrol ship was handicapped in locating bergs. A "light-up" 

 on the last two days of the month disclosed a small berg (berg 15, 

 chart ''B"), subsequent observations of which showed it to drift in 

 on the southwest .slope of the Bank. Therefore, it is fair to assume 



> UollaQd-Haosen and Naasen: "Temperature Variations In the North Atlantic Ocean and Atmos- 

 phere." Smithsonian Miscellaneous Collections, Vol. 70, No. 4, p. 11, 1920. 



