. 140 



Sometime prior to March 31 warm, saline water, a dilation of the 

 northern side of the Gulf Stream, had shouldered northwestward 

 up the submarine valley which indents the continental slope in lat. 

 43° 40', long. 47° 15'. This invasive swerve tended to work inshore, 

 and to deflect a large proportion of the south — flowing water masses 

 offshore to the eastward. Whether this movement was sufficient 

 to explain the corresponding offshore drift of the icebergs at this 

 time, it is difficult to say. Such drifts, on the other hand, which 

 are characteristic of the early season (February and March), have 

 been attributed to the field ice farther north, which may act to fend 

 the bergs offshore. 



The encroachment of the warm saline water shoreward in the 

 topographical depression east of the Grand Bank develops chiefly 

 in the winter and early spring, when the Gulf Stream is more active 

 in this region than at other times. Several factors are involved, 

 which include tlie attractive force existing between two bodies of 

 water of extremely opposite character, caused by the so-called 

 ' ' cabbeling " along the boundary of their meeting.- Another probable 

 factor centers around the elevation in the ocean floor, which is a 

 southeastward continuation of the Tail of the Bank. The move- 

 ment of the water masses eastward, over and around tliis rise, com- 

 bined with the frictional arresting of opposite currents which takes 

 place along the zone of their mixture, ail enter into the mutual 

 interaction between these two waters of contrasting physical character 

 in this region during the late winter and early spring. 



Early in April the offshore movement of the l)ergs ceasetl and they 

 began to follow courses more or less parallel to the eastern edge of 

 the Bank. Another vertical section of these waters made the latter 

 part of April also indicates a slacking of the warm-water invasion 

 and a decreased tendency toward an offshore movem<'nt of tlie south- 

 flowing masses. 



Conditions around the Tail tlic middle of April are shown in a 

 sketch of the horizontal plane (30 meters (33 fathoms) below the 

 surface. The cold current was flowing southward at a record break- 

 ing velocity of 1.2 knots per hour, just north of the Tail (p. 74), 



'The reader is referred to Prof. Kniil Witlo's dear and simple treat nicni of ttn" siilijeit in the OeoRr. 

 An/.eiger, October, 1910: 



"When, on the boundary of an ocean current, warm water of high salinity is hroupht into contact with 

 Colder water of less saline character, hut having approximately the same specific gravity, then the resulting 

 mixture will, as may easily be proved by the Knudsen tables, be of greater density than either of its com- 

 ponent parts. It will eonsequently sink down, giving rise to the jjeculiar phenomenon known xs eabbeling. 



"()l>viously, this tendency in the water will likewise produce horizontal cunents; as the mived water 

 sinks down surface water must How in from cither side to take its i)lace. Hy way of example, we may 

 take the waters in the vicinity of the Newfoundhind Hank, where the (iulf Stream encounter.s the cold 

 current llowing down from thci Oreenland seas. Throughout the wide extent of the boundary surface 

 between these two mixed water is constantly being formed!, sinking down, and thus drawing in a continual 

 further supply of surface water from either side." 



It is this perpetual sinking of the water, of course, which renders the oceanic boundary line here so 

 vertical. 



