54 MARION EXPEDITIOX TO DAVIS STEAIT AXD BAFFUST BAY 



Hemisphere. In heavy ice years the pack lengthens out in long strips 

 (see fig. 5, p. 16) , and chains paralleling the edge of the bank, i. e., the 

 direction and flow of the current, as far south as the " Tail " on the 

 forty-third parallel. The farther southward the pack drifts the 

 more open it becomes and likewise the shorter time it lasts. South of 

 the forty-fourth parallel it is ver}' patchy and dismembered, surviv- 

 ing only a day or two. The latter part of March and the first of 

 April witness the deepest southern invasions.*" 



Scattered floes from the ice tongues are continually being broken 

 away by the prevailing westerly gales and driven across the continen- 

 tal edge into deep water, where the ocean swell and warm surround- 

 ings rapidly melt them away. A ship may report sighting patches of 

 pack in the morning, while another vessel passing the locality in the 

 afternoon may see no signs of it at all. It is a well-established fact 

 that pack ice rarely, if ever, extends westward around the Tail of the 

 Grand Bank. Although the cold current might tend to carry the 

 ice in such a direction the strong westerly winds prevailing at this 

 time of the year are dominant. A floe of pack ice was reported to the 

 ice patrol in March, 1924, as 120 miles southeast of the Tail of the 

 Grand Bank. 



The fields on the Grand Bank reach a maximum during April, 

 after which they recede, and by the latter part of the month or the 

 first of May extend no farther south than the northeastern part of 

 the Grand Bank. Under favorable conditions small fields of pack 

 may be sighted occasionally along the northern slopes of the Grand 

 Bank throughout May, but finally summer temperatures cause its 

 complete disappearance. The distribution of pack ice tends to follow 

 the primary circulation of the water, which over the Newfoundland 

 Banks progresses as a number of vortices, one spilling over into the 

 other. The winds ahvays exert a great effect, tending to mask that 

 of the currents. A characteristic embayment in the pack ice on 

 the Grand Bank is nearly always to be observed over the southwest- 

 ern slope, as shown on Figure 27, page 53, where unmistakably 

 warmer water floods in from off-shore. 



Although in the open Atlantic the pack tends to scatter and 

 many floes to drift aAvay from the main fields, the ice, nevertheless, 

 retains considerable strength and is still an imposing spectacle. On 

 the Grand Bank, even as far south as the forty-fifth parallel, ships 

 may easily become imprisoned, with no water from the masthead as 

 far as the eje can see. 



If we examine a few of the glacons in more detail, we find that 

 all exhibit a more or less tabular shape, with some of the older pieces 

 hummocked in round uneven contours. The glacons on the outer 

 edge of the pack, and scattered here and there in the open water, 

 show evidences of the greatest deteriorations. INIelting, however, of 

 all the ice progresses much faster at the water line than above or 

 below, resulting in characteristic tabular and hourglass shapes. The 

 thinner, smaller portion is always uppermost, not only on account 

 of equilibrium but also because the portion exposed to the air and 

 to the sun in the cold water of spring melts faster than the part 

 below water. The outward sloping form of the submerged under- 



*" According to the Deutsche Seewarte the most southerly penetration of pack ice was 

 in April. 1887. May, 1885, and June, 1882 and 1883, when it was sighted on the fortieth 

 parallel near longitude 49°. 



