55 



horizontal and vertical scales should not be lost sight of. In section 

 E the left-hand vertical stability maximum is clearly correlated with 

 an eastward-intruding salinity minimum. The stability maximum 

 nearer the surface and on the right-hand side of the section might be 

 construed as corresponding with either an eastward-intruding salinity 

 minimum or a westward-intruding salinity maximum. The latter 

 construction is correct in the author's opinion. Section F shows an 

 undoubted correspondence between the right-hand stabiUty maxi- 

 mum and a southward-intruding salinity minimum. The left-hand 

 stability maximum probably corresponds with the depression of the 

 isohalines near the slope similar to the case of section D. The middle 

 stability maximum is the only one of those investigated which is not 

 apparently related to an intruding tongue of maximum or minimum 

 salinity and tliis may be because at tliis point in section F the major 

 direction of flow is nearly parallel to the section and therefore the 

 salinity section cannot portray a lateral intrusion. 



The sections shown in figures 55, 56, and 57 indicate that along 

 the borders of the Labrador Current and Atlantic Current, where 

 those borders are abrupt, lateral mixing taldng place at levels where 

 the vertical stability is a maximum, is characterized by an intrusion 

 of water from the parent current into the adjacent border Mater. 

 Where the border transition is not so abrupt, and where the border 

 water is present in considerable volume, the lateral mixing is char- 

 acterized by intrusion of border water toward the parent current. 

 Although further investigation will be necessary before it is known 

 how far the above statements can be accepted as generalities, the 

 implications are that we have here a possible mechanism for transfer- 

 ring across major ocean currents not only physical characteristics 

 but nutrient salts and pelagic flora and fauna having no inherent 

 power of locomotion. (See also A. C. Redfield, Nature, vol. 138, 

 p. 1013, Dec. 12, 1936.) 



Attention is called to the fact that in all of the sections investi- 

 gated the axes of maximum lateral mixing, as indicated by the axes of 

 maximum or minimum salinity, are slightly below the corresponding 

 axes of maximum vertical stability. It is as if the axis of maximum 

 vertical stability acted as a protecting layer from disturbances from 

 above and thus permitted lateral mixing to reach a maximum immedi- 

 ately below it. 



1936 POST SEASON CRUISE 



As has been mentioned, the post-season cruise in 1936 consisted of 

 a complete section from South Wolf Island, Labrador, to Cape Fare- 

 well, Greenland, and a shorter section ruiming in to the mouth of 

 Arsuk Fjord outside of I^dgtut, Greenland. The South Wolf Island — 

 Cape Farewell section has been occupied previously in 1934 and 

 1935 and approximated in 1928, 1931, and 1933. It is considered 



