136 MARION AND GENERAL GREENE EXPEDITIONS 



a similar type of water. The increase in the difference between the 

 Coast Guard's data and the Michael Sars'' data, with proportional in- 

 crease in depth, on the other hand, testifies to the shoaling of the 

 Atlantic Current with approach toward its borders. 



VERTICAL DISTRIBUTION OF TEMPERATURE AND SALINITY 



The same foregoing stations, with the exception of those of the 

 Michael Sars, have been utilized to construct the vertical sections. 

 These temperature and salinity profiles correspond section for section 

 to the velocity profiles already discussed ( p. 133 ) . Labrador Current 

 of low salinity and temperature hugged the Atlantic slope of the 

 Grand Banks while adjacently offshore lay salty warm water of the 

 Atlantic Current. The draft of the Labrador Current as indicated 

 by the above sections agrees well with the average depth of 950 

 meters obtained from the velocity profiles. 



The presence of sub-Arctic intermediate water corresponding to 

 that defined by Wiist (1935) and found by Iselin (1936, p. 47), is 

 evident at depths of 400 to 600 meters as represented on the salinity 

 sections T and U (fig. 99). Reference to the corresponding velocity 

 profiles (fig. 95) establishes the motion of this water, with its prin- 

 cipal component, as northerly. It is our view that this is mixed 

 water formed by cabbeling along the boundaries of the Labrador 

 Current and the Atlantic Current (see p. 183). 



The relatively small area of cool water on the southwest edge 

 of the Grand Banks, as marked by the 3° and 4° isotherms (section 

 X, fig. 98), is corroborative evidence of the very small proportions 

 of sub-Arctic water which continue as far westward as this point 

 from the Tail along the continental slope. The northern border of 

 the Gulf Stream in the deep water between the Grand Banks and the 

 Nova Scotian Banks often lies as far north as latitude 43°-30' in the 

 vicinitv of the fifty-fourth meridian. (See Smith, 1923, 'Stations 

 178 aiid 209; also Bjerkan, 1919, stations 16, 17, 74, and 75.) A 

 cold, low-salinity discharge from the Laurentian Channel appar- 

 ently displaces the Gulf Stream southward in longitudes 56° and 57% 

 and thus accentuates a warm salient in longitudes 53° and 54°. This 

 characteristic northward encroachment of the Gulf Stream appears 

 to dam the westward flow of the Labrador Current. Small quanti- 

 ties of Labrador Current from around the Tail may, at times, escape 

 along the continental slo])e past the above barrier (Smith, 1924, 

 stations 353 and 354) and join other small tributaries such as the 

 occasional extensions of the Labrador Current across the shelf south- 

 west of Cape Race (Smith, 1924, p. 92) or a more pronounced and 

 constant tongue of cold water from the Laurentian Channel (Bjer- 

 kan, 1919, station 12). Such intermittent contributions prf)bably re- 

 sult in cooling and freshening the surface layers in the slope water 

 as they mix with the margin of the Gulf Stream system (see Iselin, 

 1936, fig. 57). No direct extension of tlie Labrador Current to the 

 coast of the United States has been emphasized by Bigelow (1927, 

 pp. 825-836). 



There is little evidence in the deepest temperature and salinity 

 observations in the Grand Banks sector (figs. 98 and 99) of the cold 

 water which was indicated on our Labrador Sea sections as draining 

 out along the American slope (p. 184). This movement has prob- 



