136 



for small bands on the bottom and at the 25-meter (14-fathom) depth 

 in the gulley, and on the slope at the Tail. This change points to a 

 very active state of circulation prevaihng over the Grand Bank's 

 column. The increasing influence of warm fresh water supply to 

 the surface layers is now clearly noted over the entire southern half 

 of the Grand Bank and also northward into the area usually occu- 

 pied by the western branch of the Labrador Current. This appeared 

 to accumulate c[uite consistently over the central part of the Bank 

 where, being lighter than the surrounding water, it spread out on 

 all sides in the surface layers. The reason why, and the manner in 

 which, warm fresh water spreads out over the central ])art of the 

 Grand Bank may be explained by the well known expansion of low 

 salinity water seaward from land areas, a general condition which 

 is functioning throughout the year but attains a maximum during 

 summer. 



PROFILE NO. 15— STATIONS 345-350. 



*rhe section runs from in on the Tail of the Bank southward into 

 the Atlantic. The stations were taken June 27. 



Salinity. — Water less sahne than 347oo extended 80 miles out from 

 the slope on tlie surface. On the other hand, the outermost station 

 cut the inner edge of the Gulf Stream, which intruded noi'thward as 

 a tliin shelf at the 5()-meter level, as evidenced by the high salinilv 

 of 35.32«/o„. 



Temperafurf. — The section cuts ])ands of water colder than 0° 

 along the continental edge and in on the Bank at 50 and 200 meters 

 (29-109 fathoms), and shows the influence of these bands for (iO miles 

 offshore as a cool shelf, outlined by the 2.0° isotherm, with its axis 

 about the 100-meter (55-fathom) level. At the outer station the first 

 sign of the Gulf Stream was found in the surface and the r25-meter (68- 

 fathom) readings of 10° and 12°, which further corroborates the 

 evidence of sahnity. 



Attention was called in profile No. G to the depth of penetration 

 of the sun's heat in the water lying over the slope at the Tail. Since 

 this water lias been sliown to have a constant sahnity and tempera- 

 ture, viz, 3:V7„o to 34 7oo «rid less than 0° (Labrador Current) through- 

 out the ice season, it follows that any warming must liave been caused 

 by the sun. The following data are taken from ])rofiles Nos. 6, 10 

 13, and 15: 



Date. 



Surface 

 tempera- 

 ture. 



Depth of penetration of 

 2° isotherm. 



May 4. 

 May 31. 

 June 14. 

 June 27. 



2 I 10 meters (5 fathoms). 



4 j 30 meters (16 fathoms). 



»i 30 meters (10 fathoms). 



8 ' 2.'i meters (14 fathoms). 



