PHYSICAL OCEANOGKAPHY OF THE GULF OF MAINE 



749 



liighly variable to that of more nearly constant salinity) close to the Isles of Shoals. 

 The zone within which river discharge rapidly increases the vertical range of salinity 

 in spring is no wider than this off Penobscot Bay, for the Grampus found the bottom 

 (32.43 per mille) only about 0.6 per raille more saline than the surface (31.8 per 

 mille) in 80 meters 3 miles off Matinicus Eock on May 12, 1915 (station 10276), 

 though the whole column was 0.2 to 0.6 per mille less saline then than it was on 

 the 9th of the following October (station 10329) or on January 1, 1921 (station 

 10496). 



Fig. 124.— Vertical distribution of salinity in the eastern side of the ba.sin of the Gulf of Maine on March 23, 1920 (A, 

 station 20086); May 6, 1915 (B, station 10270); May 29, 1919 (broken curve, ice patrol station 37); June 19, 1915 

 (C, station 10289); and August 12, 1913 (D, station 10093) 



The freshening effect of the Nova Scotian current affects the vertical distribu- 

 tion of salinity of the region influenced by it in precisely the same way as drainage 

 from the land, by producing a wide range between the surface and the deep strata. 

 The notable difference between graphs in the eastern side of the basin for March, 

 1920, and for May, 1915 and 1919, illustrate this (fig. 124) by a considerable fresh- 

 ening of the' whole stratum of water shoaler than 100 meters. ^^ 



•2 The actual data suggest a decrease of about 1 per mille at the surface and 0.7 per mille at 75 meters as normal for the period 

 during which the drift from the east is gaining head; but annual fluctuations of unknown amplitude complicate the picture. 



