PHYSICAL OOEANOGKAPHY OF THE GULF OF MAINE 



755 



In the year 1915 salinity was determined at 19 stations in June, sufficing to out- 

 line the regional and vertical distribution for the eastern side of the area and out 

 across the shelf south of Cape Sable; whde the FisJi Hawk stations for 1925 extend 

 the picture to Massachusetts Bay. 



The most instructive feature of the surface chart for June, 1915 (fig. 128), is its 

 demonstration that the drift of water of low saUnity into the gulf from the east had 

 slackened, if not entirely ceased, since mid May, the isohaline for 32 per mille having 

 shifted 50 miles or so eastward from the location it occupied six weeks earlier (fig. 

 120), the salinity of this side of the basin having increased from 31.78 per mille to 

 32.25 per mille during the interval. While the Nova Scotian drift may have extended 

 to the eastern parts of Georges Bank in May (p. 745), an abrupt transition along 



Fig. 128.— Surface salinity of the eastern and central parts of the Qulf of Maine, June, 1915 



the eastern side of the Eastern Channel in June, from low values over Browns Bank 

 (31.5 per mille) to higher ones farther west, shows that it had ceased to expand in 

 this direction by that time. 



The incorporation of river water, which is responsible for vernal freshening 

 of the coastal belt, was reflected in 1915 by an average increase of 0.2 to 0.5 per 

 mille in surface salinity along the northern margin of the gulf from May (fig. 120) to 

 June (fig. 128, values ranging from 31.8 to 32.2 per mille). 



Within the Bay of Fundy, where the effects of the freshets from the St. John 

 River are responsible for a very sudden freshening of the surface from April to May, 

 as described above (p. 743) , the recovery is correspondingly more rapid than in the 

 open gulf, where the influence of any one river is spread over a wider area. In 1917, 

 for example, the salinity of the surface water between Grand Manan and Nova 



