PHYSICAL OOEANOGKAPHY OF THE GULF OF MAINE 



785 



circulation. This seems also to have been the case in 1912,' with absolute values 

 varying from 34.3 per mille in the extreme northeast, off Machias, Me. (10036), to 

 33.5 per miUe in the depression between Platts Bank and Cashes Ledge (station 

 10024). In 1915 the summer was likewise of this same type in the deeps of the gulf, 

 with 34 to 34.1 per mille in the eastern side and 33.5 per mille in the western at the 

 175-meter level; but in other summers the salinity of the deep strata is more nearly 

 uniform over the basin, as in 1913, when the values at 175 meters were 33.8 to 33.9 

 per mille in the western and eastern sides alilce.^ 



At depths greater than 200 meters the indraft through the Eastern Channel 

 does not have as free access to the two branches of the basin as at higher levels. 

 Consequently, their bottom waters have proved considerably less saline (34.5 per 



Portland 



Fia. 14S.— Salinity at a depth of 100 meters, August 5 to 20, 1913 



mille) than their union to the southeast, or than the Eastern Channel (35 per mille). 

 The bottoms of the deep bowl-like depressions in the offing of Cape Ann, in the one 

 side of the gulf, and off the mouth of the Bay of Fundy in the other, thus bear 

 much the same relationship to the still deeper bowl into which the Eastern Channel 

 opens as the sink off Gloucester and the other isolated sinks in the inner parts of 

 the gulf bear to its basin in general. 



At the 200-meter level (fig. 150) all the July and August determinations for the 

 western bowl (stations 10007, 10088, 10254, and 10307) have ranged between 33.7 

 per mille and 34.11 per mille, showing that very little annual variation is to be 

 expected there or regionally within its narrow confines. In the eastern bowl the 



^Ooly 5 stations were located in water as deep as 175 meters in 1912, and at only 3 of these can the 175-meter value be stated 

 within ±0.1 per mille. 



2 No observations were taken in the southeastern part of the area in August of 1912, 1913, or 1915. 



