710 BULLETIN OF THE BUREAU OF FISHERIES 



The only important difference between the distribution of saUnity at the surface 

 of the gulf and at 40 meters for March is in the coast sector between Portland, Me., 

 and Penobscot Bay, where the freshening of the surface by river water (p. 704) does 

 not at first affect the salinity to as great a depth. 



The fact that moderately high salinities (34 per mille) lay closer in to the sea- 

 ward slope of Georges Bank at 40 meters depth than at the surface in February and 

 March (cf. fig. 91 with fig. 93) is also worth mention as evidence of some recent 

 expansion of the surface water offshore. 



100 METERS 



The regional differences in the rate at which the salinity of the gulf increases 

 with increasing depth (p. 706) result in a much wider contrast in salinity between the 

 eastern and western sides of the gulf in the mid depths (as represented by the 100- 

 meter level by March) than in the upper stratum (fig. 94). 



In the western and northwestern parts of the gulf, it is true, the mutual rela- 

 tionship of water fresher and Salter than 32 per mille is then made essentially the 

 same at 100 meters as at shoaler levels by the homogeneity of the superficial stratum 

 (p. 705) and by the fact that the slight increase with depth was nearly uniform from 

 station to station in that subdivision of the gulf. A somewhat higher salinity (32.92 

 per mille) near Cape Cod (station 20088) than that of the surrounding waters (32.5 

 to 32.6 per mille) is only an apparent exception to this generaUzation, reflecting some 

 local upwelling from the salter, warmer waters below, an explanation corroborated by 

 the fact that the 100-meter temperature was also slightly higher there than at the 

 neighboring stations (fig. 13). 



In the eastern side of the gulf, however, the curves for the several values (33 

 to 34 per mille) clearly outline a very definite and highly saline but narrow core 

 entering the gulf via the Eastern Channel, at the 100-meter level (hardly suggested 

 at the 40-meter level) , spreading northward along the eastern slope of the basin, to 

 turn westward across the mouth of the Bay of Fundy as far as the longitude of 

 Mount Desert. It is probable, also, that a smaller increment was entering the Bay 

 of Fundy, or had recently entered, because the vertical increase in salinity from the 

 40-meter level downward was somewhat more rapid at the mouth of the latter (32.7 

 per mUle at 100 meters at station 20079) than we have found it anywhere in the 

 western side of the gulf during March. It also seems certain that at the date of 

 observation (March 13 to 23) this saline tongue was continuous with the still salter 

 oceanic water via the eastern side of the Eastern Channel, witness a salinity of 33.78 

 per mille at 100 meters at the outermost station off Cape Sable (station 20077), 

 where the surface and 40-meter levels were by contrast notably low in saliaity 

 (p. 1000). On the other hand, values lower than 33 per mille at 100 meters on the 

 eastern peak of Georges Bank (station 20070) and along its southeast face (station 

 20068) suggest that water less saline than 33 per mille was then drifting out of the 

 gulf along the western slope of the channel, to pool off the southeast face of Georges 

 Bank and so to hold the oceanic water (>35 per mille) at least 60 miles out from the 

 latter. However, this pool of water of low salinity (and of low temperature) extended 

 only a few miles around the tip of the bank to the westward, with salinities higher than 

 34 per mUle washing its southern face. If 35-per miUe water did not actually touch 



