PHYSICAL OCEANOGRAPHY OF THE GULF OF MAINE 
773 
the upper stratum than at greater depths, with most of our stations showing a 
vertical range of 0.6 to 1 per mille between the surface and the 40 to 50 meter level 
(fig. 139). Eastward from Penobscot Bay we have found a more uniform gradient 
of salinity from the surface downward, as illustrated by stations near Mount 
Desert Island (fig. 107). 
Throughout the sector between Cape Cod and Mount Desert the difference in 
salinity between the surface and the 40 to 50 meter level is everywhere considerable 
in summer (though less than in spring, p. 728) — perhaps nowhere less than 0.3 per 
Meter 0 
20 
40 
60 
80 
100 
120 
140 
160 
180 
200 
220 
240 
260 
280 
300 
Fig. 138. — Vertical distribution of salinity in the western side of the basin, in the offing of Cape 
Ann, in July and August of different years. ©, August G, 1913 (station 10088); ©. August 22, 
1914 (station 10254); A, August 23, 1914 (station 10256); X, August 31, 1915 (station 10307). The 
broken curve marks the approximate limits to annual variation 
mille in July or August, with a maximum vertical range of about 1 per mille in the 
Massachusetts Bay region within these depth limits. 
Passing eastward from Mount Desert toward the Bay of Fundy, the vertical 
range of salinity is progressively narrower and narrower, corresponding to the more 
and more active tidal stirring. In the Grand Manan Channel so close an approach 
to verticle homogeneity is maintained throughout the summer that the maximum 
vertical range so far recorded for August has been only about 0.08 per mille, as 
follows: 
Salinity 
.6 .8 32 .2 .4 .6 .8 33 .2 .4 .6 .8 34 .2 .4 
— 
\ 
V 
0 t 

— 
a 
\ 
> 
s 
\ 
\ 
\ t 
\ 
1 
\ ' 
\ 
V 
\ 
\ 
\ 
8* 
\ 
\ 
> 
\ 
N 
\ 
X - 
ffi\ 
\ 
X 
D A 
\ 
\ 
Y - 
> 
k 
\ 
V 
\ 
\ 
\ 
\ 
\ 
\ 
\ 
\ 
\ 
1 
1 
\ 
\ 
X) 
\ 
\ 
l 
\ 
\ 
0 1 
® 
8951 - 28 - 
-50 
