PHYSICAL OCEAN OGBAPH Y OF THE GULF OF MAINE 
665 
Massachusetts Bay is warmest), the 20-meter level early in September, 40-meter 
level about the 1st of October, and. the 70-meter and 100-meter levels during that 
month or the next. 
3. NEAR MOUNT DESERT ISLAND 
Off Mount Desert, where tidal stirring keeps the water thoroughly mixed, surface 
to bottom, throughout the year, the column cools nearly uniformly at all levels 
during the autumn and warms only slightly more rapidly at the surface than in the 
deeper strata during the spring (fig. 88) , so that the period when the surface is more 
than 1.5° to 2° warmer than the 20 to 40 meter level averages 2 to 3 months instead 
of 5 to 6 months, as in Massachusetts Bay; and the 40-meter level warms to its 
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Fig. 87. — Composite diagram of the seasonal variations of temperature at Prince station 3, in the Bay of Fundy, between 
Grand Manan and Petite Passage, from November, 1916, to November, 1917, from Mavor’s (1923) data 
maximum for the year only a month or so later than the surface, instead of about 2 
months later. The autumnal equalization of temperature also takes place by the 
first week of October near Mount Desert, a month earlier than in the deep part of 
the Bay of Fundy (fig. 87) but only a week or two earlier than in Massachusetts 
Bay (fig. 86). 
4. WESTERN SIDE OF THE BASIN 
Probably the western arm of the basin (fig. 89) is less subject to tidal stirring in 
its upper strata than any other part of the gulf. Therefore, it is not surprising to 
find the seasonal rise and fall of temperature of its superficial stratum (surface to 40 
meters) closely reproducing that of Massachusetts Bay, except that the temperature 
