PHYSICAL OCEANOGEAPHY OF XHE GULF OF MAINE 



567 



basin of the gulf. In the Bay of Fundy, however, access to which for the inflowing 

 bottom drift is hindered by the contour of the sea floor (p. 691), the temperature was 

 virtually uniform from the 75-meter level downward on May 10, 1918 (about 2°), 

 while in 1917 it was slightly lower (2.11°) at 175 meters than at 75 to 100 meters 

 (2.2° to 2.8°) on the 4th of the month (Mavor, 1923). The deep sink inclosed by 

 Jeffreys Ledge (recalling the Bay of Fundy in the contour of its floor, though smaller 

 in area) was Ukewise nearly uniform in temperature from 100 meters (3.45°) down 

 to 175 meters (3.7°) on May 14, 1915 (station 10278). 



Whether the bottom water of the gulf basin cools or warms slightly from April 

 through May, or whether the temperature remains virtually constant there, depends 

 on the pulses just discussed (p. 555) and on the quantity and temperature of water 



Fig. 34.— Temperature at a depth of 40 meters, May 4 to 14, 1915 



brought in by them. If the inward drift over the bottom continues comparatively 

 constant, little or no change is to be expected in the bottom temperatm-e. If, how- 

 ever, the flow slackens or ceases, vertical circulation, from which no part of the gulf 

 is free, will tend to equalize the temperature vertically; that is, to cool the deepest 

 water while warmiug the overlying stata as they mix together. A pair of stations in 

 the southwestern part of the basin for February and May, 1920, illustrate just this 

 change, the slight rise in temperature with increasing depth from 100 meters down- 

 ward to bottom in 150 meters, which was recorded for February 23 (station 20048), 

 giving place to perfect vertical homogeneity by May (station 20127), while the 140 

 to 150 meter level cooled from 4.87° to 3'8° and the 100-meter level warmed from 

 3.54° to 3.8° during the interval. 



