584 



BULLETIN OF THE BUREAU OF FISHERIES 



on this cruise, the presence of 6°-water there on May 4 (p. 566) at depths greater 

 than 225 to 230 meters, and again on August 31 of the same year (station 10307), 

 makes it ahnost certain that this was also the case in June. 



The relationship which this warm bottom stratum bears to the cooler water above 

 it and to the indraft from outside the edge of the continent, is made more graphic by 

 the accompanying profile, running from the Eastern Channel westward and inward 

 along the basin (fig. 44).'° Obstructed on the north by the topography of the sea 

 floor, this warm bottom water reaches the western part of the basin off Cape Ann 

 via the southern branch of the trough, a route that entails its rising over the inter- 

 vening ridge to within 190 to 200 meters of the surface. 



Fw. 43.— Temperature at a depth of 100 meters, Isst half of June, 1915. (The Bay of Fundy is according to Mavor, 1923.) 



It is probable that overflows of this sort are intermittent — frequent enough, how- 

 ever, to maintain the bottom temperature of the western bowl fractionally above 6° 

 for most of the year. The greater thickness of the warm bottom stratum in the 

 southeastern side of the basin (into which the Eastern Channel opens) than elsewhere 

 in the gulf corresponds to the proximity of the source of supply; and it is not 

 unhkely that bottom temperatures of 7° or higher would have been found there at 

 the end of June had readings been taken in depths greater than 275 to 300 meters. 



In horizontal plan the bottom water of 6° takes the form of a Y, following the 

 outlines of the trough of the gulf; its approximate outlines for May and June, 1915, 

 are shown in the accompanying chart (fig. 45). 



"The deepest readings in the western side of the basin are borrowed from the May station (10267). 



