THE GULF OF ST. LAWRENCE. 



The early investigations in this region had for their object the determination 

 of conditions in the two straits by which the Gulf of St. Lawrence is connected 

 with the ocean; as a basis for understanding the whole region. The main entrance 

 is by Cabot strait between Cape Breton and Newfoundland; and the other is by 

 Belle Isle strait. An examination of the Gulf area in general, showed that in 

 the southwestern side the water was warmer and of lower density than in the 

 northeastern arm running towards Belle Isle strait. 



The density in the open Atlantic, from seven determinations made off the 

 south and southeast coasts of Nova Scotia, was found to range from 1 • 0237 to 

 1-0242, which is practically the same as in this northeastern portion of the 

 Gulf. It may, therefore, be stated broadly, with regard to these two divisions 

 of the Gulf, that throughout the northeastern portion the average surface density 

 ranges from 1-0235 to nearly 1-0245; while in the southwestern portion, the 

 density is below 1-0235, ranging usually down to 1-0220, and falhng in the 

 Gasp^ current itself to 1-0210. 



The divid^ing line between these two portions of the Gulf runs approximately 

 from Southwest Point, Anticosti, to a point in the middle of Cabot strait. 

 The density in the northeastern portion is practically the same as in the open 

 Atlantic. The lower densities found in the southwestern portion of the Gulf, 

 correspond with the general set or drift across the Gulf in the direction of a line 

 from Gaspe to Cape Breton. This set is most accentuated in the Gaspe current 

 and in the outward current on the west side of Cabot strait. 



Another general feature discovered, was an extremely cold layer of water, 

 lying usually between the depths of 30 and 50 fathoms. The surface temperature 

 in the summer season ranges from about 50° to 65°, and in proceeding down- 

 wards this temperature gradually falls, till at the depth indicated it is practically 

 at the freezing point. Where the greater depths are met with, the water below 

 this is appreciably warmer. The density of this deeper water at 100 and 150 

 fathoms, affords an explanation for the otherwise anomalous fact that the 

 colder water at 50 fathoms is found to float upon it. 



It is probable that this cold layer extends very generally over the Gulf area. 

 In the vicinity of Belle Isle strait, the same low temperatures are found at the 

 depths above indicated; although there the temperature towards the surface 

 also remains low as a rule. Elsewhere the water becomes warmer during the 

 progress of the season, but only to a moderate depth. This cold layer must have 

 a relation to the fish and other marine life in the Gulf area; as the extensive 

 banks at 30 and 40 fathoms are continually in this cold water. There is also 

 a belt on the bottom at about this depth, which runs parallel to the shore, and 

 often has a considerable width. 



It is evident that the temperature and density of the water proved of value 

 from the outset in tracing the movements of the water. These general explan- 

 ations may also serve as a guide in following the details hereafter given. 



In the following table, the temperature at 50 fathoms where the water is 

 coldest, was usually taken with both types of thermometer already described, 

 as a check for the minimum. 



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