26 



MARION AND GENERAL GREENE EXPEDITIONS 



tral portions of the Labrador Sea partake of a slow cyclonic mo- 

 tion. The West Greenland Current in this scheme is really two flows 

 in one — (a) the East Greenland Current and (h) the Irminger Cur- 

 rent ; ^ which in their extension around Cape Farewell become reen- 

 ergized along the west coast of Greenland and are renamed for that 

 region. The Labrador Current likewise is an extension of the Baffin 

 Land Current and the West Greenland Current. 



A vertical section of the Labrador Sea between points A and B, 

 figure 5, shows that tiie greatest changes in phj^sical character occur 

 at the sides of the basin as represented by the line M~N (fig. 6). 

 Three principal water types cliaracterize the northwestern North 



F igure 6.— A schemat ic ver tical cross sect ion of the Labrador Sea, Belle Isle to Cape Farewell. 

 ^%%%: Coastal water. $$$^$$$$j Arctic water. |./v.'vj Atlantic water. MiiM Mixed Labrador Sea water. 



Atlantic, viz, coastal, Arctic, and Atlantic. Their mixture (dis- 

 cussed in chap. VIII), with a remarkably small range of approxi- 

 mately 1° C. temperature and 0.06%o salinity, fills ai)proximately 

 90 percent of the Labrador Basin. 



In assigning names to water masses in the sea it should always be 

 remembered that values are comparative only. Variations in the 

 mixing processes, as regards time and place, constantly prevail. This 

 fact precludes any possibility of assigning definite limits of tem- 

 perature and salinity. An interpretation of the circulation, based 

 solely upon the relative proportions and degree of purity of a par- 

 ticular tyi^e of water present in a given mass, may often prove mis- 

 leading. Detecting the presence of waters from known sources re- 

 quires a thorough familiarity with the region investigated, })articu- 



^ For a description of the general position and beliavior of the Kast (ireenland Current 

 and n-mingcr Current east of Cape Farewell prior to entering the Labrador Sea see 

 Nielsen (1928). 



