46 Hydeography of the Stream 



because water masses that may be motionless are included as part 

 of the Stream because they lie below a surface current. 



Since the Gulf Stream is a boundary or front in the western 

 North Atlantic between the slope water and the Sargasso Sea we 

 may define it as follows : it is a continuous band stretching from 

 the continental shelf off Cape Hatteras to the 50th meridian of 



Fig. 20. Temperature section across the Gulf Stream, Chesapeake Bay to 

 Bermuda, April 17-23, 1932, according to Iselin (1936, fig. 5). 



longitude, south of the Grand Banks of Newfoundland. This band 

 consists of a pronounced pressure gradient between the warm, 

 highly saline water to the south, and the colder, fresher water to 

 the north. Using this definition then, the inner and outer Hmits 

 or edges of the Gulf Stream can be defined as the points where 

 this pressure gradient becomes zero. These points can be located 

 only if deep, closely spaced temperature and sahnity data are 



