Large-Scale Features 



41 



Bathymetric features along the Stream. — The course of the currents in the 

 Gulf Stream System seems to be determined in part by the submarine 

 topography of the western North Atlantic. Fig. 16 is a bathymetric chart 

 of the region according to Tolstoy (1951, pi. 1). Fig. 17 shows the bathy- 

 metry through the Straits of Florida, obtained from Hydrographic Office 

 charts . The depths in these two figures are given in fathoms ( 1 fathom = 6 ft . ) . 



80*= 



75= 



70' 



65* 



60° 



55' 



Fig. 16. BathjTnetric chart of the western North Atlantic in contours of 

 500 fathoms, according to Tolstoy (1951, pi. 1). Sea mounts are shown in the 

 upper right quarter of the chart. 



The Stream continues on a shelf of about 800 m. depth along the Blake 

 Plateau to about 33° N., where it leaves the shelf. From Cape Hatteras 

 northeast, the Stream flows through a region that is about 4000-5000 m. 

 deep. Since the high- velocity part of the Stream does not penetrate much 

 below 1500 m., it would be difficult to see how bottom topography could 

 influence the Stream here, were it not for the recent discovery (by echo 

 sounder) of numerous sea mounts in the area. Fig. 16 shows the position 

 of some of these. 



Farther east the North Atlantic Current encounters the Mid- Atlantic 

 Ridge, which, over large areas, comes to within 2000 m. of the surface. 



In order to aid the reader in locating the various sections and positions 

 referred to throughout the text, fig. 18, an index chart has been prepared. 



