and upper part of the slope are relatively 

 smooth, with only minor undulations in both 

 slope-parallel and slope-normal directions. 

 However, below the 500 fms isobath the bot- 

 tom morphology becomes appreciably rougher, 

 the slope being modified by many ridges and 

 hollows with a slope-normal relief often ex- 

 ceeding 150 fms. This rugged topography ex- 

 tends on to the uppermost part of the continen- 

 tal rise but beyond the 1200 fms isobath the re- 

 lief is less conspicuous. Here a few large, iso- 

 lated ridges are separated by wide, relatively 

 smooth depressions (Fig. 1). 



The ship's track for cruise RoS, (Fig. 2) 

 follows a broadly rectilinear pattern compris- 



ing legs which are alternately parallel and per- 

 pendicular to the course of the canyon axis. 

 Such a track (total of 502 n.miles) not only 

 provides extremely useful bathymetric data 

 from PESR records but also facilitates the 

 creation of a net of bottom camera stations 

 which encompasses not only the canyon itself 

 but also the adjacent areas of the shelf, slope 

 and rise (Fig. 3, Table 1). Slope corrections 

 were applied to soundings after the method of 

 Shalowitz (1930). Soundings from Coast and 

 Geodetic Survey Charts H5350, H6200 and 

 H5713 were utilized to amplify the bathyme- 

 tric data in a few areas of the shelf and upper 

 slope. 



