B 



r 



Figure 5. Typical "pinger-traces" of camera-rig dur- 

 ing descent, bottom photography near the sea-bed, 

 and ascent as indicated on PESR record. 



(a) Camera Station 23, near shelf-break, north of 



canyon head. 



(b) Camera Station 28, near shelf-break on open 



slope, southwest of canyon. 



P — trace given by pinger attached to 

 camera-rig; 



B — true bottom (sediment-water inter- 

 face) ; 



M — multiple of bottom and pinger-trace. 



tive frame-number and a clock. This allows the 

 position of each frame to be accurately located 

 with respect to the known position of the ship 

 at a given instant of time. Moreover, each 



frame may be linked to timed events on the 

 PESR record, allowing more precise location 

 as to depth of individual frames and groups of 

 frames within each station. 



9 



