BOTTOM PHOTOGRAPHY 



Camera stations were located throughout the channel at predetermined positions. 

 Although the photographs from this study cannot be considered to be representative of 

 the entire channel bottom, the close-spaced coverage obtained along the fairly ex- 

 tensive tracks provides excellent representation in the area photographed, and, from 

 these photographs and the work of Armstrong (1953) and Athern (1962 b) a general idea 

 of the microrellef can be obtained. 



Camera lowerings at Stations 1, 2, and 3 were occupied while the ship was at 

 anchor, and the lowering at Station 4 was made while drifting. The ship's position 

 was plotted and annotated during the camera lowerings on a Decca Hi-Fix plotter, 

 and a graphic record of the ship's position, hence, the camera location (± 10 feet), 

 was obtained during the two-hour period while the camera was in operation off the 

 bottom (Fig 14). 



Camera lowering Station 4 is represented on Figure 14 by a line trending north- 

 northwest across the center of the TOTO off High Cay. The paths followed by the 

 other camera stations (1, 2, and 3) are also presented In this figure, and variations in 

 ship location while at anchor are graphically demonstrated. In the graph of station 2, 

 the ship completed one cycle of it's swing on the anchor cable, and the camera was 

 brought up while halfway along the return swing. 



The graph of Station 1 demonstrates the extreme to which the ship varied in posi- 

 tion while anchored. In this instance, the vessel was subject to a fairly long-period 

 pitch superimposed on the arc traversed around the anchoring point. The combination 

 of swinging and surging produced a figure 8 pattern which the camera system followed. 

 The procedure of plotting the ship movement, annotating the plot, and including a 

 synchronized clock in the data chamber of the camera permits calculations to enable 

 one to delete duplications of track coverage where present. 



Two out of four of the camera stations produced pairs of stereo photographs (Stations 

 1 and 4), while at the remaining stations malfunctioning of one of the two cameras re- 

 sulted in only one roll of exposures during the course of the lowering. The photographs 

 generally cover an area approximately 13.5' x 8' or 108 ft2, and overlapping of pairs 

 exceeds one half the area photographed. 



Camera Station Data 



Station 1 



Depth: 1,250 meters 



Number of Exposures: 362 



Length of Camera Track: 457 meters 



Track Position: 23° 27.4'N, 76° 58.8'W (Coordinates for center of track) 



Camera Performance: Stereographic pairs obtained from all exposures. 



58 



