35_ 



Silt tended to accumulate in the deeper (>5 m), low relief areas in the pit. A few small 

 patches of rock were noted along this line, one of which was found on a bathymetric feature 

 near the mid-point of the transect. 



The depth profile for Transect B displayed a bottom feature with vertical relief of 

 2.5 m and a diameter of 50 m near the center of the pit (Figure 3-11). The margins of this 

 feature were composed of fine sand and the sediments over the relatively flat top of the 

 mound were classified as silt. Based on its location relative to the disposal buoy (southeast), 

 this feature is likely the product of recent dredged material disposal activity. 



Transect C also represents a transverse pass over the borrow pit. Once again, small 

 patches of silt, fine silty sand, fine sand with shell, and a limited amount of pebble and 

 cobble sized rocks were observed within the video record (Figure 3-12). The video sled 

 passed 20 m northeast of the disposal buoy position as it was towed east-southeast across the 

 borrow pit. Similar to the interpretations of Transect A, the surface sediments in close 

 proximity to the MCDA buoy position were characterized as fine, silty sand. No obvious 

 visual distinctions were observed between ambient sediment and the surface of the recent 

 dredged material deposit. The depth profile for Transect C showed limited vertical relief to 

 the west of the buoy position before the bottom gradually sloped to the deepest portion of the 

 pit (water depth of 10 m). Silt was the major constituent of the sediments within the deepest 

 portion of the pit. 



Transect D was the second longitudinal pass made over the Morris Cove borrow pit, 

 and designed to document the composition of sediment along the eastern margin of the pit. 

 Due to unreliable navigation data from the DGPS unit during the occupation of Transect D, 

 the position of the video sled was approximated for the majority of this line. The 

 bathymetric data were used in conjunction with the NOAA chart pictured in Figure 3-13 to 

 place the line along the eastern margin of the borrow pit. Overall, a similar lithology and 

 distribution of sediments were observed, relative to other transects. Fine sand with varying 

 shell content was noted in areas near the walls of the pit and silt was found over the flat areas 

 within the pit. The video data collected in the southern portion of the borrow pit suggested 

 that seafloor composition east of the buoy position is quite patchy. 



Transect F was a third transverse pass made over the borrow pit and sampled an area 

 approximately 25 m southeast of the MCDA buoy position. In general, Transect F displayed 

 similar combinations in bottom composition relative to Transects C and B with silt, shell lag, 

 and sand represented in the video images (Figure 3-14). A strong bathymetric feature east of 

 the MDCA buoy with a minimum depth of 5.5 m was detected in the depth profile. 

 However, due to the lack of baseline bathymetric data, it is difficult to discern whether this 

 feature is the direct result of dredged material deposition or simply enhanced by the 

 placement of 14,000 m^ of sediment. 



Monitoring Cruise at the Morris Cove Borrow Pit 



