widespread appearance of sand at the sediment surface for the first 

 time at CS-1. 



The cap deposited at CS-2 in May 1983 predominantly 

 consisted to very fine sand (4-3 phi) . Post-capping bathymetric and 

 REMOTS® surveys showed the cap had a maximum thickness of 1.4 meters 

 at the mound apex, with most of the sand concentrated within a radius 

 of 100 to 200 meters. Beyond this, cap thickness decreased from 4 cm 

 to cm within a 400 meter radius of the mound apex (SAIC, 1984) . As 

 early as September 1984, the sand cap was becoming less recognizable 

 due to the addition of silt-clay. This was attributed primarily to 

 bioturbation resulting in mixing of the sand cap with underlying fine- 

 grained sediments, similar to what was observed at the STNH-N mound. 

 Some sedimentation of silt-clay into the area from tidal resuspension 

 of the ambient seafloor may also have contributed. In the August 1985 

 survey, a distinct sand cap could not be seen, and the major textural 

 mode for most station replicates was > 4 phi. At the same time, 5 

 stations located on the western side of the mound were found to have 

 a layer of silt-clay overlying the original sand cap. This was 

 attributed to enhanced sedimentation on the "lee-side" of the mound. 

 The present survey revealed that all stations (except 600N) had a 

 major textural mode of silt-clay (> 4 phi) . The silt-clay over sand 

 stratigraphy described in 1985 apparently has been lost through 

 bioturbation. The only station which resembles the original sand- 

 over-mud stratigraphy is CS-1 station 600N (Figure 3-42) . A minor 

 sand component can be seen at other stations. This sand may represent 

 the remnants of the original sand cap or may be related to the post- 

 Hurricane Gloria distribution of sand from nearshore (as described for 

 CS-1 above) . 



Disposed dredged materials were present at all stations 

 except 4 00N at CS-1; at, CS-2, no apparent dredged material was 

 detected at stations 400E, 600E, 400W, 600W, 400N, 600N, 400S and 

 600S (Figure 3-43) . The optical "signature" of disposed materials 

 apparently has been "erased" from the flanks of CS-2. The fact that 

 disposed material was detected at more stations at CS-1 than CS-2 is 

 probably related to the more recent disposal activities that have 

 taken place immediately adjacent to CS-1 (between 1984 and 1985) . 



The frequency distributions of small-scale boundary 

 roughness for both CS-1 and CS-2 showed a major mode at the 0.8 cm 

 class interval (Figure 3-44) . The mean values for each mound were 

 0.86 ± 0.28 cm and 0.91 ± 0.30 cm, respectively. These values did 

 not differ significantly from those obtained in August 1985. 



The post-Hurricane Gloria REMOTS® survey of October 18, 

 1985 showed that the mean apparent RPD depths were significantly less 

 than those measured in August 1985. Storm-associated erosion reduced 

 the apparent RPD depths to less than 3 cm below the sediment-water 

 interface. Since October 1985, the mean apparent RPD depths have 

 increased at both mounds, but at unequal rates. Most apparent RPD 

 depths at CS-1 fell within the 3.0 cm class interval (mean = 3.53 cm 



18 



