The corer was not designed to obtain engineering quality samples as 

 defined by Hvorslev (1949). However, it is typical of the intermediate- 

 size piston corers currently in use by the oceanographic community 

 (Clausner and Lee, 1975). The corer has obtained samples up to 40 feet 

 (12m) in length in very soft sediments. The longest sample CEL has 

 obtained is 28 feet (8.5 m) (on an earlier cruise). 



The spade-type box corer obtains samples that are only 2 feet (0.6 m) 

 in length. However, the cross-sectional area of the sample is so 

 large (12x8 inches) (300 x 200 mm) that almost completely undisturbed 

 samples are guaranteed. These samples were taken to determine the 

 maximum quality of sample that could be achieved and to use them in 

 triaxial testing to simulate strength profiles to greater subbottom 

 depths (as explained later). Also, high quality samples were needed for 

 CEL's soil dynamics program. 



Free-fall boomerang cores were taken to determine the general 

 sediment type of a site prior to deploying the vane tower or long-piston 

 corer. A NAV0CEAN0 hydroplastic corer was used at one of the sites 

 after the CEL piston corer was lost. 



Sites Visited 



Table 1 lists the sites that were investigated along with their 

 geographic coordinates. Site I is located north of the Puerto Rico 

 trench in deep water (18,000 feet) (5,500 m) . It was selected as a site 

 with a low calcium carbonate content that would probably contain a 

 pelagic clay deposit. This was found to be the case. Site III is 

 located north of Grand Bahama Island on the Blake Plateau in about 4,000 

 feet (1,200 m) of water. This site was selected as a location with a 

 high calcium carbonate content (calcareous ooze). Site IV is located a 

 few miles (several kilometers) southeast of Puerto Rico in a 6,000-foot- 

 deep (1 ,800 m) enclosed basin. The sediment at this site is a calcium 

 carbonate-rich proximal turbidite (alternating silt and sand layers). 

 Site II was to be located in a deep channel north of Nassau. This site 

 was not visited because of highly irregular bottom topography. 



The cruise was conducted between 23 November and 13 December 1974. 

 During this time the LYNCH sailed from Charleston, South Carolina, to 

 San Juan, Puerto Rico. Some ship time was lost as a result of adverse 

 weather conditions, especially in the vicinity of the Bahamas Islands. 



The in-place vane shear tests, which were conducted from a moored 

 ship, had locations that were within 300 feet (90 m) of each other 

 at each general test site. The cores, taken while the ship was in a 

 drifting mode, are much more widely scattered. The distance between 

 cores at a general site is as much as 3 miles (5 km) . Since the test 

 sites were selected partly for their flatness and areally uniform sediment 

 conditions, it is assumed that variations among properties over the area 

 of a general test site are negleeible. 



