Obviously, the corer utilized on the cruise exceeded some of the 

 maximum values defined by Hvorslev (for example: A = 39 to 87%: C = 0%: 

 and C = 8 to 17%) . About half the cores also had length-to-diameter 

 ratios larger than 20, and none of the corers utilized a piston. 



It is generally believed that the soil adiacent to the wall of the 

 corer is weakened most (Orav, 1957). Published data also show that the 

 strength of the sample increases as the distance from the wall increases 

 (Burmister, 1936). Unfortunately, the magnitude of strength decrease in 

 the center portion of the sample varies from sample to sample. A greater 

 loss usually occurs in soft soils than in stiff or strong soils. The 

 top few centimeters of a core and the lower portion of a long (L/D 

 greater than 20) core are expected to be disturbed to the greatest degree. 



Since the surface area of vane rotation is less than 3.5% of the 

 sample's cross-sectional area, the strength loss due to large area and 

 clearance ratios should be small. The magnitude of loss was calculated 

 to be approximately 10% by extrapolating the strength difference between 

 the gravity corer at an area ratio of 39% and the trip corer at an area 

 ratio of 50% back to strengths at an area ratio of 20%. No absolute 

 magnitude is to be placed on the strength loss due to large length to 

 core diameter ratios; however, the effect is believed to be significant 

 for weak soils. 



In the following paragraphs, a description of the sediments from 

 each station is presented. The stations are designated bv capital letters 

 The letter T in some designations indicates that the sample recovered bv 

 the trip corer was used in the analysis. 



Station A 



Geologic Considerations . Station A is located 

 north of Palmyra, northern island in the Northwest 



Christmas Island Ridge (also called the Line Islands bv Menard, 1964) . 

 The particular site, located in 2,850 fathoms of water, exhibited char- 

 acteristics typical of an abyssal hill environment (Hamilton, 1970). 

 Fine-grained pelagic materials dominate the sediments of the area 

 (Fairbridge, 1966). 



Sediment Identification . The gravity corer obtained 280 centimeters 

 of homogeneous deep-sea red clay. A visual examination of the core 

 (through the core liner) found no evidence of sample layering. The 

 Unified Classification System, which describes a soil bv its plasticitv 

 characteristics and grain size, designates the materia] as an inorganic 

 silt of high compressibility (MH) . The Tri] inear Classification Svstem 

 considers the same material a silty clav. The median diameter of an 

 increment from the core is 0.0024 millimeter. Clav size particles 

 constituted approximately 66% of the sample. Silt particles accounted 

 for 29% of the material, while sand formed the remainder. The carbonate 

 carbon and organic carbon contents are 2.12% and 0.01%, respect ivel v . 



22 



