arid, pelagic sedimentation now dominates the depositional processes. 

 Fairbridge (1966) states that the red clays often merge locally with 

 radiolarian oozes. Cores taken during the MONSOON Expedition (Scripps 

 Institute of Oceanography, 1964) suggest that surface samples are fine- 

 grained and green to blue in color. 



Sediment Identification . The gravity corer obtained 130 centimeters 

 of homogeneous gray silty clay. Approximately 5 centimeters of rustic- 

 colored gray clay were detected at the top of the core. Visual examina- 

 tion found no other distinctive layers. The Unified Classification 

 System defined the soil as an inorganic silt of medium compressibility 

 (MH) . The Trilinear System classified the material as a clayey silt. 

 The material had a median diameter of 0.007 millimeter. The percentages 

 of sand, silt, and clay size particles were 1, 57, and 42, respectively. 

 Carbonate carbon and organic carbon constituted less than 0.57, of the 

 sample. 



Vane Shear Strength and Index Properties . The vane strengths and 

 index properties are plotted in Figure 18. Strengths increase consis- 

 tently with depth in the upper 75 centimeters. Beyond that depth a 

 substantial strength increase occurs. Two theories might account for 

 the significant increase. Either a change in sediment properties 

 occurred or the sample densified during the coring process. The validity 

 of vane shear tests on this sample might also be questioned. Since 

 the material is predominantly silt sized, drainage during shear would be 

 expected. The index properties also behave somewhat erratically. 



Station N 



Geologic Considerations . Station N is located west of the northern 

 end of Sumatra. The site has a water depth of approximately 2,400 fathoms. 

 The northern extension of the Java Trench separates the site from most 

 of the effects of terrestrial runoff (Ewing, 1969). In a similar manner, 

 the Nintyeast Ridge isolates the area from turbidites originating on the 

 Ganges Cone. Fairbridge (1966) suggests that the sediments of the area 

 are often characterized by globigerina oozes. 



Sediment Identification . The gravity corer obtained 150 centimeters 

 of tan silty clay. The sample appeared homogeneous throughout its length. 

 The Unified Classification System considered the material an inorganic 

 silt of high compressibility (MH) . The Trilinear System defined the same 

 soil as a silty clay. The soil had median grain diameters of 0.003 

 millimeter (30 to 40 centimeters) and 0.0015 millimeter (120 to 130 

 centimeters). The percentages of sand, silt, and clay size particles in 

 the upper layer (30 to 40 centimeters) were 13, 30, and 57, respectively. 

 A similar determination performed on the 120 to 130-centimeter increment 

 found 77o sand size particles, 22% silt size, and 717o clay size. Carbonate 

 carbon and organic carbon accounted for less than 3.57o of the upper 

 increment and less than 5 . 57> of the lower increment. 



31 



