for the dark silty clay was 0.0018 millimeter. The percentages of sand, 

 silt, and clay size particles for the gray-green material were 61, 10, 

 and 29, respectively. The stiff dark clay was composed of 177» sand 

 size particles, 207 o silt size, and 637, clay size. A grain size analysis 

 was also performed on a sample from the apparently mottled zone. The 

 results revealed an intermediate value for median diameter (0.03 milli- 

 meter) and intermediate percentage of fine-grained material (sand size 

 = 46%; silt size - 14%; clay size = 40%). The Unified Classification 

 System defined the gray-green material as a clayey sand (SC), the 

 mottled material as inorganic silts and very fine sands with slight 

 plasticity (ML), and the stiff dark clay as an inorganic silt of high 

 compressibility (MH) . The same materials were considered clayey sands, 

 sandy clays, and sandy clays, respectively, by the Trilinear Classifi- 

 cation System. Carbonate carbon and organic carbon varied between 2% 

 and 67o . 



Vane Shear Strength and Index Properties . The strength and index 

 properties are plotted in Figures 12 and 13. Strength measurements in 

 the upper portion of the core are suspected, since drainage undoubtedly 

 occurred during sample testing. The lower increment, predominantly clay 

 in size, probably represents the strength at that depth. The liquid 

 limit of this increment exceeded the original water content of the sample. 

 This behavior suggests that the sediment was above sea level at some time, 

 and that desiccation may have occurred. 



Station J 



Geologic Description . Station J is located north of the Van Diemen 

 Rise on the Sahul Shelf. The site has a water depth of 50 fathoms. A 

 system of channels, terraces, and flat-topped banks characterize the 

 bottom topography. The shelf is thought to have been above sea level 

 during an early geologic period (Van Andel and Veevers , 1967). The 

 sediments of the Timor Sea are generally thin. The coarser fractions 

 are predominantly calcareous, while the fines are predominantly silts 

 and clays of terrigenous origin. Deposits are continuously reworked by 

 burrowing animals. Van Andel and Veevers (1967) found that the sediments 

 near the site were dusky yellow-green shelly sands. 



Sediment Identification . The gravity corer obtained 115 centimeters 

 of sandy clay. The upper 40 centimeters of sample seemed to exhibit a 

 greater concentration of shell debris. Both the Unified Classification 

 System and Trilinear System considered the material a clayey sand (SC). 

 The median diameter of the material was approximately 0.08 centimeter. 

 Two core increments were tested for grain size. The percentage of sand, 

 silt, and clay size particles in the first was 73, 9, and 18; while the 

 second had values of 71, 12, and 17. Almost 10% of the material was 

 carbonate carbon in origin. The values of organic carbon content were 

 low (less than 1%) . 



28 



