Station H 



Geologic Considerations . Station H is located in the Coral Sea 

 Basin, the largest of three basins in the Coral Sea. The water depth at 

 the site is approximately 2,200 fathoms. An extremely flat abyssal 

 plain characterizes geologic conditions at the site. Frause (1967) 

 states that a thin layer of pelagic clay (12 to 40 centimeters) covers 

 most of the basin. An olive-colored silt containing carbonized wood 

 fragments lies beneath the clay. The silt is thought to be a turbidity 

 deposit originating from subareal New Guinea (Fairbridge, 1966). 



Sediment Identification . The gravity corer obtained 177 centimeters 

 of tan silty clay. A visual examination found no evidence of layering. 

 The Unified Classification System defined the sediment as an inorganic 

 silt of high compressibility (MH) , while the Trilinear System considered 

 the sample a sand-silt-clay. The sediment had a median diameter equal 

 to 0.0095 millimeter. The percentages of sand, silt, and clay size 

 particles were 34, 22, and 44, respectively. Carbonate carbon and organic 

 carbon accounted for approximately 2.5% of the sample. 



Vane Shear Strength and Index Properties . The strength and index 

 properties are plotted in Figure 11. A noticeable discontinuity occurs 

 in the original strength profile. Since the remolded strength and soil 

 plasticity do not exhibit a similar trend, the discontinuity is attributed 

 to sample disturbance. The low L-versus-D ratio suggests that the dis- 

 turbance occurred during handling. 



Station I 



Geologic Considerations . Station I is located in the Arafura Sea, 

 north of the Gulf of Carpentaria and west of the Torres Straits. The 

 site has a water depth of approximately 26 fathoms. Fairbridge (1966) 

 states that terrigenous deposition is slow on the Arafura Shelf and that 

 bottom sediments are generally glauconitic sand and calcareous mud. 

 Recent geologic evidence tends to suggest that most of the Arafura Shelf 

 was above sea level. 



Sediment Identification . Two sediment cores were obtained from the 

 station. The first sample, 58 centimeters long, was comprised of 20 

 centimeters of gray-green shelly, sandy clay above 12 centimeters of the 

 aforementioned material mottled with a stiff dark silty clay. The re- 

 mainder of the core was stiff dark silty clay. The other core was 83 

 centimeters in length, and it exhibited similar layering; however, the 

 depth of the layers varied. The soils profile for this core consisted 

 of 45 centimeters of gray-green shelly, sandy clay above 12 centimeters 

 of mottled shelly, sandy clay and stiff dark silty clay. Beneath the 

 mottled clay was the stiff dark silty clay. The median diameter of the 

 gray-green material was 0.09 millimeter, while the corresponding value 



27 



