Station P 



Geologic Considerations . Station P is located in the Bay 

 of Bengal, northeast of Ceylon. Most of the sediments in 

 the area have been carried from the continental shelfs by turbidity 

 currents (Ewing et al , 1969). A distribution chart by Siddquie (1967) 

 shows that the sediments in the area are silty clays. Less than 57, of 

 the material has grain sizes in excess of 0.1 millimeter. Calcium car- 

 bonate accounts for 57= to 107 of the sediments. The depth at the parti- 

 cular site is approximately 1,800 fathoms. 



Sediment Identification . A 90-centimeter gravity core and a 25- 

 centimeter trip core were obtained at Station P. The upper 31 centi- 

 meters of sample were composed of a brown clay. The brown clay was 

 underlain by gray-green clay. The Unified Classification System defined 

 the brown and gray-green clays as inorganic silts of high compressibility 

 (MH) . The Trilinear System classified both materials as silty clays. 

 The median diameters of the two materials were approximately .001 milli- 

 meter for the brown clay and 0.0022 millimeter for the gray-green clay. 

 The brown clay consisted of 127, sand size particles, 137. silt size, and 

 757. clay size. The percentages of sand, silt, and clay size particles 

 for the gray-green material were 6, 29, and 65, respectively. Carbonate 

 carbon and organic carbon accounted for 47> of the brown clay and 27, of 

 the gray-green clay. 



Vane Shear Strength and Index Properties . The vane strengths and 

 index properties are plotted in Figure 2 2. A severe discontinuity occurs 

 in the original strength profile. The discontinuity roughly corresponds 

 to the transition from the brown clay to gray-green clay. A decrease in 

 plasticity index and an increase in water content are also noted for this 

 zone. Liquidity index also increases substantially for this zone. 

 Although sample disturbance may have occurred, it is not thought to be 

 the cause of the discontinuity. 



Station Q 



Geologic Considerations . Station Q is located in the central portion 

 of the Andaman Basin. The water depth at the site is approximately 

 1,650 fathoms. Sediments at the site are predominantly terrigenous in 

 origin. The Irrawaddy and Salwean Rivers deposit enormous amounts of 

 sediment into the area. A system of channels and canyons assists in 

 diverting these flows to the central basin (Fairbridge, 1966). The 

 central basin is presently accumulating fine olive-green clays and deltaic 

 sediments (Redolpho, 1964). Volcanic ash and foraminiferal oozes occur 

 in some areas. 



Sediment Identification . A 70-centimeter gravity core and a 20- 

 centimeter trip core were obtained from the site. A thin, 3-centimeter 



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