The Unified Classification System and Trilinear System defined the first 

 two materials as sands with plastic fines (SC) and sands, respectively. 

 The clay material was classified (Unified Classification System) as an 

 inorganic silt with high compressibility and as a sand-silt-clay 

 (Trilinear System). 



Vane Shear Strength and Index Properties . The vane shear strengths 

 and index properties are plotted in Figures 24 through 27. Any strength 

 determination in the upper 75 centimeters of material is probably invalid, 

 since the material was cohesionless (drainage could not be controlled, 

 and coring or vane insertion changes soil density). The high values of 

 strength recorded in the clay probably reflect sediment erosion or 

 desiccation during past decades. 



CORRELATION OF RESULTS 



The sediments tested during this investigation represent materials 

 from the following three physiographic provinces: (1) continental 

 terraces, (2) abyssal plains, and (3) abyssal hills. Continental terrace 

 provinces include all locations on the continental shelf and slope. 

 Sediments, therefore, are primarily terrigenous in origin. The abyssal 

 plain and abyssal hill provinces occur in the deep ocean (beyond the 

 continental terrace) . Terrigenous sediments originating from turbidity 

 currents dominate the former province, while pelagic materials (red 

 clays and oozes for example) characterize the latter. In some cases a 

 pelagic material occurs in an abyssal plain province if the source of 

 terrigenous material has been exhausted. However, the province is still 

 considered an abyssal plain, since the underlying terrigenous deposits 

 determine geomorphic characteristics of the area. 



Unfortunately, the continental terrace samples tested contained a 

 high percentage of sands. The high percentage of sand, in turn, inval- 

 idated the results of the vane shear tests (see STRENGTH CONSIDERATION - 

 Vane Shear Strength and DISSCUSSION OF RESULTS - Stations I, J, and R 

 for further explanation). Consequently, no correlations between strength 

 and laboratory properties were attempted for the continental terrace sed- 

 iment regime. 



Sediment samples from the abyssal hill and abyssal plain provinces 

 met most of the criteria required for vane shear testing. Although 

 disturbance was suggested in several instances, the samples as a whole 

 were thought to provide a good indication of the sediment strength. On 

 the basis of this belief, it seemed appropriate to relate the results 

 at one site to the results at another. 



Since two sources of deposition are involved (continental runoff 

 and biogenic activity), results are compared on a provincial basis. 

 Pelagic sedimentation seems to occur at a more constant rate than the 

 episodic deposition by turbidity currents; therefore, a better correlation 

 was expected between sediments originating from abyssal hill provinces. 



35 



