IV. MASS PROPERTIES 



A. 8NTRODUCTSON 



Mass physical and classification properties of more than 700 samples from 35 cores 

 were determined In the laboratory. The tests included measurement of: (1) grain size, 

 (2) specific gravity of solids, (3) wet unit weight, (4) water content, (5) degree of 

 pore space water saturation, (6) liquid and plastic limits, (7) void ratio, and (8) com- 

 pressive and/or vane shear strength. From these measurements the following properties 

 were computed: (1) percentage of sand-, silt-, and clay-size particles, (2) grain 

 median diameter, (3) void ratio at 100 percent saturation, (4) porosity, (5) liquidity 

 index, (6) plasticity index, (7) cohesion, (8) sensitivity, (9) activity, and (10) modu- 

 lus of elasticity. The mineralogy of a few samples also was investigated. 



A unit volume of any deep-sea sediment, in simple terms following the conception 

 of Rosenqvist (1955, p. 3), may be considered a two-phase system consisting of: inor- 

 ganic and organic particulate matter, principally mineral grains and skeletons of small 

 plants and animals, and water containing soluble salts. It was not feasible to determine 

 the quantity of salt (loosely-speaking salinity) of the interstitial water in the laboratory 

 program, and no salt corrections have been applied. Computation of percentage of 

 water saturation shows that the void space of samples tested can be considered 100 per- 

 cent saturated with water. Consequently, water content is expressed as porosity or the 

 volumetric weight of water. Organic content was low and gas, when it existed, was 

 considered a negligible quantity. 



Parameters measured in the laboratory are related to the measured distance below 

 the top of each core. The length of each sample tested is graphically shown in Plates I 

 through XXXV by a vertical line. Mid-points of sample lines are connected to show 

 the profile, except for specific gravity where minor variations with depth would be 

 obscured, in the plates, the abbreviations pcf and psi respectively indicate pounds per 

 cubic foot and pounds per square inch; explanation of symbols is given In text and under 

 notation; unless specified, all cohesions were computed from compressive strength tests. 

 The pattern for showing the percentage of sand-, silt-, and clay-size fraction closely 

 follows a standard soil mechanics representation (Anonymous, 1960). 



B . GRAIN SIZE 



Procedure — Most samples were mechanically analyzed in the Hydrographic 

 Office Laboratory using the following method. A 25 g representative sample having 

 a natural water content was placed in a beaker of water and stirred by hand. The 

 resulting suspension then was poured into a milkshake container and mechanically 



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