Surflcial porosities are of particular interest to investigators in sedimentation and 

 engineering. An early study of nearshore Atlantic Ocean "muds" resulted in a range of 

 water contents (porosity?) of 40 to 90 percent (Shaw, 1915). Terzaghi (1925c, p. 912) 

 states that the volume of voids may be 98 percent of the total volume in clays. More 

 recently, Emery (1960, p. 258) reported a maximum submarine sediment water content 

 of 670 percent, corresponding to a porosity of 94.6 percent ; Correns (1937, p. 158) 

 measured a maximum surficial water content of 86.6 percent wet weight, or a porosity 

 of 94.6 percent , in an equatorial Atlantic pelagic clay; and Arrhenius (1952, p. 79 

 and his appendix plate 2.55B-2.55) illustrates a maximum surficial salinity of 105 x 10 , 

 corresponding to a porosity of 91 .4 percent 4 , in the East Pacific eupelagic area. Some 

 examples of the more usual range of fine-grained (Md^>5) surficial porosities in sedi- 

 ments from water depths greater than 400 m are: an average of 86 percent off Southern 

 California (Emery, 1960, p. 258), 35 to 84 percent in the Pacific Ocean (Arrhenius, 

 1952, p. 79), 60 to 86 percent in the Pacific and Arctic Oceans (Shumway, 1960, 

 p. 458-463), 59 to 86 percent in the Gulf of Mexico (Trask, 1953, p. 103, 120), 46 

 to 71 percent in the North Atlantic Ocean (Sutton and others, 1957, p. 796), and, 

 as previously mentioned, 56 to 86 percent in this investigation. Studies of shallow- 

 water marine sediments by Moore (1931), van Andel (1954), Shepard and Moore (1955), 

 and Fu'chtbauer and Reineck (Engelhardt, 1960) show a similar porosity upper limit of 

 about 86 percent. It is apparent that approximately 86 percent appears to represent 

 the usual maximum porosity in fine-grained submarine sediments, although exceptional 

 values may be higher. The observation that the average porosity of a clay at the time 

 of deposition is about 50 percent (Yoder, 1955, p. 506) is not corroborated, 



Shepard and Moore (1955, p. 1580) related the deposition rate in Gulf of Mexico 

 sedimentary environments to the slope of a straight line representing average values of 

 water content related to the percentage of the clay-size fraction. Their data indicated 

 that the steepness of the slope was inversely related to the rate of deposition. A similar 

 relation was found by Seibold (1956, p. 465-467) for sediments from other areas. The 

 application of this hypothesis to the sediments investigated by the writer is equally 

 satisfactory 5 j 



Emery's porosity values computed from equations 12 and 14, assuming a specific gravity 

 of 2.65; Correns 1 porosity values from equations 8, 12, and 14, assuming a specific 

 gravity of 2.7; and Arrhenius' porosities from his equation W = 3.7S - 24, equations 12 

 and 14, and an assumed specific gravity of 2„7 



The following analysis admittedly is subjective. Nevertheless, the calculated relative 

 rates cited were arrived at before Figure 10 was prepared, and the corresponding agree- 

 ment later was found to be good. 



30 



