(a) Experiment 70X-06. The offshore zone, extending from the 

 seaward edge of the inshore zone to the seaward edge of sand, developed 

 from the initial 0.10 slope to a relatively steep slope as a result of the 

 deposition of material seaward of the breaker (see Figs. 10 to 13). The 

 initial deposition during the first 5 hours was at depths greater than 1.1 

 feet and less than 1.6 feet between stations 11 and 16 as shown by the 

 seaward movement of the -1.2-, -1.3-, -1.4- , and -1.5-foot contours (Figs. 

 10 to 13). Between 5 and 22 hours, material was deposited at depths greater 

 than 0.8 foot. The movement of the contour intercepts between 24 and 100 

 hours indicates sand was deposited at all depths greater than -0.7-foot 



and as sand was deposited at the edge of the inshore zone (0.8-foot depth) 

 it slid down the steep slope. After 100 hours the -0.8- and -0.9-foot 

 contours moved little, and the area seaward of -1.1-foot elevation became 

 even steeper as material was deposited between the -0.9- and -1.1-foot 

 elevations. 



No apparent significant lateral variations occurred in the offshore 

 zone of the 6-foot tank, as shown in Figure 32 which compares movements 

 of the -0.9-, -1.3-, and -2.0-foot contours. 



(b) Experiment 70X-10 . During the first 5 hours most of the 

 sediment was deposited at depths greater than -1.0 foot and less than -1.5 

 feet (Figs. 13 to 17). After 5 hours the contour intercepts for depths of 

 -1.0, then -0.9, and then -0.8 foot began moving offshore, indicating that 

 material was being deposited in the same area. As more material moved into 

 this area, a steeper slope developed and the contour intercepts for depths 

 greater than -1.4 feet moved offshore as material slid down this steep 

 face. 



Movement of the -0.9-, -1.3-, and -2.0-foot contours along the five 

 ranges is compared in Figure 33. After the first 5 hours, material was 

 moved offshore at a greater rate along range 1 and and at a slower rate 

 along range 9. The contour intercept for -2.0 feet moved farther offshore 

 along range 9. Along range 1 and range 3 (Figs. 13 and 14) the offshore 

 was steeper; along range 7 and range 9 (Figs. 16 and 17) the offshore zone 

 was slightly flatter and extended farther offshore. 



3. Sediment-Size Distribution . 



The sand for these experiments was the same sand used by Savage (1959, 

 1962) and Fairchild (1970a, 1970b). The median diameter of the Rapid Sedi- 

 ment Analyzer (RSA) method was generally 0.04 millimeter greater than that 

 determined by the dry sieve method (see Vol. I for details of procedures 

 used in determining grain sizes). The data reported are the RSA values, 

 not because these values are more reliable, but rather because all the data 

 in experiments 70X-06 and 70X-10 were reduced by this method. 



The collection of sediment samples was not included in the experimental 

 program until near the end of the 1970 experiments. As a result, no data 

 on the actual initial grain-size distribution exist. The RSA median grain 

 size of the sediment used, when well mixed at the beginning of the 1971 



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