made through 28 September 1968, with patterns very similar to the pattern 

 depicted by data collected in the morning of 26 September (Figure 12) . 

 On 28 September, a second line injection was made about 1,200 feet 

 (635 meters) south. This line was about 672 feet (205 meters) long. 

 Surveys following the second injection never positively identified the 

 injection, although tagged sand was still identifiable at the site of 

 the first injection, probably because of burial. It is assumed that 

 sand injected during the second operation was rapidly transported down- 

 coast (south) and dispersed below detectable limits. Littoral transport 

 is summarized in Figure 13. Sea and swell are summarized in Figure 14. 



Short cores of sediment were obtained along the injection range 

 on 25, 26, and 28 September 1968 at varying elevations, but always one 

 sample at mean lower low water. On 28 September, cores were also ob- 

 tained 50 feet (15.2 meters) north and south of the first injection 

 line (Range 158) and along the second injection range (300 feet north 

 of Range 159). Samples were removed from the cores at 2-inch intervals, 

 and counts made. The energy spectrum was displayed during the counting 

 operation to ensure that xenon was present, especially where counts were 

 only slightly above background. Some of these data are depicted in 

 Figure 15 which clearly indicates burial of tagged sand. 



3. Results of Xenon Experiment 



Patterns of sediment dispersal and burial depicted in Figures 

 11, 12, and 15 make conclusions concerning sediment movement tenuous, 

 particularly since a count-rate balance is lacking. Based on the 

 approach of Bagnold (1947) and the ambient ocean waves and currents 

 (summarized in Figures 12 and 13) , the tagged sediment was expected to 

 move a considerable distance downcoast. But dispersal patterns indi- 

 cated only slight downcoast movement. Core data indicate burial, yet 

 intuitively, nearly total burial seems untenable. An alternative pos- 

 sibility is that movement of the tagged sand occurs, but in a manner 

 whereby the particles stream off in a random pattern at a random rate. 

 If this is the case, it is entirely possible that the streaming rate, 

 coupled with the low specific activity level of the xenonated sand, 

 moves particles downcoast at a rate below the level of detectability 

 of the system. 



The experiment in the CERC Shore Processes Test Basin (SPTB) in 

 1968 indicated that a small quantity of high specific activity xenonated 

 sand would produce dispersal patterns similar to those of a larger quan- 

 tity of low specific activity xenonated sand. Therefore, the subsequent 

 field experiment with gold-tagged sand - analogous to the high specific 

 activity xenon sand in the laboratory experiment - should provide some 

 insight into the reason for the observed xenon patterns. Assuming burial 

 of the sediment or no movement of the sediment, then the gold-tagged sand 

 should describe the same (or closely similar) pattern as that depicted 

 by the xenonated sand. Conversely, if movement of xenon-tagged sand 



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