From the evidence presented in the previous paragraphs, it is concluded 

 that (1) updrift sediments did not become significantly "coarser" during this 

 study and (2) there was no significant updrift buildup of sediments. Rather, 

 sediments were transported downdrift into the trap as a series of pulses or 

 "waves," and transport conditions were such that all sizes available were 

 transportable into the trap, even into its deepest reaches. 



3. Coring and "Envelope ." 



From the two previous sections it appears that for this study, cored samples 

 did not accurately describe the texture of native beach sands since the cored 

 composite was coarser and more poorly sorted than all other composite estimates. 

 These differences imply that either the criteria used to define the cored 

 envelope or the coring and sampling procedures themselves may be suspect as a 

 means for describing beach sediments. There is no doubt here that all sediments 

 cored were recovered and sampled and that there were no losses or gains to con- 

 taminate the samples. Since the samples appeared representative, the coring 

 criteria were examined. 



Elevation maximums and minimums were used to define the active profile 

 envelope and, as discussed earlier, sediments contained within the envelope, 

 as cored, represented both storm (coarse) and nonstorm (finer) deposits; the 

 interlayering of these two sediment populations was most pronounced at 

 shallower water depths within the nearshore zone. Elevation maximums and mini- 

 mums were also greatest at shallower nearshore depths. Figure 9 shows some of 

 these sedimentary relationships for core segments taken from the native beach 

 and segments from the trap. 



For the native beach, sediments are much coarser inshore (Fig. 9, core 23) 

 than offshore (core 25) . There are few individually identifiable layers within 

 the offshore core and grain sizes are nearly alike, whereas the inshore core 

 is characterized by alternating coarse- and fine-grained layers of varying 

 thickness. In addition, coarse-grained layers commonly fine or grade upward 

 within a layer (core 23) indicating a gradual waning of depositional energy. 

 Graded layers like these typify storm deposits where coarse sands and gravels 

 are overlain by successively finer sands deposited as the storm abates. Inter- 

 spersed between the stoirm layers are finer layers representing normal nonstorm 

 deposition. Scour depths would depend on the intensity of a specific storm; 

 thus, the active profile envelope at any particular mom.ent could contain one 

 or more graded storm layers as well as a variable number of nonstorm layers. 

 The offshore profile would also be affected by storms, but both textural vari- 

 ations and the thickness of the profile envelope would be smaller offshore than 

 closer inshore because the energy conditions themselves vary less at greater 

 water depths. As a result of these relationships, nearshore deposits within 

 the active profile are both the thickest and the most variable, and thus can 

 significantly affect composite textural calculations. Coring during one day 

 might result in a fine, well-sorted composite whereas another day's composite 

 might be much coarser. Since the purpose of a composite is to describe an 

 average sediment population, the unpredictability associated with coring the 

 active profile envelope makes this an unsatisfactory sampling approach. 



Cores taken in the sand trap are quite similar for each water depth to 

 those from the native profile (e.g.. Fig. 9, core 5 versus core 23, core 7 

 versus core 25). The offshore sediments (core 7) are well sorted and nearly 



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