profile was 0.16 centimeter per centimeter. Since the beginning of 

 gradient measurements on 2 July, the ridge grew three-dimensional ly, 

 thereby offering more surface area or resistance to wave action as time 

 progressed. The result of a greater resistance to wave action was a 

 gradual steepening of the ridge gradient (Fig. 25). Calculations of 

 breaker power for this period revealed an increase between 7 and 9 July, 

 which also steepened the ridge gradient (Fig. 24). 



Other processes acting concurrently with the landward migration of 

 the ridge may also reshape or alter ridge and backshore morphology. The 

 aerial photo in Figure 13 shows a large runoff channel north of PL- 10. 

 A closeup photo of the channel (Fig. 21) reveals that upper flow regime 

 conditions often exist in these channels. The antidunes in this photo 

 have an amplitude of 8 to 10 centimeters and result in a noticeable 

 "calving" of the ridge with the returning flow of water from the runnel. 

 Scarps up to 30 centimeters high along the edges of runoff channels were 

 present throughout the study period. Returning flow from runnels may 

 also cause noticeable erosion at the base of the beach face (Fig. 26). 

 Runnel currents strong enough to erode the beach face are usually a 

 result of difference in elevation on an elevated runnel caused by a 

 nonsimultaneous welding of a ridge along the backshore. 



Although the changes in morphology in the large ridge area between 

 PL-0 and PL- 3 were more rapid than changes at other parts of the study 

 area, distinct morphological changes associated with less mature stages 

 of beach morphology were noticeable between PL-4 and PL- 10. The migra- 

 tion and subsequent welding of small ridges (amplitude <40 centimeters) 

 occurred on PL-9, PL- 10, and PL- 11 between 2 and 9 July (Fig. 27). Pro- 

 files PL-4 through PL-8 were sites of less active accretion during the 

 preweld phase. Beach face and ridge gradient changes at PL-6, a typical 

 early accretionary profile, revealed no steepening of the ridge gradient 

 as at PL-0 for the same time period (Fig. 24). The area between PL-4 

 and PL-8 remained the least mature part of the study area throughout the 

 summer period. Profiles PL-9 through PL- 11, initially at a less mature 

 stage of development than the area between PL-0 and PL-4, developed a 

 broad convex berm after a large ridge had welded onto the backshore. 



The transition between the early preweld period and the postweld 

 period at PL-0 is shown in Figures 28 and 29. In Figure 28, evidence of 

 the upper flow regime conditions on the ridge surface can be seen in the 

 form of plane beds with grain lineations. Previous high tide upper flow 

 regime plane beds are evident in the area of the slip face exposed below 

 the ridge surface. The numerous lobes of sediment extending into the 

 runnel are the result of late-stage erosion of the ridge surface as the 

 water level dropped below the crest of the ridge. The small lobe in the 

 center of Figure 28 is the area of the first weld within the study area 

 on 11 July (Fig. 29). As the time of complete welding of the ridge 

 approached, the active slip face diminished in amplitude, and on 12 

 July, the ridge completely welded to the backshore. At times the relict 

 form of the former runnel may remain for a period of several days after 



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