[c) Inner Region (Experiment 70X-10) . The inshore zone in 

 the 10-foot tank developed in a pattern similar to that in the 6-foot tank, 

 but at a different rate of change. Contour movement in the inshore along 

 the five ranges for experiment 70X-10 is shown in Figures 26 to 30; the 

 movement of selected individual depths along the five ranges is compared 



in Figure 31. 



Within the first 10 minutes of testing a longshore bar formed at sta- 

 tion 4 by plunging breakers. After 10 hours the bar position stabilized 

 at station 3, with the elevation of the crest varying from -0.3 to -0.4 

 foot, as shown by the shifting of the -0.3-foot contour (see Figs. 26 to 

 30). At 56 hours the bar began to disappear and was completely eroded 

 by 90 hours, as evidenced by the movement of the -0.4-foot contour inter- 

 cepts in the figures. 



Between 70 and 94 hours the inner inshore region was eroded, and from 

 94 to 160 hours this region had a fairly stable slope. After 160 hours 

 the inner inshore along ranges 1 and 3 steepened (Figs. 26 and 27) and 

 along ranges 5, 7, and 9 was stable (Figs. 28, 29, and 30). 



The movement of the seawardmost contour intercepts for -0.2 and -0.4 

 foot is compared in Figure 31, The lateral variation in changes of the 

 inner inshore is exhibited particularly at the 0.4-foot depth. The ero- 

 sion of the bar began sooner along ranges 1 and 3 than along range 5, and 

 much later along ranges 7 and 9, 



(d) Outer Region (Experiment 70X-10) . During the first 14 

 hours of testing little significant change occurred in the outer region, 

 only slight erosion at 0.5- and 0.6-foot depths as a result of formation 



of the bar in the inner region. After 14 hours the -0.8-foot contour began 

 moving seaward as a result of the deposition offshore. After 36 hours the 

 -0.5-foot contour moved shoreward as the inner inshore was eroded. From 

 56 to 94 hours the shorewardmost -0.6-foot contours (see Figs. 26 to 30) 

 moved shoreward creating the wide outer region. There was no significant 

 lateral variation in the movement of the seaward edge of the outer region 

 (-0.8-foot contours in Fig. 31). However, a significant lateral variation 

 occurred in the depth of the outer region. The movements of the -0.6- and 

 -0.7-foot contours (Fig. 31) partially indicate the variation--the depth 

 over this shelf increased from range 1 to range 9. The depths along range 

 1 (Fig. 26) varied between 0.6 and 0.7 foot, along range 3 (Fig. 27) was 

 generally 0.7 foot and occasionally 0.6 foot, along range 5 (Fig. 28) was 

 0.7 to 0.8 foot (twice reached a depth of 0.6 foot), along range 7 (Fig. 

 29) varied between 0.7 and 0.8 foot, and along range 9 (Fig. 30) varied 

 between 0.7 and 0.9 foot. 



(3) Offshore Zone . The offshore zone was essentially a zone of 

 deposition. Initially, the deposited material formed a steeper slope in 

 this zone and later the zone prograded seaward as more material was 

 deposited. 



55 



