average rate o£ 0.018 foot (0.55 centimeter) per hour. After 205 hours 

 the bar was eroded, as indicated by the shoreward movement of the -0.3-, 

 -0.4-, and -0.5-foot contours in Figures 19, 20, and 21. The inner region 

 maintained a fairly steep slope from 220 to 375 hours (shown by the close 

 spacing of the -0.2-, -0.3-, -0.4-, and -0.5-foot contours in Figs. 19, 

 20, and 21). 



The movements of the -0.3- and -0.4- foot contours along the three 

 ranges are compared in Figure 22. No lateral variation apparently 

 occurred in the changes of the inner region, other than minor differences 

 in the bar crest elevation between and 200 hours (see the different 

 positions of the -0.3- foot contour in Fig. 22). 



(b) Outer Region (Experiment 71Y-06) . Although some deposi- 

 tion occurred during the first 2 hours which moved the -0.6-, -0.7-, and 

 -0.8-foot contours 1 foot in the seaward direction, the outer region 

 remained unchanged for 175 hours. After 175 hours the -0.7- and -0.8-foot 

 contours began moving in the seaward direction as material was deposited 

 at the seaward edge of the inshore zone, and the -0.6-foot contour began 

 moving in the shoreward direction as erosion of the bar began in the inner 

 region. After 200 hours the outer region became a long, relatively flat 

 shelf, as shown by the divergence of the -0.8- and -0.5-foot contours. 



The several intercepts of the -0.6- and -0.7- foot contours indicate 

 several small bars and troughs. Figure 23 shows the appropriate contour 

 intercepts connected and the bars and troughs indicated by shaded areas. 



The length of the shelf continued to increase as material eroded from 

 the foreshore and was deposited offshore. The largest fluctuations in 

 contour position were two temporary shifts of about 10 and 12 feet in 

 the -0.7-foot contour position (Figs. 19, 20, and 21). The same shifts 

 occurred simultaneously at all three surveyed ranges (Fig. 22), showing 

 that this change was two-dimensional, and suggesting that significant net 

 sand transport occurred across the inshore zone during these periods. The 

 large shifts in the -0.7- foot contour represent an increase in the depth 

 over the inshore zone. 



The -0.6-, -0.7-, and -0.8-foot contours indicate no significant 

 lateral variations (Fig. 22). The variations in the -0.6-foot contour 

 show that the bar crest elevation reached -0.6 foot at different times 

 along the different ranges. 



(c) Inner Region (Experiment 71Y-10) . Contour movement in 

 the inshore zone along the five ranges for experiment 71Y-10 is shown in 

 Figures 24 to 28. Movements of the seawardmost intercepts along ranges 

 1, 3, 5, 7, and 9 are compared at depths of -0.3, -0.4, -0.6, -0.7, and 

 -0.8 foot in Figure 29. 



Within the first 10 minutes a longshore bar formed at station +4. The 

 bar remained stationary for the first 100 hours, while the crest elevation 

 varied between -0.3 and -0.4 foot, as shown by the movement of the -0.3- 

 foot contour in Figure 29. Erosion of the longshore bar began first along 



54 



