In the inshore, little significant lateral variation occurred at 

 elevations -0.4, -0.5, and -0.6 foot; only a random variation in the 

 times at which the longshore bar crest reached elevation -0.3 foot 

 (Fig. 51). 



Large lateral variations occurred in position of particular contours 

 in the offshore (Fig. 52), indicating that the crest elevation of the 

 seaward bar reached -2.0 feet at different times, but the variations had 

 no pattern. 



At the end of the experiment the only significant lateral variation 

 was the slope of the foreshore (Fig. 53). 



d. 3.75-Second Wave . 



(1) L/W = 3.14 (Experiment 72A-10) . Experiment 72A-10 had a 

 longer wavelength in a wider tank than experiment 72B-06 discussed above, 

 with the result that the L/W ratio was nearly the same (3.14 versus 

 3.10). As expected, this experiment also had little significant lateral 

 variation. 



The foreshore slope was steeper along the middle ranges (3, 5, and 

 7), varying from 0.14 to 0.36 with an average of 0.20, and flatter along 

 the outside ranges (1 and 9), varying from 0.12 to 0.30 with an average 

 of 0.18. The shoreline position varied laterally during the first 25 

 hours as it prograded first along the outside ranges (Fig. 54). Between 

 30 and 50 hours the shoreline position also varied laterally. At other 

 times the shoreline position was quite uniform. 



The only lateral variations in the offshore zone were differences in 

 the bar-crest elevation along the different ranges (Fig. 55), but this 

 was a fairly minor variation in elevation. 



A contour map of the profile at the end of the experiment in Figure 

 56 shows how little the lateral variations were. 



(2) L/W = 5.23 (Experiment 72A-06) . In experiment 72A-06, with 

 the highest L/W value, the lateral variations in profile shape were 

 quite large, contrary to what was expected. 



In the foreshore, a strong counterclockwise circulation caused the 

 foreshore slope to be steeper (0.20) along range 5 and flatter (0.12) 

 along range 1, but only at 115 hours was there a large (1.3 feet) lateral 

 difference in shoreline position (Fig. 57). 



In the inner offshore zone, a clockwise circulation developed between 

 the antinodes in the foreshore and near station 18 during the first 70 

 hours, and then began disintegrating. The wavelength in this area was 

 approximately 24 feet (7.3 meters), or four times the tank width, which 

 suggests that the circulation was the result of some resonance unique to 

 a laboratory wave tank. This is apparently another special tank width 



99 



