168 E. C. ANDREWS. 



been scalloped and the strand at the tiny indentation to 

 the immediate north never appears to have been scalloped. 

 Nevertheless, thence to the north the cusps were very 

 prominent, but at another point almost in the central por- 

 tion of the northern or main arc of the beach, a space about 

 150 to 200 yards in length was cuspless, whereas north and 

 south of this length of smooth beach the cusps might be 

 traced gradually through insignificant markings to deep 

 and well-spaced examples. 



During the seven years of observation it was noted also, 

 in periods of offshore winds, that the breaking waves or 

 wavelets generated whole series of interfering circles or 

 curves which travelled up the beach in geometrical pat- 

 terns. These patterns were similar to those produced on 

 a smooth pond by throwing stones into it simultaneously 

 at regularly-spaced intervals along a line or zone. It was 

 noted in every case that the interfering circular or curved 

 ridges and troughs were larger and higher in proportion to 

 the height of the breaking wave. 



It was considered finally that the breaking wave might 

 be considered as a number of unit columns of falling water, 

 which were urged or impelled onward again by the unex- 

 pended energy of the wave portion which had not actually 

 broken. In proportion to the height and volume of the 

 breaking wave, so would be the energy of the interferences 

 between the falling or cascading columns of water, and 

 these would arrange themselves into regularly-spaced 

 interferences of major importance as in the case of other 

 varieties of rhythmical interference. In this particular 

 case the major interferences bore a definite and simple 

 relation to the strength of the fall of the unit columns or 

 sections of the breaking and advancing wave, and these 

 main interference figures were expressed on the beach as 

 erosion and accumulation forms. From the salients, the 

 sets were spaced with intermediate nodes of smooth beach. 



