CUSP A TE FORELANDS AT BAY OF Q UINTE I 2 5 



part passes the free end with little retardation. The result will 

 be a tendency for the material moving down the slope with the 

 undertow, and up the slope with the advancing wave, to be 

 dropped at a symmetrically arranged series of points. The 

 obliquely moving waves also move debris along the shore in the 

 resultant longshore direction of the wave advance. 



The result of the combined action of these different factors 

 is that gradually a little bar is built out from the shore by which 

 the waves attempt to readjust the curvature of the shore line to 

 a curvature appropriate to their direction of advance. Because 

 of the nearly uniform spacing of the waves, these bars will begin 

 at a number of symmetrically arranged points. Because of the 

 normal, uniform slope of the subaqueous floor, the maximum 

 distance from shore at which the undertow can materially inter- 

 fere with the advance of the next wave will be located at a 

 nearly uniform distance off the initial shore line, and this will 

 tend to limit the size of the individual cusplets. The size is also 

 limited by the distance between the crests of the waves. The 

 building of the cusplets further modifies the form of the shore 

 line, the slope of the bottom, the direction of the advance of the 

 waves, and the direction of the longshore currents ; but with 

 waves of constant size an equilibrium will be established, at 

 which time the cusplets will have their maximum size. If the 

 waves are irregular, cusps may not be formed at all. 



The same waves which had built the serrate margin along 

 the eastern side of this foreland had built a small flying spit at 

 the apex. Between the free end of this small flying spit and 

 the main beach a very small A-shaped point was also gradually 

 built up. The waves coming from the east in the direction indi- 

 cated by the arrows (Fig. 10) swung around the point, giving it 

 the form shown in the figure. The fronts of the waves assumed 

 the form of a series of helicoidal curves as they swung around the 

 point as if on a pivot. As many as eight waves could be counted 

 swirling around the west end of the flying spit at the same time, 

 the moving crests looking not unlike the spokes of a gigantic 

 horizontally rotating wheel. The relative positions of the succes- 

 sive wave-fronts are shown by the dotted lines in the figure. 



