242 MARK S. W. JEFFERSON 



that a stony barrier might play a similar part on a beach where 

 seaweed was absent. Great waves would surmount the crest 

 and the water caught behind escape as best it might to the sea. 

 Low places would doubtless occur in the crest of the line and 

 some water flow over them. But it is to be expected that the 

 water would filter through the mass rather than wear channels, 

 owing to the greater specific gravity of the barrier. It is unlikely 

 that bays could be cut out in the stones under such circumstances. 

 It would seem to follow that such stony cusps are to be looked 

 for only on coasts where seaweed or some similar material is 

 abundantly thrown up. 



As the tide falls, presently the waves cease to surmount the 

 crest of the weed and each wave in receding discloses more and 

 more of the lower beach. It now becomes evident that the 

 scouring waters that have been rushing down the bays have 

 spread the gravel with which they are visibly loaded in a great 

 fan at the mouth of the bay, fairly underlying the wave-fan seen 

 in Fig. 3, outside the seaweed. It is a true fan delta built by 

 the stream where its waters are checked by the relatively stag- 

 nant waters outside. As these deltas are built out in front of 

 the bays it results that in this outer line of points bays occur 

 opposite the points of the inner stony promontories. This is at 

 once clear on the diagram (Fig. 2). Walking along the beach 

 at low tide the delta fans are seen nearest and are more in evidence 

 than the stony or original cusps above. These upper cusps may 

 well be called residual, as they are remnants of a continuous line 

 in which the bays have been scoured out here and there. At 

 Lynn the residual cusps are stony but that is not essential. 

 In Fig. 1, the whole material is apparently fine beach sand. 

 The seaweed that originated the form is here hardly visible but 

 enough is on hand to show that it occurs on the beach. Atten- 

 tion should be called here to the fact that seaweed shrinks 

 enormously on drying. I have made no measurements and 

 have no data at hand, but sugar-cane, with which I am familiar, 

 contains nearly three times as much juice as wood, and cane has 

 certainly more woody fiber than most seaweed. For this reason 



