246 MARK S. W. JEFFERSON 



the beach, now up, now down, but always along in some lateral 

 direction. In this form a short journey along the beach means 

 a much longer journey along the actual path of travel, and longer 

 opportunity for the attrition that comminutes all beach material. 



On any beach where cusps occur the waves may be seen scour- 

 ing out the bays and building fan cusps below. If it be asked 

 how this begins, the answer must be that the beginning is as old 

 as the beach. When first a ridge of cobbles was flung up by 

 the waves and seaweed driven upon it with the rising tide, there 

 came a moment when a great wave broke on the ridge crest to 

 send a rush of water further shoreward. This water escaping 

 guided the scouring of the first bays in the stony ridge. In 

 these the waves will continue to play, deepening the scour ways, 

 lengthening the delta cusps, and working over and modifying the 

 mass till another spring tide or another on-shore gale builds a 

 new barrier with stones and seaweed newly torn from the bottom, 

 Each set of cusps may modify its successors. A new crest of 

 seaweed flung up today is likely to have its weak points in some 

 measure determined by the previous channels. In violent storms 

 it is doubtful if this control is significant. Each storm probably 

 sets the shape in which the waves must play for a long time. 



As these studies have been made at a single beach, though 

 confirmed by some observations from Gay Head and Narragan- 

 sett Bay, corroboration or modification of the interpretation by 

 others would be welcome. 



Mark S. W. Jefferson. 



