LITERATURE OF THE SUBJECT 601 



the tongue and excavating the bottom of the bay still further. As the re- 

 entrant grows larger and the tide rises higher, the water, as it runs up, forms 

 a small wave, which breaks on the shore of the recess and casts the pebbles 

 more into the form of a ridge. This action, continuing for some hours before 

 the tide turns, serves to shape the embayment. 



"It should be carefully noted that, when the swaying waters rush up into 

 the shore scallops, the converging walls of these indentations deepen the cur- 

 rent and add to the efficiency of its movements — a process which is essentially 

 like that which is brought about when an ordinary wave enters into a recess 

 of the clift, or the tidal undulation is crowded into an indentation such as the 

 Bay of Fundy." 



In his paper, "Sea-beaches and Sand-banks" (1898), Vanghan Cor- 

 nish briefly refers to the "succession of ridge and furrow at right angles 

 to the sea-front," and attributes the phenomenon to the erosive action of 

 waves which are increasing in size and attempting to reduce the beach 

 slope to a gentler gradient (637). 



One year later (1899) Prof. M. S. W. Jefferson published a paper in 

 which he described some of the characteristic features of beach cusps and 

 offered an explanation of their origin. Jefferson's studies were "made 

 at a single beach (Lynn Beach), though confirmed by some observations 

 from Gay Head and Narragansett Bay." He concluded that the cusps 

 were caused by the escape of water from behind a barrier of seaweed 

 located near the upper zone of the beach. Occasional waves of more 

 than average size overtop the seaweed barrier and leave large quantities 

 of water imprisoned behind it. After the retreat of the wave the im- 

 prisoned water escapes through occasional breaches in the barrier and 

 flows down the beach in streams of considerable strength, which scour 

 away the beach material along their courses. The residual masses of 

 material thus left between the stream lines are gradually shaped by the 

 waves into typical beach cusps. A stony barrier would probably not 

 operate in the same manner as a barrier of seaweed, since the water would 

 filter through the mass rather than wear channels. "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." 



In 1900 Prof. J. C. Branner published a paper entitled "The Origin 

 of Beach Cusps," based on observations made on the California coast and 

 the northeast coast of Brazil. He noted the fact that cusps occur where 

 "there are no seaweeds or other '^drift' on the beach," and concluded that 

 they are formed "by the interference of two sets of waves of translation 

 upon the beach." The accompanying diagrams, reproduced from Bran- 

 ner's paper, will serve to make his theory clear. In figure 1 "the con- 

 centric lines represent two sets of waves advancing on the beach in the 



