CHARACTERISTICS 607 



There is no necessary relation between the size of the cusp and the size of 

 the material of which it is composed. Large cusps built wholly of fine 

 sand are reported from Virginia Beach, and still larger ones (20 to 30 

 feet from apex to base and 75 to 90 feet between apices) built of similar 

 material were observed on the beach south of Dyker Heights. The largest 

 examples are more often built of coarse gravel or cobblestones, while 

 small ones may be composed of either fine sand or coarse gravel. The 

 very smallest cusps (a few inches in length) consist of fine material only, 

 since the small waves which build them can not transport coarse gravel 

 or cobblestones. Where both coarse and fine materials occur on a beach, 

 the cusps are built of the coarse material. Gravel cusps on a sandy 

 beach are of common occurrence, but I have not observed sand cusps on a 

 gravel beach. 



SIZE 



The smallest cusps which have come under my obesrvation have been 

 those artificially produced in the laboratory. These have varied from an 

 inch to several inches in length, measured from apex to base. Some 

 almost as small are to be found along the shores of sheltered ponds. On 

 a sandy beach at the head of a protected bay south of Huletts Landing, 

 Lake George, cusps from 8 to 12 inches long were formed by the small 

 waves set in motion by a gentle breeze. Those found along the seashore 

 may reach a length of 30 feet or more. It should be noted, however, 

 that the length measured from apex to base is less significant than the 

 distance between cusps, measured from apex to apex; for while it is a 

 general rule that the farther apart the cusps the larger is their size, some 

 which are closely spaced may be greatly elongated, as pointed out above, 

 and this elongation appears to be the result of rather accidental condi- 

 tions, and to have no great significance. Measurements across the bases 

 might be more significant, but it is often difficult to determine the length 

 of base, as when the cusps form part of a beach ridge or constitute widely 

 separated heaps of gravel having a vague shoreward boundary. However, 

 enough has been said to give some idea of the range in size ; and although 

 size is in some degree related to spacing, the latter is the really important 

 factor, as noted below. 



SPACING 



The very small cusps made in the laboratory are from one to several 

 inches apart, measured from apex to apex. On the shores of small ponds, 

 bays, etcetera, where only small waves are developed, the spacing varies 

 from less than a foot to two feet or more. On sea beaches the cusps built 



