604 D. W. JOHNSON BEACH CUSPS 



in which it was pointed out that cusps may be produced, both naturally 

 and artificially, by a single series of waves parallel to the beach, uninflu- 

 enced by seaweed or other accumulations. On the basis of further obser- 

 vations and experiments, the origin of beach cusps was again discussed 

 at a meeting of the geologists of the northeastern United States held in 

 New York, April, 1908. An abstract of this communication appeared 

 in Science the following October. 



Before considering theories of origin, it is desirable to set forth in 

 some detail the characteristic features of the cusps. 



Characteeistics of Beach Cusps 

 contributing- observers 



In order to secure careful observations of cusps under as great a variety 

 of conditions as possible an outline of the points concerning which infor- 

 mation seemed desirable was prepared and given to a number of friends, 

 who offered to record observations. In this way my work has been sup- 

 plemented by contributions from the following persons relating to the 

 localities mentioned: Prof. W. 0. Crosby, Nome Beach, Alaska; Prof. 

 A. W. Grabau, beach south of Dyker Heights, Brooklyn, New York; 

 Prof. H. W. Shimer, Winthrop Beach, near Boston; Mr. T. I. Eead> 

 E. M., Virginia Beach, Virginia; Mr. James T. Kemp, beach neai 

 Huletts Landing, Lake George, New York; Miss M. E. Blodgett (then a 

 student in geology at the Massachusetts Institute of Technology), Lynn 

 Nantasket, and other beaches in the vicinity of Boston. To all these my 

 thanks are rendered. My own observations have principally been made 

 on Marblehead Neck, Lynn, Eevere, Winthrop, and Nantasket beaches, 

 near Boston; Westquage Beach, Ehode Island; the beach south of Dyker 

 Heights, Brooklyn; several beaches near Hulett's Landing, Lake George, 

 New York; beaches along various small lakes and ponds, and the arti- 

 ficial beaches referred to below. 



Among the points specified on the blank forms prepared as guides to 

 the observation of beach cusps were the following: Locality; general 

 description of beach; length of cusps; distance between points of cusps; 

 size of cusp material; relative steepness of two sides of cusp; position of 

 cusp axis relative to shoreline ; slope of beach ; comparison between beach 

 material and cusp material; whether or not cusps were being fashioned 

 at time of observation; any evidence of long-shore current; height of 

 waves; evidence of more than one set of waves; whether or not waves 

 come in parallel to beach ; direction of wind ; stage of tide. 



