i64 D. W. JOHNSON AND W. G. REED, JR. 



glacial till; but it will appear that the stages of shoreline development 

 are passed through more quickly, the wave-cut cliffs are more sym- 

 metrical, and the past conditions more easily reconstructed where 

 drumlin islands are involved, as in the Nantasket case. 



In the following pages we shall briefly review the principles of 

 shoreline development, and then describe in some detail the present 

 form of Nantasket Beach. On the basis of this description, and in 

 view of the principles of shoreline development, we shall endea\'or to 

 reconstruct the initial form of the Nantasket district. Still guided 

 by the principles of shoreline development, we shall next trace the 

 successive steps in the development of Nantasket Beach from the 

 initial form to the present form, with brief attention to the changes 

 which will probably occur in the future. It will appear that Nantasket 

 Beach is a very complicated example of island-tying, which illustrates 

 in a rem.arkable manner the fact that shorelines are the product of 

 systematic evolution according to definite physiographic laws. 



LITERATURE 



So far as we are aware, no detailed account of the physiography 

 of Nantasket has been published. Professor W. O. Crosby (1893) 

 has described the hard rock geology of the district just south of the 

 beach in great detail and has considered the beach and drumlins at 

 some length. He has also discussed the evidence of post-glacial 

 changes of level in the Nantasket area. Other references to the 

 district here described are found throughout the literature on the 

 Boston Basin, but are not of importance in the present dis- 

 cussion. 



In 1896 Professor W. M. Davis published a paper entitled "The 

 Outhne of Cape Cod," in which he discussed at some length the 

 principles of wave and current action, and applied these principles in 

 a study of the present form of Cape Cod and the past changes in the 

 outline of the cape. The principles set forth in Professor Davis' 

 essay are considered more fully on a later page. 



Dr. F. P. Gulliver in a paper on "Shorehne Topography" (1899) 

 has discussed at length various shore forms, including beaches which 

 connect islands with the mainland or with each other. To such 

 beaches he has applied the name "tombolo." Several types of 



