FORM OF NANTASKET BEACH 163 



Beach; and to Mr. F. M. Hersey of Boston, and the officials of the 

 United States Coast and Geodetic Survey for numerous courtesies. 

 In addition to these gentlemen, our thanks are due to many others in 

 Boston and Hull for various services. 



Nantasket Beach lies at the southeastern border of Boston Harbor, 

 separating that portion of the harbor from the Atlantic Ocean (Fig. i). 

 The name " Nantasket Beach" is generally applied to all of that irregu- 

 larly shaped lowland between the rocky hill of the Atlantic on the 

 south, and the drumlin known as Allerton Great Hill on the north, and 

 is not restricted to that portion of the lowland immediately bordering 

 the ocean at the present time. As thus defined Nantasket Beach has 

 a width of from a few hundred feet to more than half a mile, and a 

 length of a little more than three miles. In our discussion we include 

 the neighboring district of Hull, as well as several outlying islands, 

 which are more or less closely related to certain phases of our investi- 

 gation. 



THE PROBLEM STATED 



A casual study of the Nantasket district makes clear the fact that 

 Nantasket Beach consists of sand, gravel, and cobbles, deposited by 

 wave action between several drumlins which formerly existed as 

 islands. The problem which we have to consider may therefore be 

 described as a problem in island-tying by means of beaches. The 

 tying of islands to each other and to the mainland, by the formation of 

 connecting beaches, has been recognized as a common phenomenon 

 along a youthful shoreline of depression, where islands are apt to be 

 more or less numerous. Boston Harbor occurs on a shoreline of 

 depression, but the islands which help to form the harbor, and which 

 are frequently connected with each other and with the mainland by 

 beaches, do not as a rule represent the summits of hills left as islands 

 by the depression of a maturely dissected mainland. They are for 

 the most part typical drumlins, the trend of whose long axes indicates 

 that the ice-sheet which fashioned them moved from the land south- 

 eastward out to sea. It is evident that drumlin islands might be 

 formed along a shoreline of elevation; hence the phenomena about 

 to be described might occur along both of the standard types of shore- 

 lines. The principles involved in our discussion remain the same, 

 whether the islands be composed of solid rock or unconsolidated 



