1 68 D. W. JOHNSON AND W. G. REED, JR. 



it should be regarded as lateral tying, the connecting bar being built 

 at right angles to the direction of wave attack, and parallel to the 

 shoreline. Lateral tying similar to that represented by d and e, 

 Fig. 2, might be produced if the character of the sea bottom caused 

 the waves to break along the line de instead of entering the bay to the 

 points b and c; also in case a barrier beach migrating toward the shore 

 encountered the island and headlands in its progress. 



If several islands instead of one were involved in the foregoing cases, 

 more complex types of backward and lateral tying would result. 

 Nantasket Beach represents a complicated case of both lateral and 

 backward tying, involving for the most part prograded lateral tying 

 bars of the types b and c, Fig. 2, 



THE PRESENT FORM OF NANTASKET BEACH 



The principal topographic features of Nantasket Beach are shown 

 on the accompanying map (Fig. 8) based on a chart of Boston Harbor 

 prepared by the United States Coast and Geodetic Survey (No. 246, 

 C. & G. S. Boston Harbor, 1907). The larger features appear on the 

 chart, but we have added the details of smaller beaches, wave-cut 

 cliffs, etc. The irregular hills in the southern part of the map are 

 composed of much altered sedimentary and igneous rocks which 

 are very resistant and yield but slowly to the attack of the waves and 

 weather. All other elevations on the map represented by contours 

 are drumlins more or less eroded by wave action. The lower areas, 

 including the lower ridges indicated by short hachures, are practically 

 all of beach material; the exceptions consist of low areas of till between 

 certain drumlins located close to each other, beach sand gathered into 

 small dunes by the wind, and some deposits in swampy areas to be 

 considered later. If we except the rock above mentioned, we may 

 properly say that the features of the Nantasket region are due to 

 marine action upon drumlins; for the effects of stream action and 

 wind action are so slight as to be negligible. 



The drumlins.- — In describing the present form of the Nantasket 

 drumlins it will be convenient to consider them in the order of their 

 preservation from marine erosion. The letters in parentheses refer 

 to the respective drumlins on the map, Fig. 8. The best preserved 

 of the Nantasket drumlins is a small one called Hampton Hill (H), 



