FORM OF NANTASKET BEACH. 187 



area. Hereafter the normal development of the beach, unless arrested, 

 would result in decreasing its area. 



CHANGES OF LEVEL IN THE NANTASKET AREA 



Much has been written concerning possible elevations and depres- 

 sions of the Massachusetts coast since the glacial epoch. The evi- 

 dence is often unsatisfactory and contradictory, but is thought by 

 many to indicate a gradual subsidence at the rate of approximately 

 one foot in one hundred years. Professor Crosby believes that some 

 of the drumlins, which now show no marked cliffs facing toward the 

 Atlantic, were strongly cliffed before Nantasket Beach was com- 

 pleted, and that subsidence has carried these cliffs under water. 

 "This view relieves us of the necessity of imagining a cordon of 

 drumlins outside of the present beach which have been completely 

 washed away, although it is not improbable that Harding's Ledge 

 and the Black Rock Islets are the foundations of such vanished 

 drumlins" (Crosby, p. 170). As we have shown above, there is 

 abundant evidence that a number of drumlins did formerly exist out- 

 side of the present beach, and that these drumlins and their associated 

 bars and spits effectively protected drumlins back of them from 

 erosion. No subsidence is required to account for the lack of clifSng 

 on the eastern ends of drumlins back of the present beach, and no 

 evidence of submerged marine cliffs has ever been found. 



It seems to us quite possible that there may have been a con- 

 siderable depression in the Boston region since the glacial epoch; 

 and that there may have been a very recent depression of small amount 

 at the calculated rate of one foot in one hundred years. But that 

 there has been any marked change in the relative position of land and 

 sea during the last thousand years or more seems to us absolutely 

 incompatible with the evidence furnished by Nantasket Beach. 

 West Beach, as has already been pointed out, is similar in size and 

 elevation to the beaches being formed along the present eastern 

 shore of the Nantasket area. Had there been marked depression 

 since the formation of West Beach, that beach would now be very low, 

 possibly completely submerged. Had marked elevation occurred, 

 West Beach should be relatively high, and other evidences of elevation 

 should appear along the western margin of this beach. The close 



