118 a study of the cow bay beaches. d. s. mcintosh. 



Conclusions. 



The Cow Bay beaches were the result of wave erosion 

 influenced bj^ littoral currents operating upon the glacial 

 material of islands and hills in and around the bay. The 

 process was mainly that of lateral tying. Until the drumlin 

 islands were consumed the beach retreated; afterwards, it 

 grew seaward. The age of the oldest beach is not less than 

 a hundred and fifty years or thereabouts, however much 

 older it may be. 



In connexion with old beaches, there naturally arises 

 the question of elevation or subsidence of the shore-line. 

 The subject is one that has, during the last few years, received 

 a good deal of attention. The statement that the north- 

 eastern coast of North America is at present sinking at the 

 rate of about one foot per century has been disputed. 

 Detailed work has recently been done in several places 

 along this coast, and Dr. Douglas W. Johnson, in an interesting 

 paper, ^shows that much evidence that has been adduced in 

 support of elevation and of subsidence can be otherwise 

 explained. From his study of the Nantasket area, in col- 

 laboration with Mr. W. G. Reed Jr., the conclusion is reached 

 that ''no marked changes in the relative position of land and 

 sea have occurred in that locality during the last thousand 

 years at least." 



In the Cow Bay area, there appears to be no evidence that 

 necessarily points to elevation of the coast-line. The grassed 

 cliff on the partly eroded drumlin A, with its shelving beach, 

 is the result of wave erosion succeeded by prograding of the 

 beach brought about by the accumulation of the abundant 

 material driven in from Osborne head. The highest old 

 beach is the work of a heavy storm. The evidence is strong 

 in favor of this explanation. This b3ach is, moreover, 

 not higher than the high modern storm beach at the western 



1. Douglas W. Johnson, Fixite de la Cote AllaiUique de V Amerique du Mord (Annalei de 

 06oj£raphie, tome XXI, 1912, pp. 193-212). 



