fiQUtVOCAL FEATtTRES — ABSEiNCB OF BEACHES 299 



Equivocal Features 

 absence of beaches 



The one negative point, and the only one effectively used against the 

 suggestion of marine origin of the sand-plain and of other similar plains 

 in New England, is the absence of unequivocal, distinct beach phenomena 

 on the plains. The necessity for beaches has been tacitly assumed. It 

 will be shown that this assumption is wrong. 



Dr. F. J. H. MerrilP is the only student of the subject who has dis- 

 cussed this point. He showed a clear appreciation of the problem and 

 gave good explanation of the absence of beaches. The following quota- 

 tions are from Merrill's paper (11, pages 105-109) : 



"On Staten Island and western Long Island alluvial plains of stratified 

 material rise gently from the ocean shore to the margin of the moraine, ter- 

 minating at an altitude of about 80 feet, and although no continuous shoreline 

 is to be found, the plains are referred provisionally to the same period as the 

 estuary deposits a few miles north. 



"The records of ocean wave action are in many cases different from those 

 of the extinct quaternary lakes and not so easy to recognize. It is not always 

 possible to decide a question of submergence by the presence or absence of a 

 distinct shoreline. On a lake shore wave action tends to cut in an horizontal 

 plane, and the result is a series of terraces or a beach plane associated with 

 shore drift and littoral deposits in various phases. When ocean waves act on 

 a shoreline there may be two cases : 



"1. The land may be at rest. In this case the result will be the same as on 

 the shore of a lake which, maintains its level for a comparatively long time. 



"2. The land may be rising or subsiding with respect to sealevel. In this 

 case the plane of erosion will be a resultant of two planar forces: A, the 

 wave force which operates in an horizontal plane; B, the force of elevation or 

 depression which acts in a vertical plane." . . . 



After discussion of the effects of the interaction of the two forces, he 

 concludes his analysis of the mechanics of beach cutting as follows : 



". . . for the present purpose, which is simply to point out the fact that a 

 land surface in process of subsidence or emergence may be subjected to wave 

 action without being incised with distinct shorelines, and also that wave 

 action may produce an inclined plane as well as a terrace or lyaselemel. 



"It is therefore evident that submergence would not leave a deeply cut 

 shoreline as its record unless the rates of land movement were so adjusted as 

 to permit of it. In fact, no very distinctly cut shorelines are to be found on 

 the drift about New York, even at an altitude corresponding with that of the 

 Hudson estuary deposits. Apart from the still-water deposits the 80-foot post- 

 glacial depression about New York can only be traced by change of surface 



2 While this article is in preparation Doctor Merrill has passed away. The writer 

 regrets that he has not lived to see the verification of his theory. 



