Febbuaby 24, 1911] 



SCIENCE 



301 



halt; or they might be explained as the result 

 of local fluctuations of marsh level or of tide 

 level, independent of a downward movement 

 of the coastal region. The long halt in the 

 supposed downward movement seemed to be 

 demanded by the physiographic evidence. 



Observations in the Scituate-Marshfield 

 region revealed a cause of fluctuations in 

 high tide level which appeared competent to 

 explain most, if not all, of the evidences of 

 recent subsidence. After a consideration of 

 the tidal conditions along the Atlantic coast, 

 and a study of the nature of the high tide 

 surface about the coasts of England, as re- 

 ported by Wheeler and others, the conclusion 

 was reached that the conditions in the Sci- 

 tuate region had been repeated in a greater or 

 less degree all along our coasts in recent geo- 

 logical times, as a necessary consequence of 

 the nature of the high tide surface and the 

 changes efl'ected by wave action on all shores, 

 particularly those composed of poorly consoli- 

 dated materials. The cause seemed competent 

 to explain a deposit of peat varying in thick- 

 ness from a few inches to a possible maximum 

 of 15 feet or more, according to the former 

 range of the tides. As all of the supposed 

 evidence of recent subsidence on the Massa- 

 chusetts and New Jersey coasts are, so far as 

 known to the writer, capable of explanation 

 on the basis of a fluctuating high tide surface, 

 and as the conditions on those coasts make 

 such fluctuations in the past a seeming neces- 

 sity; and as the physiographic evidence, on 

 the Massachusetts coast at least, points to a 

 long period of coastal stability in recent times, 

 the conclusion seems reasonable that, while 

 subsidence in the past may have occurred, the 

 evidence of recent subsidence in these two 

 areas is not decisive. Further study convinces 

 me of the correctness of that conclusion. But 

 whether it is correct or not, it was not reached 

 with undue haste, nor was the botanical evi- 

 dence of subsidence " lightly disregarded." 



When a problem that has been discussed for 

 many years, on the supposition that it in- 

 volves but X factors, is found really to involve 

 3>-\-l factors, all of the earlier conclusions 

 should be carefully reconsidered; not that they 



are necessarily wrong, but because it can not 

 be known that they are right until the addi- 

 tional factor is fully considered along with 

 the others. The problem of recent subsidence 

 of the Atlantic coast has long been discussed ; 

 but the importance of a high tide surface 

 which fluctuates with changes in the form of 

 the shoreline, as a possible explanation of this 

 apparent subsidence, does not appear to have 

 been considered in the published discussions 

 of the problem. It is an element of possible 

 value in all cases of tidal shores which are ir- 

 regular in outline or which are bordered by 

 barrier beaches. Hence all conclusions which 

 have been reached in regard to recent subsi- 

 dence in such cases ought to be revised in 

 order to take this element into account. What 

 the result of revision in each case will be can 

 not be foretold; and for this very reason the 

 revision seems the more necessary. The writer 

 is attempting such a revision for several lo- 

 calities, without prejudice in favor of any par- 

 ticular conclusion, and in most of the eases 

 without any idea as to what the final result 

 will be. 



My statement as to the inconclusiveness of 

 the evidence of recent subsidence on the Mas- 

 sachusetts and New Jersey coasts, was made 

 after a careful reading of Mr. Bartlett's very 

 interesting paper on the sub-marine Chamcecy- 

 paris bog at Woods Hole, Mass. Although 

 this paper presented a most ingenious and in- 

 teresting argument in favor of recent sub- 

 sidence, the validity of the argument depended 

 upon certain assumptions which seem to me 

 untenable. It was not the object of my brief 

 paper to discuss the voluminous evidence in 

 favor of recent subsidence, but rather to make 

 a short preliminary announcement of an 

 hypothesis which appeared to be of consider- 

 able importance ; for this reason I did not deal 

 specifically with Mr. Bartlett's observations. 

 Full attention will be given to all accessible 

 evidence in favor of recent subsidence in a 

 future publication. 



A careful reading of Mr. Bartlett's criticism 

 of my paper leads me to think that he has 

 1 failed to discriminate sufiiciently between low- 

 lying peat deposits which may be of consid- 



