STABILITY OF THE ATLANTIC COAST 741 



Dr. J. W. Spencer: In support of the present stabilit:s' of the land and sea, 

 I have found from analysis of the daily fiuctuation of the Great Lakes that 

 there has been no change of even a tenth of an inch since 1850-1855. (See 

 chapter xxxi and appendix, "The Falls of Niagara," Geological Survey of Can- 

 ada, 1907.) 



Prof. A. C. Lane referred to the work of J. R. Freeman for the Charles 

 River Commission and since, and said that his observation of the Nantasket 

 region referred to led him to believe a subsidence of 5 feet between the for- 

 mation of the first connecting beach and the present might be allowed. 



Dr. H. B. Kummel: Since the results of Professor .Johnson's observations 

 have come to my attention I have been very much interested in determining 

 the origin of the unqualified assertion so frequently seen in text-books, that the 

 coast of New Jersey is subsiding at the rate of 2 feet per century. I found 

 that in 1857 Prof. George H. Cook, then professor of geology at Rutgers Col- 

 lege, New Brunswick. New Jersey, read a pai^er before the American Asso- 

 ciation for the Advancement of Science, in which he set forth the various 

 facts which led him to conclude that the coast of New Jersey had suffered a 

 long-continued and slow subsidence, and that this dowuAvard movement was 

 still in progress. At the close of his paper he cited a number of facts bear- 

 ing on the rate of subsidence, and he concluded that "we may, with some 

 degree of probability, state the average subsidence in the district where the 

 observations were made as two feet in a century." Referring to facts in 

 relation to the rate of subsidence, his final statement was, "It is not unlikely 

 that other and more numerous observations may give a different result." 



On the basis of this paper, published in the American Journal of Science in 

 November, 1857, the present subsidence of the New Jersey coast at the rate 

 of 2 feet per centuiy was apparently accepted as demonstrated, and state- 

 ments to that effect were published thereafter in Dana's Manual of Geology, 

 at first on the authority of Professor Cook, and later without authority, as a 

 well known and established fact. 



In 1885, in the report of the State Geologist of New Jersey for that year. 

 Professor Cook reviewed all the data in his possession bearing on changes 

 along the New Jersey coast, and while he still held the opinion that the coast 

 was sinking, he stated that it was "at a rate which is not yet quite definitely 

 established." 



Two or three years later, after the topographical survey of the State was 

 completed, certain facts in regard to the relative level of high tide in the 

 ocean and in the lagoons behind the barrier beaches were brought to Pro- 

 fessor Cook's attention, and he then realized that some of the facts upon 

 which he had very stronglj^ relied as proving present subsidence were prob- 

 ably to be differently interpreted; so that I think I am safe in saying that at 

 the time of his death, in 1889, he was not nearly so strongly convinced that 

 the coast of New Jersey is sinking at the present time as he was thirty years 

 earlier. 



Professor Johnson replied as follows : Referring to Mr. Spencer's com- 

 ments, I might say that it was the intention of Mr. J. B. Tyrrell, had he not 

 been compelled to leave early, to present certain evidence recently acquired 



