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THE 



AMERICAN JOURNAL OF SCIENCE 



[THIRD SERIES.] 



Art. LIT. — Long Island Sound in the Quaternary Era, 

 ivith observations on the Submarine Hudson River Chan- 

 nel ; by James D. Dana. "With a map, Plate X. 



The charts of the U. S. Coast and Geodetic Survey have 

 made Long Island Sound and the Atlantic border a means of 

 geological instruction in many ways. The recent issue by 

 the Survey after new soundings, of a chart which admits of 

 convenient photographic reduction, has afforded me the oppor- 

 tunity to illustrate with a map" some conclusions which I 

 deduced from them many years since ; and I now take advan- 

 tage of it in order to sustain or modify the views before 

 presented as the new facts may seem to require. The subjects 

 are : first, The Condition of Long Island Sound in the Glacial 

 period ; secondly, The Origin of the channel over the sub- 

 merged Atlantic border attributed to the flow of the Hudson 

 River during a time of emergence. 



* This map is reduced one-half from the Coast Survey Chart No. 8a, 

 entitled "Approaches to New York : Block Island to Cape May; from surveys 

 of 1878 to 1883." The omissions are a southern portion of the chart, the Light- 

 houses and the information to Navigators on the margin. The additions are 

 Cotidal lines for the Sound, taken from a map published by Prof. Bache, Super- 

 intendent of the Coast Survey, in the Report for 1854, and inscribed as prepared 

 by C. A. Schott, of the Coast Survey, from observations by Lieuts. C. H. Davis, 

 and J. R. Goldsborough, U. S. A. ; additional bathymetric lines for the Sound, 

 and a strengthening of those over the Atlantic border to make them more readily 

 appreciated ; and a few soundings from the larger charts of the Sound and of New 

 York Harbor. The larger charts of the Sound are three in number (Nos. 11-4, 

 115, 116), the scale pf 00 -. (They will be found to be of gr^at value in the class 

 room for geological illustration of tidal and sea-shore action.) 



The soundings on the map show the depth at mean low tide in fathoms up to 

 3 fathoms, and in the shallower dotted portion in feet. 



Am. Jour. Sci. — Third Series, Vol. XL, No. 240.— Dec, 1890. 

 27 



