Dana — Long Island Sound in the Quaternary Era. 431 



During the subsidence of the Champlain period, the Sound 

 again became an arm of the ocean, and one exceeding some- 

 what the present in its dimensions. But the existing beaches, 

 outside of the long sea- border bays, could not have been formed 

 before the present level was attained as ihe Champlain period 

 closed. 



2. The submerged River Channels. 



The map of the Atlantic border off New York and ~New 

 Jersey in my Manual of Geology, showing by bathy metric 

 lines the course of what had appeared to me to be the 

 submarine channel of the Hudson River over the shallow 

 border of the ocean, first appeared in the first edition of 

 the work, published in 1863, and I refer to it there (p. 411) 

 as proof " that the land was once above the water with 

 the Hudson River occupying the channel on its way to the 

 ocean." On page 544 of the same edition, it is added, that 

 " the Connecticut River Valley is also distinct over the 

 same submerged pleateau, running southward east of Long 

 Island." 



The soundings on which the bathymetric lines affording 

 these deductions were based were those of the Coast Survey 

 Chart of 1852. But the lines on the chart only imperfectly 

 defined the so-called Hudson River channel. A little closer 

 following of the registered soundings brought out the long 

 loops in the lines, and these were inserted in my little map. for 

 the Manual, and also in a copy of the chart of the Coast 

 Survey sent at the time to Professor Bache. 



Recently, in 1885, the facts bearing on the existence of the 

 submerged Hudson River channel have been presented in this 

 Journal by Mr. A. Lindenkohl, assistant in the U. S. Coast and 

 Geodetic Survey.* The author sustains the conclusion as to 

 the channel and presents others with regard to the " sea-bottom 

 in the approaches to New York Bay," illustrating his paper by 

 a map. 



. My own further consideration of the facts bearing on the 

 subject leads me now to question some points in the conclusion. 



1. The Connecticut River Channel. — As regards the ex- 

 istence of a submarine Connecticut channel the evidence referred 

 to is certainly unsatisfactory. The bend in the bathymetric lines 

 on the accompanying map between Montauk Point and Block 

 Island looks right for such an origin, and strongly so. But 

 considering the effects of tidal scour during the ebb through 

 the narrow passages of the Sound, briefly referred to above 

 (page 426), it is plain that the channel is of this kind. Block 



*Vol. xxix, 475, 1885. The article is entitled "Geology of the Sea-bottom in 

 the Approaches to New York Bay." 



