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THE POPULAR SCIENCE MONTHLY. 



the Ice age is shown in the interesting fact revealed by the United 

 States Coast Survey, and noticed by Prof. Dana, that the* old valley 

 of the Hudson River exists a well-defined depression in the bed of the 

 ocean through a distance of 89 miles southeastward from Sandy 

 Hook. It is termed on the Coast Survey chart " a remarkable 

 gorge." The soundings show that it comprises a continuous series 

 of deep depressions in the ocean's bottom. Some of these are eight 

 miles long and from one and a half to two and a half miles wide. The 

 map (Fig. 4), kindly furnished by the publishers of Prof. Dana's 

 " Manual of Geology," shows how the dotted lines of equal depths 

 bend toward Sandy Hook, indicating the line of deepest water, or 

 the old river-valley in question. 



Fis. 4. Map of the Submerged Border op the Continent off Long Island and New Jersey, with 

 Lines of Equal Soundings in Fathoms. (From Dana's " Manual of Geology," p. 422.) 



The Coast Survey chart shows us that at 28 miles from Sandy 

 Hook the depression is 90 feet below the banks or ocean-bottom on 

 either side. At 39 miles and at 51 miles the depression is 60 feet, 

 and at 74 miles it is 72 feet, and at 89 miles it is 492 feet. 



The average depth of the ocean over this depression is about one- 

 third greater than on either side. 



