Geology of Hudson County, New Jersey. 63 



East River, N. Y. Tower of Brooklyn Bridge, 107.4 ft. to bed-rock. 



" Brooklyn Tower, " " 88 " " 



pier 41, N. Y., 200 feet from the 



building line of South St. , - 91 " " 



pier 18, " " 60 " 



Harlem River at High Bridge, center of river, 70 " " 



" Madison Av. Bridge, " " 75 " " 



As shown on the Coast Survey charts of J^vTeAV York harbor, the 

 water in the Hudson off Castle Point is - 50 — 65 ft. deep. 



In the East Eiver, W. of Blackwell's Island, 107 " " 



at Hell Gate, - - 131 " ^' 



Ward's Island, - 170 



" New York Harbor, - - - 60— 80 '' " 



" the Narrows, ... . 60—116 " " 



" the Kill Von Kull, - - - 25— 54 '' 



" Arthur's Kill, - - - - 20— 35 "' 



These soundings give the present depth of the water ; how 

 much the old channels have been filled with drift and silt is un- 

 known. All this shows, as has been graphically described by 

 Prof. J. S. Newberry,* that these channels are old river-beds, 

 eroded when the continent stood at least 500 feet above its pre- 

 sent level. 



The true margin of the continent lies at a distance of 80 miles 

 outside of the present mouth of the Hudson ; over this region, 

 once a broad littoral plain, the Hudson flowed after passing 

 New York and Staten Island. The position of this submerged 

 river-bed is shown on the Coast Survey charts by the line of deejj 

 soundings extending seaward from New York harbor. During 

 this time of continental elevation, previous to the glacial period, 

 the deep canon-like valley of the Hudson was excavated, and 

 also a great ]3art of the broad, deep valleys of the Haekensack 

 and Passaic ; these streams perhaps, after uniting, flowed through 

 Arthur's Kill and received the Earitan as a tributary. 



As we have already seen, there is no evidence that Hudson 

 County has been submerged since the close of the Triassic age ; 

 dui'ing all the vast time recorded in other regions by the deposits 



* The (leol. Hist, of New York Island. Popular Science Monthly, 1878. 



