Geology of Hiodmn County, JYew Jersey. 27 



IV'. — On the Geology of Hudson County, Neiv Jersey. 



BY ISRAEL C. RUSSELL. 

 Read April 19th, 1S80. 



The eastern boundary of Hudson County is the middle of the 

 Hudson Eiver ; at Bull's Ferry the line leaves the river and 

 bears northwest until Bellman's Creek is reached, which it fol- 

 lows to the Hackensack Kiver ; thence the latter stream is 

 the boundary, to the mouth of Sawmill Creek, which comes 

 in from the westward ; the boundary then follows Sawmill Creek 

 to the point where that stream is crossed by the Belleville 

 turnpike, which then becomes the boundary as far as the middle 

 of tiie Passaic Eiver ; the line tben follows the centre of that 

 I'iver to Newark Bay, and then through the centre of the bay to 

 the Kill Von Kull, through which it passes and joins the east- 

 ern boundary.* The area thus inclosed comprises about 51 

 square miles, of which 6.4 sq. m. are covered by water. 



The most prominent feature in the geology as well as in the 

 geography of Hudson County, is the great ridge of trap-rock 

 which traverses it from north to south, and forms the elevated 

 portion known in different parts of its course as Bergen Hill, 

 Jersey City Hights, Hights of Weehawken, etc. This same 

 ridge of trap continues northward, forming the bold, picturesque 

 Palisades along the west bank of the Hudson ; at Haverstraw, 

 where an elevation of over a thousand feet is attained, the trap- 

 ridge sweeps around sharply to the westward, forming the Hook 

 Mountains, so well known to all who are familiar with the beauti- 

 ful scenery of the Hudson. 



In order to understand the topography of the region we are 

 studying, it is necessary to remember that this ridge, forming 

 the back-bone of the county, is the outcropping edge of an im- 

 mense irregular sheet of very hard crystalline rock, which dips 



* For more detailed information, consult Public Laws of N. J., 1840, p. 65. 



