90 NEW YORK STATE MUSEUM 



trusives, while the New Jersey side is represented by different 

 varieties of arkose and gray and brown sandstone belonging to the 

 Newark series. 



It should be noted that although only one hole marks rock bottom 

 as low as 300' (that one situated 2180' from the New York bulk- 

 head about the middle of the river), yet there is at least a iicx) foot 

 space on each side which is essentially unexplored, and within one 

 of these spaces there may be a deeper gorge. 



The cores taken from the east side of this middle zone belong to 

 facies of the Manhattan schist formation, while those on the west 

 side ibelong to the Newark series. The middle one, however, is 

 essentially a soapstone or serpentine and may be a continuation of 

 the Hoboken serpentine belt. In any case, it belongs in age to the 

 older series of formations. 



It is certain that here again, 50 miles below Storm King locaUty, 

 a very deep gorge, if one exists, must be comparatively narrow. 



Submarine channel. It is worth noting in this same connec- 

 tion that a submerged gorge has been mapped by the Coast and 

 Geodetic Survey on the continental shelf from the vicinity of 

 Sandy Hook to the deep sea margin, a distance of more than a 

 hundred miles. This is interpreted by Spencer^ and others with 

 apparently sound argument as the lower portion of the old pre- 

 glacial Hudson gorge formed during an epoch of great continental 

 elevation. The outer portion of this submerged gorge is very deep. 

 That section near shore is shallow and obscure. It has been 

 assumed that this obscurity and shallowness is due to offshore and 

 river deposition, filling the channel with silt. No better explanation 

 is yet forthcoming. But even here the width of the submerged 

 gorge is suggestive. In very much softer sediments than any en- 

 countered in its whole course on present land, and in a part of its 

 course from 50 to 100 miles below the other sections, the river has 

 cut a gorge only 4000 feet wide at top and 2000 feet deep within 

 a broader valley 5 miles wide. In its deepest known part the 

 proportions are 10,000 feet in width at top to 3800 feet in depth. 



From this it would appear that the inner gorge type of develop- 

 ment is characteristic of the Hudson, and that it was originally an 

 exceedingly narrow one compared to the present river width, indi- 

 cating rapid erosion during a brief and comparatively recent epoch. 

 This submerged continental margin condition is favorable to the 



1 Spencer, J. W. The Submerged Great Canyon of the Hudson River. 

 Am. Jour. Sci. 1905, v. 19. 



