408 JULIEN 



shore near high tide level, at Tompkinsville ; though its con- 

 tact with this later intrusion would not necessarily indicate its 

 lower limit. Passing northward, serpentinoid has been found 

 at Constable Point/ At Jersey City a layer was met, a few 

 feet in thickness, at the depth of 20 feet, on the south side of 

 the Morris Canal, at the foot of Washington Street ; at the Pa- 

 vonia ferry, at the bottom of a boring of 63 feet ; at the end of 

 Long Dock, by a boring at the depth of 1 79 feet ; and in wells 

 on Ninth Street, near Grove Street, at a depth of 700 and 

 800 feet. 



Near the south end of Grand Street, Hoboken, at the depth 

 of 40 feet in the marsh, a well was sunk 360 feet farther, ap- 

 parently in serpentinoid. At Castle Point, the main outcrop 

 less than half a mile in length along the river bank, descends 

 below the water-level and is supposed " to rest upon the gneiss 

 rocks which outcrop farther south." ^ About one fifth of a 

 mile further north, it is reported to have been found by drilling 

 at a depth of 175 feet. 



These notes show great variation in the form, thickness and 

 position of the serpentinoid sheet, perhaps in conformity with 

 sharp flexures usual in the enclosing beds of gneiss. Some 

 suggest the possible existence of another underlying sheet or 

 sill of the same rock. It has been shown by Dana^ and F. J. 

 H. Merrill that the axes of folds of the Manhattan beds gen- 

 erally pitch gently toward the southwest. As this bed of ser- 

 pentinoid is located in that direction from Manhattan Island, at 

 the distance of a mile, it may represent, unless brought up by 

 an intervening fault, an intercalation in the uppermost part of 

 the stratum. 



Microscopic CJim^actcristics of the Serpentinoid. — The serpen- 

 tinoid of Staten Island has been already subjected to careful 

 examination in specimens from several localities.^ Amphibole 

 was found in abundance, associated with serpentine, talc, 

 chlorite, chromite, magnetite, and occasional bronze-colored in- 



nV. W. Mather, Nat. Hist, of N. Y., Pt. I, Geol. of First Dist., 1843, 284. 

 2 1. C. Russell, Geol. of Hudson Co., N. J., 69-70; Mather, op. cit., 603. 

 ^ A in. Jour. 6'«., (3), XX, 1880, 361. 

 * Newland, loc. cit., 313, 316-317. 



