30 Geology of Hudson County, New Jersey. 



semblcd some of the trap rock at Bergen Hill at first glance. 

 There was a second reef of the same nature formerly to be seen 

 at the southern end of Washington Street, where it crosses the 

 Morris Canal ; this reef was penetrated to the depth of a thou- 

 sand feet by a well bored at Matthieson and Wiecher's sugar re- 

 finery ; the rock was reported to be mostly gneiss containing 

 mica and quartz, and near the bottom "white sandstone and 

 shale. '"(?) Both these exposures of gneiss and mica-schist, un- 

 derlying Jersey City, have now been covered with earth, and 

 the pier-heads carried beyond them. There is but little doubt 

 that this same line of reefs extends southward of Jersey City, 

 and forms the main portion of Ellis's, Bedlow's and 03'ster 

 Islands, and Robbins's Eeef. This belt of Archa?an rocks reap- 

 pears on Staten Island, but is soon covered by more recent 

 deposits ; it again comes to the surface at Trenton, and is again 

 concealed nearly to Philadelphia, whence it stretches far to the 

 southward. Although this formation has but slight economic 

 importance in Jersey City, further than forming a firm 

 foundation on which to buildj and has but little immediate 

 influence on the health of the people, yet its physical history 

 makes it an interesting subject of study for the geologist. 



Seiyeniine. — The serpentine associated with the belt of Ar- 

 chaBan rocks that borders Hudson County on the east, is the 

 dark-green variety, as distinguished from the light greenish- 

 yellow or precious serpentine found in other localities. The 

 cliffs overlooking the Hudson at Castle Point, Hoboken, present 

 a fine exposure of this dark-green eai'thy rock ; it shows con- 

 siderable variation, however, being sometimes yellowish and dull 

 in appearance, and so earthy and incoherent as to crumble be- 

 tween the fingers. In some places it is quite compact, and may 

 be dressed so as to furnish an ornamental although inferior 

 building-stone ; it has been used with very pleasing results in 

 constructing the beautiful gateway and j)orters lodge at Castle 

 Point. 



The hill of serpentine at Hoboken is less than half a mile in 

 length along the river bank, and from two to three hundred feet 

 wide, and covers an area of about thirty acres. Seemingly it is 

 the northern exposure of a belt of this kind of serpentine that 

 has been reached by boring at a depth of 179 feet at the end of 



