32 Geology of Hudson County, Xeiu Jersey. 



Associated with the serpentine at Hoboken, and overlying it. 

 there occurs an exceedingly hard jasperoid rock,* which was for- 

 merly to be seen in the neighborhood of the Stevens Institute, 

 but has since been concealed by buildings and park improve- 

 ments. We have referred this rock to the Archaean series, as 

 will be seen in the generalized section of the rocks of Hudson 

 County, accompanying this essay, but can offer little informa- 

 tion concerning it. 



Tkiassic Rocks. 



Sandstones, Shales and Slates. — Resting on the upturned and 

 probably eroded edges of the gneiss and mica-schist in Hudson 

 County, are sedimentary beds of Triassic age, which, like the 

 Archaean rocks alread}^ noticed, are in most cases but indif- 

 ferently exposed. The Triassic formation appears usually as 

 evenly bedded strata of reddish-brown standstone and soft red- 

 dish sliale, togetlier with thinly stratified slates — the whole series 

 dipping towards the northAvest with great uniformity at an angle 

 of about fifteen degrees. 



On the extreme western border of Hudson County, forming 

 the high narrow ridge that sejiarates the Newark Meadows from 

 the valley of the Passaic River, the reddish-brown sandstones 

 and shales are splendidly exposed. This ridge has nearly as 

 great an elevation as Bergen Hill, and indicates in a very strik- 

 ing manner the vast amount of material that has been removed 

 by erosion from the country now occupied by the Newark 

 meadows. In the deep cut made for the passage of the New 

 York and Greenwood Lake railroad, extending from Arlington 

 to the Passaic River, the strata of reddish-brown sandstones are 

 thinly bedded, the strata seldom being over two feet thick, with 

 partings of red shale between, the whole series inclined at the 

 normal angle of fifteen degrees towards the northwest. One of 

 the most interesting features in this section is the occurrence 

 near the middle of it of a fissure which has parted the rocks 

 in a nearly north and south direction, or parallel to their 

 strike. This fissure is about five feet wide, and is filled in with 



* We adopt the name proposed for this rock some ten years since by Dr. Henry Wurtz. 



