Geology of Hudson County, Netv Jersey. 33 



debris from the red sandstone rocks through which it passes ; 

 its walls ai'e altered in texture and color as if by the action of 

 heat, and when freshly broken are of a bright brick-red color. 

 The fragments filling the fissure are small near the walls, and 

 imbedded in an earthy or shaly mass ; they are usually rounded 

 and show polished or ''slickenside" surfaces. The central part 

 of the fissure is filled with larger masses of sandstone, which 

 sl]ow more alteration, both in texture and color, than the walls, 

 and have also slickenside surfaces. The bedding of the sand- 

 stones and shales is unaltered where they approach the fissure. 

 The metamorphic action is not confined to the immediate walls 

 of the fracture, but may be traced at least seventy-five or a hun- 

 dred feet on either side. These facts seem strongly to indicate 

 that the fissure not far below the surface is filled with igneous 

 rock, the heat from which has partially metamorphosed the 

 rocks now exposed. This fissure has still greater interest when 

 studied in connection with the dikes and sheets of trap occur- 

 ring along the west bank of the Hudson. 



It is not out of place to state here, that no fossils were dis- 

 covered during the construction of the railroad cut at Arlington, 

 and that no foot-prints, rain-drop impressions, sun-cracks, etc., 

 were found ; the only markings that occur here are very obscure 

 impressions, that have the general appearance of sea- weeds or 

 worm-burrows. The sandstones and shales here so well exposed 

 give a fair representation of the character of the Triassic rocks 

 covering a large portion of New Jersey, except that in some in- 

 stances the sandstone is lighter colored and more feldspathic. 



Not more than a mile northward of Arlington, and on a line 

 with the fracture we have described as occurring in the railroad 

 cut, the copper-mine near Belleville is situated. This is known 

 as the Schuyler Mine : it has been worked at intervals since 

 1717, and has been extensively wrought, as the abandoned shafts 

 and galleries testify. The rock here is a light-colored or nearly 

 white sandstone impregnated with the carbonate of copper ; the 

 silicate and red oxide of copper are also present. The sand- 

 stone is traversed in places by thin sheets of trap, although no 

 dikes or sheets of this rock appear at the surface: it is thus seen 

 that the copper-bearing sandstone here has the same geological 

 relations as that occurring in other places in the Triassic area of 



