of the Eastern States. 241 



division of the Triassic series in the State of New Jersey : 

 The Eruptive Rocks. 



In New Jersey the Triassic area is traversed by three main 

 ridges of trap rocks, besides several much smaller detached hills 

 and ridges of the same structure. Of these ridges, the first to 

 claim our attention, and the largest of the series in the State, 

 commences in the extreme northern extension of the Trias in 

 Rockland Co., New York, and extends southward along the 

 western shore of the Hudson as far as Jersey City. This is the 

 outcropping edge of an immense sheet of crystalline rock which 

 conforms in bedding to the associated sandstones and shales, 

 and presenting an almost perpendicular face to the eastward, 

 forms the picturesque Palisades which give to our noble river 

 some of its most beautiful scenery. The height of this ridge is 

 about one thousand feet at Haverstraw, and gradually dimin- 

 ishes southward, until at Bergen Point it is scarcely above low 

 water. On Staten Island it appears again, but as we follow it 

 southward it soon becomes covered with Cretaceous clays, and 

 is no longer observable at the surface. 



What seems to be the southern extension of this same tra}> 

 sheet, appears again south of New Brunswick, and extends to 

 the Delaware River, and over into Pennsylvania. This im- 

 mense sheet of eruptive rock, which traverses the entire length 

 of the Triassic area in New Jersey, forms a great curve over 

 seventy-five miles in length, with its convex side to the east- 

 ward and its ends bent sharply toward the west. It is remarka- 

 ble that this peculiar curved outline can be traced, as we shall 

 see, in almost all the trap ridges of the Trias. About nine 

 miles westward of the central portion of the Palisade range, 

 we find a second curved ridge of trap nearly parallel in outline 

 with the first. This is known as the First Newark Mountain, 

 which is about 40 miles in length, with an average height of 

 three or four hundred feet. Like the Palisade range, it slopes 

 gently westward, and presents a steep mural escarpment to- 

 wards the east. Again, westward of this and concentric with 

 it, we find the somewhat larger and broader range of the 

 Second Newark Mountain. These two are separated by the 



