129 



An explanation of the probable cause of the unusual dip 

 assumed by the strata in this quarter will be attempted under 

 another head, while discussing some of the physical circum- 

 stances which attended the formation of this whole series of 

 middle secondary deposits. 



Extending our observations northeast of the Raritan, we meet 

 with few features in the geology of this belt of the red sandstone 

 tract deserving of a special description, until we reach the neigh- 

 bourhood of Newark. The direction of the dip, wherever this 

 can be noticed, is towards the northwest at an angle rarely 

 exceeding 15°. Between Boundbrook and Scotch Plains, along 

 the valley of Greenbrook, so general is the covering of diluvial 

 matter for three or four miles east of the base of the first trap 

 ridge, that it is impossible to ascertain whether the synclinal axis 

 passing from Flaggtown to Boundbrook is prolonged in this 

 direction. The existence of a regular northwestern dip in the 

 strata between the first and second trap ridges, at points north of 

 Plainfield and Scotch Plains, renders its continuation far to the 

 northeast of the Raritan very improbable. 



The surface of the formation is covered throughout nearly the 

 entire distance between Rahway and Plainfield, by a deep sandy 

 loam, imbedding occasionally loose fragments of sandstone and 

 some rolled masses of primary rocks derived from the Highlands. 

 A level, sandy plain, stretching for some miles in length, from 

 northeast of Scotch Plains to southwest of Plainfield, exhibits a 

 succession of fine farms, and several thriving villages. An abun- 

 dance of excellent water is usually procured by descending about 

 fifteen or sixteen feet into the diluvial sand and gravel. 



The country included between Rahway, Elizabethtown, and 

 Newark, on the east, and Scotch Plains and Springfield, on the 

 west, is very similar in its general aspect, being rather level, with 

 occasional gentle swells and undulations of the surface. The soil 

 is a fertile reddish sandy loam, well cultivated. Boulders and 

 loose fragments of rock are fewer on the surface here than a few 

 miles further towards the northeast. Throughout much of this 

 area the underlying rock is deeply covered. 



Pursuing our course to the northeast, the sandstone is exposed 

 in a quarry above the village of Jefferson, in the immediate vici- 

 nity of the trap rock, dipping to the usual quarter, the northwest, 



