131 



Passaic, a sandstone of a somewhat different composition and 

 appearance occurs on both sides of the river, though in the 

 immediate vicinity of the trap dike of the second mountain; it 

 preserves its almost invariable dip to the northw^est, which is 

 here at an angle of from 10° to 15°. This sandstone is of a very- 

 superior quality, both for the purposes of architecture and sculp- 

 ture, and the quarries which have been opened furnish blocks of 

 almost any dimensions. One of these quarries has been con- 

 ducted under the direction of Mr. Thom, the celebrated sculptor, 

 who has found in it a material extremely well adapted to receive 

 the admirable delineations of his chisel. 



From Paterson eastward to the Hudson, and northwestward 

 to the New York line, the formation exhibits little or no departure 

 from its ordinary type, as respects its composition, structure, and 

 the direction and degree of dip of its planes of stratification. 



The upper or northwestern half of the red shale and sandstone 

 formation, extending on the Delaware, between the mouth of the 

 Lockatong and the overlying conglomerate at Spring Mills, and 

 between the first trap ridge and the foot of the primary hills in 

 the country north of the Raritan, is nearly identical in composition 

 with the belt already described ; the chief departure from uni- 

 formity of structure in either district arising from the changes 

 induced by the numerous ridges and dikes of trap to be presently 

 considered. Adhering in this place to the plan proposed of pre- 

 senting a brief account of the formation in the different portions 

 of its range, by selecting a few characteristic localities where the 

 rocks are plainly disclosed in their prevailing features unaffected 

 by igneous agency, let us glance at the northwestern bell of the 

 formation beginning as before at the end next the Delaware. 



To the west of the wide area of altered shales, composing the 

 tract called the Swamp, we find a zone of ordinary red shale and 

 argillaceous sandstone, in the prolongation of the Nockamixon 

 rocks on the Delaware. Between Evittstown and Mount Pleasant 

 these strata are well seen under their usual type, dipping regularly 

 and gently to the northwest. To the southeast and east of 

 Evittstown an arenaceous variety of the sandstone aff^ords an 

 excellent material for architectural uses. Approaching Bap- 

 tistown, the rocks begin to manifest, by a change of colour and 

 texture, their proximity to the trap dikes of the Swamp. 



