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region, more particularly, has been invaded, it becomes impossi- 

 ble to trace with any accuracy the limits of the several subdivi- 

 sions, even presuming them all to have been once continuous 

 strata ; I shall, therefore, merely attempt an account of a number 

 of localities, referring the beds described as nearly as practicable 

 to their respective belts, as seen along the Delaware, and in doing 

 this shall observe the usual ascending order, proceeding from the 

 southeastern members of the formation to the northwestern. 



Advancing from the Delaware towards the northeast, the first 

 or lowest beds, reposing on the gneiss rock near Trenton, re- 

 tain their coarse heterogeneous composition until they pass 

 beneath the marshes of the Shipetaukin creek, and the canal 

 south and east of Princeton, beyond which they are buried by the 

 overlapping white sands and clays of the upper secondary series. 

 On the declivity, or low escarpment, which bounds the valley of 

 Stony Brook, near Princeton, about a mile southeast of the town, 

 we find, near the canal, a gray arenaceous sandstone, which ap- 

 pears to constitute the upper part of this division, being overlaid 

 by the more argillaceous and reddish group of beds next north 

 of it. The rock at this place has been quarried, and supplies an 

 excellent building stone. The main edifice of the college, and 

 several recently erected edifices, in Princeton, are constructed 

 of it. 



The next belt, extending on the Delaware from Hill's creek to 

 Scudder's creek, crosses the canal near Kingston. Here, and 

 along the southern side of the Sand Hills, it encounters the trap 

 ridge, prolonged from Rocky Hill, its beds undergoing some inte- 

 resting modifications of structure, which will be more fully de- 

 scribed when we come to treat of the trap rocks specially, and 

 the changes induced by them. 



Viewed comprehensively, the next subdivision of the formation 

 should embrace the entire series of argillaceous red sandstones 

 and shales, included between these arenaceous rocks and the 

 calcareous conglomerates which overlie the whole, for it is ob- 

 vious that some of the varieties separately described as occurring 

 near the Delaware, owe their peculiar texture to igneous actions 

 of a merely local nature. Such is the case with the thick group 

 of beds composing the tract called the Swamp. Other subordi- 

 nate strata, like the coarse sandstones near Centrebridge, would 



