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is siliceous santff'either transparent and white, or stained yellowish 

 by oxide of iron. The predominant reddish colour of the rock is 

 due to the minute particles and fragments of the red shale which 

 it contains. The beds here described yield altogether the best 

 building material upon the Delaware. The rock is pretty exten- 

 sively quarried at the State Prison Quarry, Green's Quarry, and 

 Hill's Quarry, and upon the opposite side of the river at Yardley- 

 ville. Its stratification is usually very regular, and it is easily 

 wrought ; and some of it seems capable, from its composition, of 

 resisting decay from atmospheric sources. This and the next in- 

 ferior group are discernible over a considerable range, pursuing a 

 direction nearly parallel to the canal towards Princeton, beyond 

 which they disappear beneath the overlapping strata of the upper 

 secondary or greensand series, a little to the east of Stony Brook, 

 and south of Kingston. 



Between the stream at Scudder's, five miles above Trenton, 

 and the small stream above the Alexsockin creek, near Centre- 

 bridge, the next extensive belt is embraced, occupying a breadth of 

 many miles. The rocks of this portion of the formation are well 

 exhibited near the Delaware, having been artificially excavated 

 in numerous places to make room for the bed of the Feeder of 

 the Raritan canal. They consist principally of those varieties 

 which form the usual and predominant materials of the whole 

 formation both in New Jersey and the adjoining States. The 

 ordinary species is a rather fine-grained brown or red argilla- 

 ceous sandstone, varying between soft argillaceous shale and 

 hard arenaceous and micaceous sandstone. 



The colour, though most usually red, is sometimes dull bluish, 

 or greenish. Much of the rock exhibits cross joints, in great 

 number and regularity, and gives proof of its having been some- 

 what consolidated by an elevated temperature, if we may judge 

 from its compactness, its baked aspect, and the ringing sound 

 which it returns when struck, and from the extent to which it is 

 divided by these cross joints. With one single exception, in its 

 whole breadth along the Delaware the dip is invariably to the 

 northwest, at about the usual inclination of nearly 20°. The 

 exception referred to, occurs between Alexsockin creek and the 

 ridge of trap about a mile above it, where the dike has burst up 

 through the stratified rock and thrown it out of its usual inclina- 



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