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coloured sandstone pebbles. Sometimes there is a considerable 

 mixture of pebbles from the primary rocks ; and in certain parts 

 of its range, the stratum consists, throughout nearly the whole 

 thickness, of pebbles of limestone, firmly cemented by a limestone 

 paste. Usually, the cement or imbedding paste contains a sensible 

 proportion of the materials of the red argillaceous shale of the 

 stratum beneath. In fact, where the Baltimore and Ohio railroad 

 crosses this rock in Maryland, the chief part of the cement is 

 nothing else. This admixture of red matter in the rock in New 

 Jersey is easily explained. The harder sandstones and the lime- 

 stone have retained the fragmentary state, while the soft red shale 

 has been reduced to powder or mud, by the violent action which 

 bi ought together this vast mass of water- worn materials. 



A large portion of the formation in its course across New 

 Jersey, exhibits all the characters of the rock which forms 

 the columns of the Hall of Representatives at Washington, and 

 which has received the name of the Potomac Marble. The most 

 northeastern locality of this rock which occurs within the State, 

 is on the Ramapo river, near the village of Pompton. It is 

 traceable in all its obvious features, in a belt of more than 

 a mile in length, passing in the immediate neighbourhood of 

 Ryerson's. Here its actual contact with the inferior sandstone 

 formation was detected, and the conformability of the rocks 

 clearly ascertained. Over the red sandstone rests a bed of rather 

 thin siliceous slate, the upper portion of which is somewhat 

 calcareous ; and immediately upon this reposes the very close 

 conglomerate containing a pretty large share of limestone pebbles. 

 This occurs near the Ramapo, a mile to the northeast of 

 Ryerson's. The dip of the whole is to the west, the angle being 

 between fifteen and twenty degrees. 



The conglomerate is seen again with the same dip about half a 

 mile to the west of this, and contiguous to a ridge of gneiss, which 

 appears to have caused some local displacement of the neigh- 

 bouring strata. This is upon the border of the plain through 

 which the Ringwood stream passes. It seems altogether probable 

 that the difficulty of tracing the conglomerate more extensively 

 in this quarter arises, first, from the irregularities in the direction 

 of the strata, caused by the intrusion of the trap ; and in the next 

 place, from the western part of the formation resting beneath 



