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accordingly, that we find it upon the Delaware, where its beds, 

 observing a gentle northwest dip, abut unconformably against 

 the liighly upturned strata of the older limestone, reposing with a 

 steep southeastern dip upon the primary rocks in the flank of the 

 Musconctcong Mountain. 



The more calcareous variety of this rock, where the cementing 

 matter is not too soft, affords a material of the highest beauty for 

 ornamental uses ; and it is a subject of surprise that so little has 

 been done to call attention to its numerous applications. The 

 rock is frequently so exclusively composed of materials derived 

 from limestone, that it makes as good a lime by burning as many 

 strata which do not possess the conglomerate structure. It has 

 been in reference to this, its most valuable property, that I have 

 felt especially solicitous to fix as nearly as possible the range 

 which it pursues across the State, that farmers in the northern 

 portions of the red sandstone district, needing lime for the im- 

 provement of their agriculture, might be induced to seek it from 

 this formation, which, when it is sufficiently calcareous, is of 

 course the nearest source. 



The theoretical views respecting the mode of origin of these 

 masses of calcareous and siliceous conglomerate which overlie 

 the red sandstone formation, suggested by their various geological 

 relations, will be presented in a subsequent section, after treating 

 of the trap rocks and the changes induced by them. 



To that part of the Geology of the middle secondary region, I 

 now proceed. 



Of the Trap Rocks, and Phenomena evincing Igneous Action. 



Geographical range. — Between the Hudson and Delaware 

 rivers, the middle secondary or red shale region is traversed in a 

 longitudinal direction, from north-northeast to south-southwest, 

 by a number of nearly parallel ridge^ and dikes of trap rock, 

 some of which are of great length and uniformity of structure. 

 Some of these are nearly straight over a course of many miles, 

 others are considerably curved, and several again are of a nearly 

 semicircular form. The height of the larger of these belts is 

 about four hundred feet, while many have not more than half or 

 even one-fourth of this elevation. In one class of these ridges, 



