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but which contains, besides the ordinary ingredients, various 

 other minerals, as epidote, serpentine, indurated talc, compact 

 steatite, and jade. In some places the white limestone is wanting, 

 having been evidently removed by denudation, as indicated by 

 the rolled fragments occasionally met with in the adjoining 

 plain. But even where it is absent, we observe the usual narrow 

 ridge with its peculiar dike of heterogeneous mineral matter. 



Towards the northeastern end of the belt, about two miles 

 southwest of the road which leads to Long Bridge, the road 

 parallel with the base of the mountain runs in a little narrow 

 strip of meadow between the dike, which here shows a nearly 

 vertical wall, and a second parallel small ridge, rising imme- 

 diately on the southeast, and which is composed of the sparry 

 limestone and altered chert, dipping at the steep inclination of 

 80° towards the southeast. The ridge on the northwest of the 

 road, containing the dike, would seem to include, besides a bed 

 of the altered limestone, having a distinct dip at this spot to the 

 north-northeast of 70°, several magnesian rocks, as serpentine, 

 greenish jade, Saussurite, and indurated talc. 



The primary rocks in this vicinity, in the base of Jenny Jump, 

 display marks of the most violent disruption and compression of 

 their strata, exhibiting an unusual number of intrusive dikes and 

 veins, in which, as in those immediately affecting the limestone, 

 we notice a remarkable diversity of mineral composition. The 

 constitution of the dike, or chain of dikes, directly in contact 

 with the altered limestone, though variable, is essentially different 

 from that of the igneous veins disturbing in a parallel line the 

 primary strata at the base and on the side of the mountain, being 

 characterized by a predominance of the minerals of the magne- 

 sian class. 



We have evidence that the limestone at one time spread itself 

 extensively along the base and slopes of Jenny Jump ; for, not 

 only do we find, on the sides and even summit of the mountain, 

 scattered blocks of the stratum and its included chert in consi- 

 derable number and size, but we observe traces of its having 

 undergone fusion and incorporation with the materials of some of 

 the dikes and veins before alluded to, at the southeastern foot of 

 the mountain. Though the white sparry rock is no longer visible 



