68 



the width at the base being not less than a fourth of a mile, and the 

 length rather more than one mile. Besides the mass of altered 

 limestone, these ridges comprise portions of Formation I., toge- 

 ther with beds of the gneiss, both in a highly disordered and shat- 

 tered condition, with more than one extensive dike of igneous 

 matter, the immediate cause, most probably, of these disturbances. 



From the confusion which accompanies all these rocks, none 

 of them can be found, even for a short distance, possessing any 

 regularity of dip. 



The gneiss rocks of the Pochuck Mountain, on the contrary, 

 are distinctly seen dipping steeply towards the valley to the 

 southeast. 



The most conspicuous display of the crystalline limestone is at 

 the two extremities of the ridge which lie nearest Hamburg. 

 Between these points, towards its central portion, the same ridge 

 contains a large well-known deposit of brown or hematitic iron 

 ore, occupying its summit and sides, and penetrating deeply into 

 the body of the hill ; details regarding this valuable iron mine 

 will be given under another head. 



Separated from the Hamburg belt of altered limestone, by a 

 spur of the Wallkill Mountain, there exists another band of the 

 crystalline rock on the Sand Pond creek, about one mile and three 

 quarters southeast of Hamburg. Tliis commences near the south- 

 western termination of a small knob of gneiss. 



Though highly crystalline, the limestone still retains consider- 

 able regularity of stratification, dipping towards the west-north- 

 west, at an angle of 20°, being well exposed in a quarry, (the 

 property of Wm. Edsall,) where it is used for making pure lime. 

 It is white, and highly crystalline, and contains disseminated 

 scales of graphite. This line of altered rock ranges south-west- 

 ward nearly to the turnpike, and is met with again on the road 

 to Sparta, about half a mile beyond the turnpike. 



Between the small knob of gneiss, above spoken of, and the 

 Wallkill Mountain, to the southeast, we meet with another depo- 

 sit of brown or hematitic iron ore, a little beyond the termination 

 of the crystalline limestone, none of which, however, is discovered 

 near it. This ore will be more minutely described in another 

 place. 



