176 GEOLOGY OF THE SECOND DISTRICT. 



or even any part of a mountain. It lies at the base, and forms low and inconspicuous hills 

 in the valleys. This belt, imperfect as it probably is, passes through Athol, Johnsburgh, 

 Warrensburgh and Chester, the district about Brant lake, and so on towards Lake Cham- 

 plain. It is extremely varied in its characters : at one time it is a pure coarse granular lime- 

 stojie ; at another, mixed with pyroxene, hornblende, quartz and scapolite ; all which occur 

 in the rock, in a mode precisely similar to that of granite, that is, invested on all sides by the 

 rock, showing conclusively that the minerals are cotemporaneous with the rock itself. 



This limestone is one of the most important rocks in the county, as from it all the lime 

 for building and for agriculture may be obtained. It requires, however, careful selection 

 when intended for these uses, rejecting those masses in which foreign minerals are dissemi- 

 nated. When the stone is properly selected, it makes the strongest of lime, a bushel of 

 which is worth a bushel and a half of the ordinary quicklime made from the transition lime- 

 stones. A very common error prevails in relation to this rock, most of the farmers mistaking 

 it for plaster. 



This limestone, as it occurs at the surface, is never suitable for building, being in a state of 

 partial disintegration ; but if obtained deep in the beds which have not been acted upon by 

 atmospheric agents, it is firm, and appears durable. Still the grain is loo coarse, and being 

 a magnesian rock, it will sooner or later crumble and fall into decay. 



This rock is rarely suitable to be employed as a marble, in consequence of its liability to 

 disintegrate ; besides this, it always contains hard minerals, as quartz, hornblende, augite, 

 sulphuret of iron, etc., which interfere with its working. This limestone, therefore, ought 

 not in general to be employed, except for making lime, especially when durability is an object. 

 For this purpose, Warren county is well supplied, in addition to the limestones at Glen's- Falls, 

 ■which are largely employed for quicklime. 



It is important to notice the fact, that limestone, at many of the localities, becomes a com- • 

 pound rock, by taking into its composition mica, presenting much the appearance of a white 

 granite ; thus at Chester and Warrensburgh, the micaceous varieties are abundant, and they 

 appear much like an ordinary grey granite, or a rock composed of white or grey feldspar 

 and mica. 



In addition to the uses already stated, for which this species of limestone has been employed, 

 it has been spread like plaster upon the soil : in some instances it has evidently produced a 

 favorable change ; in others it has been doubtful, or the effects have been so slight that it was 

 not easy to say whether any effect was produced or not. 



Serpentine Marble. 



Associated with primitive limestone, are extensive beds of serpentine intermixed with car- 

 bonate of lime, forming a mixture to which the above descriptive name has been applied. It 

 is usually called verd-antique ; but this ancient and beautiful rock is composed of materials 

 much harder, ai\d is more valuable. 



The most important bed of serpentine marble is upon the school lot in Warrensburgh, a 



