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AGRICULTURAL- GEOLOGY. 187 



tion of a variety of geological causes. On the east side of this 

 system, the quartz rock reposes against and upon the gneiss and 

 ;nica slate of the Green mountains ; and on the west, the Taconic 

 5late passes beneath the New-York system in the Hudson and 

 Champlain valleys, which fact may be seen at Burlington, Charlotte 

 aid Addison in Vermont, and at Whitehall, Bald mountain, Galcs- 

 nlle, Granville, Lansingburgh, Troy and Greenbush in New-York, 

 )csides many other places which might be mentioned. The order 

 n which they may be studied to the greatest advantage, is to pass 

 ner the system from west to east, or from the great vallies of the 

 ludson and Champlain to the top of the Green mountains. The 

 );inds or belts of rock which have been described, will be found in 

 he range of the places which have been given, either north or south 

 if them as the student may be located. 



Springs of water. 

 The springs which gush from the Taconic hills, and which have 

 heir origin mostly from the slate, in many instances yield com- 

 laratively pure water ; at least, it contains less lime in combination 

 irith acids, than is found in the water from the slates of the Hudson 

 iver. We have springs which contain only four grains of solid 

 aatter to the gallon. A few weak chalybeate springs flow from the 

 lates without regularity : they are all small, and take their origin 

 rem the slate, charged with sulphuret of iron or pyrites. The most 

 iteresting springs, however, are the nitrogen springs of Hoosic, 

 ebanon and Williamstown. The water of these springs is soft, and 

 as a temperature above the mean of the place in which they are 

 ituated. They do not come out from any one of the rocks exclu- 

 ively, but are supposed to indicate a fracture extending deep in the 

 owels of the earth, and with which they are connected. These 

 )rings, too, are the largest which occur in this vicinity, some of 

 fiij lem discharging sufficient water to turn a mill-wheel. The wells 

 ;jii f the valleys, especially when sunk in clay, fill with hard water, 

 id frequently contain gypsum in solution ; but when sunk in gravel 

 r sand, they often furnish soft water. The temperature of the 

 rater of some of these wells is as low as the mean of the place, 

 it differing much from 45°. 



The form and surface of the whole section under consideration 

 well calculated to furnish a great abundance of water, in springs, 



VOL. II. — NO. II. B 



