SPRINGS FROM THE CHAMPI.AIN DIVISION. 131 



n passes. Those which merely pass through sandstone retain the purity almost of rain 

 water ; while those which pass through limestones are invariably impure, or hard waters, 

 as they are termed. The water of the springs which issue from the Potsdam sandstone, is 

 soft, or very rarely so highly charged that it will not wash well. The waters issuing from 

 the slates of the Hudson river are more or less charged with saline matters ; and what is 

 worthy of remark, is, that they furnish many chalybeate and sulphur springs, or springs 

 whose waters contain hydro-sulphurous acid in solution. They are mostly weak, and of 

 but little medicinal value. 



The most interesting and important springs, however, issue from the Calciferous sand- 

 stone. It is this rock, for instance, which gives origin to the celebrated Congress spring of 

 Saratoga. This fact was proved two years since, when the spring was retubed. On care- 

 fully removing the deposit at the bottom of the spring, the water was found to issue from 

 a small hole or fissure in this rock. It is of course impossible to trace the water farther ; 

 but this shows that it is not from the clay which fills the valley, nor from the Hudson- 

 river rocks or slate of the Trenton limestone. 



It is not my purpose to attempt to give a detailed account of the springs of this celebrated 

 locality ; inasmuch as in the report of Dr. Beck, all the most important facts are embodied, 

 and may be consulted by the reader. Some independent observations, however, were 

 made by myself in the summer of 1844, which may be found of some interest. 



These springs issue from near a fracture in the lower rocks of the Champlain division. 

 The geological structure of the valley may be understood by the annexed diagram : 



Fig. 16. 



a. Calciferous sandstone. F. Fracture. 



b. Birdseye limestone. 1,2,3. Sand, yellow and blue clays, forming 

 ■c. Trenton limestone. the eastern side of the valley. 



Those who have informed themselves of the relative position of these rocks, will per- 

 ceive that there is both a fracture and uplift. The calciferous sandstone, which occupies 

 a position inferior to the birdseye and trenton, is at this place elevated above them. The 

 fracuire runs to the southeast, but the valley opens to the northeast. This fracture forms 

 quite a depression, which runs nearly parallel with Broadway, the principal street of the 

 village. We gain access to it at the south end of the street, near the site of Congress 

 spring, where the rocks are less elevated. It is not proved, as I have already remarked, 

 that any of the springs, except Congress spring, rise out of the calciferous ; but from the 

 fact of the existence of a fracture, we may infer with great propriety that they originate 



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