PETRIFYING SPRINGS. 157 



is well exemplified in the formation of those small stalactites which are often found attached 

 to the arches of aqueducts on our canals. The water contained in these aqueducts percolates 

 through the limestone of which they are constructed, and thus becomes charged with carbonate 

 of lime, which it again deposits when exposed to the air.* Many localities occur in this State, 

 where extensive calcareous incrustations are formed in a similar manner. There is a very 

 interesting exhibition of this kind near Camillus in Onondaga county, where, below the marly 

 clay and beds of gypsum, these calcareous incrustations are found, which are both fibrous and 

 crystallized ; sometimes existing in regular strata ; and at others, forming the walls of cavities 

 of various figures and dimensions. 



Simple as the explanation of these phenomena may seem, when it is known that water in 

 its natural state always contains air and carbonic acid, which enable it to hold in solution a 

 small quantity of carbonate of lime, it is not so easy to comprehend all the circumstances 

 which attend the process of petrifaction, or the conversion of vegetable into stony matters ; 

 for it is to this only that our attention will at present be directed. That the most delicate 

 parts of vegetables should be replaced by carbonate of lime, or silica, without any alteration 

 of their form, is certainly one of the most curious operations going on in the laboratory of 

 nature. 



As might be inferred from what has already been said, these petrifying springs are most 

 common in limestone regions. They therefore abound in the western parts of the State, al- 

 though they are by no means confined to them. 



Calcareous tufa is deposited from the water of springs near Whitehall in Washington 

 County, and it is also to be met with in the Counties of Franklin and St. Lawrence ; 

 as, for example, near the Chateaugay Corners, and also about four miles from the village of 

 Gouverneur. 



In Schoharie County, tufa is found in great abundance on the sides of the mountains, 

 from five to fifteen feet in depth, containing fine impressions of leaves, and covering grasses 

 and mosses with incrustations so delicate as to preserve distinctly every fibre. And here it is 

 to be remarked, that old deposits are covered with vegetable loam, on which shrubs and trees 

 are growing.t 



A very remarkable deposit of a similar kind is found near the head of the Otsquaga creek, 

 in Herkimer County. It proceeds from the slate rocks, which are either the upper layers 

 of greywacke or the calciferous slate. The calcareous tufa which proceeds from these rocks, 

 contains the impressions of numerous plants of the same species which are now growing in 

 the vicinity. There is a single mass on the bank of the creek, about three hundred feet long 

 and fifty feet wide, and from ten to forty feet thick. It is very irregular in its form, and near 

 the north end it is cavernous. Several rude apartments may be entered, which present curvi- 



» The stalactites pendant on the arches of the aqueducts of our canals, have been called nitrate of lime ; but all those which I 

 have examined are pure carbonate of lime. 



t See a valuable paper on the Geology and Mineralogy of Schoharie County, by John Gebhard, Esq. American Journal of 

 Science, XXVIII. 172. 



