226 GEOLOGY OF THE THIRD DISTRICT. 



Where deposits of allavial materials exist which contain limestone pebbles, the water which 

 passes through them will deposit tufa at its egress, unless too rapidly carried off, and united 

 to larger bodies of water from sources of a different kind. Small deposits of tufa from sources 

 of the kind have frequently been found in the southern counties, and used for lime. Nume- 

 rous other deposits will yet be discovered, when under drainage will generally be practised ; 

 for accumulations of the kind must be found in many low and marshy situations in the sou- 

 thern counties, from the great abundance of northern alluvial containing pebbles, etc. of 

 limestone, which there exists. 



Calcareous Txjfa. 



This product without doubt conamenced with the first exudations into the valleys when 

 freed from water, and has continued to form unto this day. It is an exceedingly abundant 

 product, its localities being very numerous, jmd the quantity prodigiously great at some of 

 them. It differs from marl as before mentioned ; the latter having separated from its solvent, 

 in water, by which its parts were kept separate, and finally subsided or precipitated ; whilst 

 the tufa, on the contrary, separated where air had access, or its solvent could gradually escape, 

 by which its particles were enabled to cohere and form a soUd substance. 



One of its most abundant sources has been the calcareous portions of the gypseous deposit ; 

 the mass being permeable to water, this fluid deposits the tufa after passing through the mass, 

 and appearing again at the surface of the earth. The deposits generally appear at the sides 

 of the hills or valleys near the point where the calcEireous waters issue, and continue down in 

 many instances to a considerable distance, should their course be obhque, or above the drains 

 of the valley, else they are arrested by the waters of the valley. Sometimes where the 

 deposit has been rapid, a mixture of the earth or marl and the tufa takes place ; as on Lime- 

 stone creek, to the south of Delphi ; at the hill back of Brothertown in Oriskany valley, etc. 



The first deposit of note to the east, is north of Cherry- Valley, on the farm of Mr. Schism, 

 not far below the falls at Judd's mill ; large masses appear upon the surface over em acre or 

 more of ground, on the east side of the creek. 



A curious deposit, from its cavernous natxure, exists in the ravine below the new mill north 

 of Vanhomsville. 



A deposit appears on the creek about three miles south of Fort-Plain. 



A considerable mass exists on tlie farm of Judge Loomis, west of Little-Falls, by the road- 

 side. It is a deposit from a copious spring, issuing from the alluvial hill which skirts the north 

 side of the river. The Judge has conmienced using it upon his land, and is well satisfied 

 with the result, though but the first year of trial. 



Tufa appears in all the creeks along the south of the Mohawk through Herkimer county ; 

 the largest deposits noticed were near Fish's distillery, and Myers creek above the furnace, 

 the latter a very solid one, and is used at the furnace, and is burnt into lime. 



In Oneida county, it shields large portions of the hill-sides of Oriskany valley, immense 

 deposits existing on both sides, but more exposed on the cast side below Ely's sawmill, covering 



