No. 50.J 
445 
Lastly, when dry by evaporation or drainage, the vegetable matter has 
become compact, and firm enough to form peat, and is used for fuel 
The deposit of marl takes place prior to the grow^th of vegetation ; and 
results from the percolation of water through the alluvial soils, which 
contain large proportions of lime. When swamps occur in places 
where there is no alluvium or limestone, there is no marl. 
The number of swamps containing muck, is exceedingly numerous. 
This deposit in the fourth geological district, has but in few instances 
become sufficiently tenacious to be called peat ; though it burns as 
readily, and is equally good for fuel. In drying, it falls to powder^ 
not containing enough undecomposed particles to cause the mass to co- 
here. Sometimes the muck is deposited on a sandy bottom, when it is 
never so abundant as on clay. This understratum of clay is often very 
valuable for bricks. In many places, when the swamps shall have 
been drained, and time allowed for the muck to become more compact, 
and other vegetation to succeed the present, many of these deposits 
will become valuable fuel. 
Tufa and Marl. — These terms are applied to the same substance in 
different states of aggregation ; both being a deposit of lime, from solu- 
tion in water. The former is hard and porous, embracing vegetable im- 
pressions, and leaves and branches, which have been replaced by lime. 
This form results when the deposit is made from water passing over a 
surface or oozing from a hill side ; in the latter, the lime is precipitated 
under water in shallow lakes, ponds, &c. and from its manner of depo- 
sition, cannot cohere. 
A bed of tufa, which appears to be not very extensive, is seen in a 
hill N. E. from Dansville, on the land of Mr. Brewer. This has been 
burned for lime. Large quantities are obtained for that use at another 
locality in the same town, which I did not visit. On the Canisteo, a 
mile and a half from Bennetsville, a spring rising at a level of 60 or 70 
feet above the river, deposits calcareous matter. Near the source of 
the spring, the lime has accumulated, and the stones for some distance 
in its course are covered with the incrustation. Several similar springs 
are found in the neighborhood. 
Two miles northeast of Arkpoit, tufa is burned for lime, which thence 
supplies that part of the county. It was formerly burned at a place 
south of the village. At Pogues Hole, on the Canesaraga, at Troups- 
