192 
[Assembly 
to be wholly useless when burnt, for nnortar, or whitewash, but 
may answer agricultural purposes, which no doubt the farmers 
will prove, when they become desirous of availing themselves of 
that essential material for the highest and permanent improve- 
ment of their soil. It is not improbable also, that future observa- 
tions may lead to the discovery of purer beds in those particular 
counties, though it is not probable, that any great abundance will 
be found, as it is wanting altogether in the succeeding rocks in 
Pennsylvania; and those great masses of limestone, common to 
the more northern counties, should they extend so far south, 
must be at a very low level, or be replaced by the sandstone or 
shale. Of all the marine fossiliferous rocks of New-York com- 
posed of limestone, one only makes its appearance to the east of the 
anthracite coal of Pennsylvania. It is found from the Delaware 
to the Schuylkill, and between the Blue ridge and the line of the 
axis of the sharp mountain. That line being the eastern boundary 
of the anthracite coal. The direction of all those same limestones 
of New-York is south, increasing in thickness going west, dimi- 
nishing correspondingly in the opposite direction, so as to disap- 
pear amongst the sandstone and shales. 
The impure limestones of the frontier counties abound in ma- 
rine shells, and other organic remains, affording characters to the 
series to which they belong. Sometimes the shells form the only 
calcareous material. In many instances by exposure to the air, or 
in other words, to atmospheric agents, or where the rock freely 
admitted the passage of water, the shells have been wholly remov- 
ed, leaving cavities corresponding with the forms possessed. The 
carbonate of lime so removed, has given origin to the honeycomb 
limestone, or calcareous tufa, of which many well known locali- 
ties exist. In some localities the process is going on; in other 
and the greater number, it has long since come to an end. This 
tufa is exceedingly tough, and strongly resembles the travertin© of 
Rome, celebrated from being the chief material of which the an- 
cient monuments of that city were built. 
It is not improbable also, that the shell marl, so frequently co- 
vering the bottoms of many of the smaller lakes of New-York, 
may have had a similar origin, but deposited in water, the water pre- 
venting the cohesion of its particles. The marl near Cortland 
Four Corners is put into the form of bricks, dried and burnt into 
lime. Some of it no doubt may be pure enough to manufacture 
