351 
COMPOSITION OF LIMESTONES, 
XIII. A SERIES OF TABLES, SHOWING THE COMPOSITION OF THE LIME¬ 
STONES, SHALES, SLATES AND MARLS OF NEW-YORK; 
TOGETHER WITH REMARKS WHICH ARE DESIGNED TO SHOW THEIR PROBABLE INFLUENCE UPON THE 
COMPOSITION OF THE SOILS IN CONNEXION WITH THEM. 
Limestones of new-york. 
The geological formations embraced in the limits of the State, contain deposits of this 
rock. 'The superior part of the Silurian system, and the Old Red or Devonian of recent 
authors, are quite deficient in limestones, as has been already stated in the foregoing pages. 
The Primary system, however, is rich in limestone ; but its qualities are usually defective, 
in consequence of its containing insoluble matter, as silica or quartz, mica, pyroxene, 
hornblende, etc. In the specimen of which I have given an analysis, which was taken 
from the beds in gneiss at the Natural bridge, Jefferson county, scarcely a trace of magnesia 
Avas found. This was an unexpected result, inasmuch as it is often associated with ser¬ 
pentine and other magnesian minerals. It may have happened that wherever magnesia 
and the other necessary elements were contained in the rock, they have been converted 
into serpentine, and the serpentine itself has been separated from the mass of limestone 
by segregation. The beds of primary limestone require no farther notice, as they have 
been fully described already. 
The Taconic limestones are frequently magnesian, or dolomitic, as they have been 
called ; and from my oavii examinations, I believe that all the beds which contain tremolite 
are magnesian. It appears, however, from the lamented Olmsted’s analyses for the Ver¬ 
mont survey, that many of the friable limestones of this system are nearly pure carbonates 
of lime, and are destitute of magnesia. 
The Sparry limestone was also found to be destitute of magnesia, at least so far as the 
specimen examined was concerned. 
The limestones at the base of the Silurian system are quite magnesian, especially the 
Calciferous sandstone, and parts at least of the Trenton limestone. The Birdseye, and the 
Isle Lamotte marble, appear to be destitute again of magnesia, the latter containing only 
3 or 4 per cent. 
The Niagara limestone of the Ontario division can scarcely be called magnesian. The 
shales below contain some magnesia and soda; the latter, as it appears from the decom¬ 
posing materials which are located in favorable spots, exists in large proportion. 
The limestones become magnesian again in the lower part of the Heidelberg division, 
especially the water limes. Magnesia is contained in the slaty thin-bedded, as well as in 
the thick-bedded limestones. 
The Onondaga limestone is a pure limestone, or, in other Avoids, is not magnesian. 
The limestone of the Marcellus slate, as it occurs at Schoharie, Cherryvalley and Man¬ 
lius, is probably magnesian : it has not been examined for this substance. 
