248 
[Assembly 
The Shawangunk grit rock has been called " mill-stone grit," by- 
Professor Eaton ; and it well deserves the name, both from its uses, 
and its similarity in texture and mineral composition, to the mill-stone 
grit of England ; but as it has a different position, in the geological series, 
from that rock, which has now become a term indicating a conglome- 
rate grit in a particular geological position, I have thought it better to 
use a local term for this formation, viz : Shawangunk grit. 
Economical applications and mines. 
The useful applications of the Shawangunk grits are not numerous. 
They are, for mill- stones, building stones and glass. 
The firm, coarse grits, have been long quarried for mill-stones, and 
have been extensively used. They are known in market by the name 
of Esopiis millstones.^ They are still quarried to a small extent, but 
since the French buhr stone has been brought into common use for 
mill-stones, the Esopus stones are in less demand. Many small mill- 
stones, for family use, in grinding corn among the planters of the 
southern States, are still manufactured and sent to market. 
The finer white and gray grits, which frequently resemble granular 
quartz, are well adapted for the manufacture of glass, and it is believ- 
ed that the glass factory at Ellenville, Ulster county, makes use of this 
material. I know it was in contemplation to do so at the time of its 
erection. 
These fine grits would make a beautiful and durable building ma- 
terial, which is as easily dressed as the common granites. Localities 
were seen, within less than two miles of the canal, where blocks could 
be procured three to five feet thick, and five to twenty feet in their oth- 
er dimensions, without a seam, and on which the weather has produc- 
ed no perceptible effect, during the ages through which they have been 
exposed. Such rock as this, the engineer may use without fear of ha- 
zarding his reputation ; and his employer may feel certain that the 
structures built of it will not crumble down by the ordinary action of 
the weather in a few years, like some of our public works and private 
dwellings. 
* Esopus was the name of the township and village of Kingston, during the war 
of the revolution; and as these stones were quarried at no great distance, and 
were shipped from that vicinity, they have acquired the name of Esopus mill-stones. 
Esopus is now the name of a township and village a few miles south of Kingston. 
