No. 275.] 
m 
The slate and limestone glazed with anthracite, and presenting many' 
points of resemblance to anthracite coal, are sufficient to excuse the con- 
clusions of those who have supposed the existence of workable coal 
beds, and who did not know that such deposits have not been found in 
primitive rocks. 
VI. LIMESTONE. 
This rock is abundant, and extensively distributed in the counties of 
New- York, Westchester and Putnam. It is all associated with primi- 
tive rocks, such as gneiss, mica and talcose slates, and with granite, and 
is interstratified or embraced as beds in these rocks. In colour it varies 
through white, gray and clouded to black; in texture it is coarsely crys- 
talline, granular, and perfectly compact: in composition, it varies from 
pure carbonate of lime to magnesian and ferromagnesian carbonate of 
lime, wiih variable quantities of earthy impurities: in hardness, from a 
very strong stone to one so friable as to be capable of being crushed to 
sand by pressure in the hand. 
This rock is of greater present as well as prospective value in the re- 
gion of country where it is found, than any other, unless it be the gra- 
nite, which may, in progress of time, become equally valuable. 
Limestone of MeW' York County^ 
This rock abounds in the north part of the island, and has been quar- 
ried to a considerable extent for marble, building stone, and for lime. 
The details of this rock in New- York county will be found in the de- 
scriptive geology of that county by Prof. Gale, in the appendix to this 
report. 
Limestone of Westchester and Putnam Counties, 
The limestone of these counties has the same dip and line of bearing 
as the contiguous gneiss and gneissoid rocks, and like them, is distinct- 
ly stratified. They all dip to the ESE, (as a general rule, but there 
are local exceptions,) at a high angle, varying from 45° to 90°. The 
limestone forms several nearly parallel ranges at intervals of to three or 
four miles apart, ranging in a NNE and SSW direction. 
1st. The most eastwardly deposit of this kind, and of any great mag- 
nitude, is seen on Gouverneur Morris's farm, opposite Harlaem, where 
it is quarried for making the piers for the rail-road bridge and for other 
purposes. It is generally gray, and in some places is much intermixed 
with mica. Many of the blocks, and even the rocks in place in the 
[Assem. No. 275. | 12 
