SHALES AND SLATES. 
355 
The Tully limestone is also destitute of magnesia, but is an impure limestone, and, in 
many respects, is well adapted to the formation of lime for agricultural purposes. This is 
the last and highest limestone in New-York. 
The freshwater marls show some variation in composition, and they contain very little 
magnesia. Animal and vegetable matter, a trace of alumina and iron, form the principal 
impurities of the marls. Many are extremely valuable for lime, and may be as cheaply 
burned as the solid limestones. The lime is pure arid snow white, and is excellent for 
whitewashing. 
TABLE SHOWING THE COMPOSITION OF SEVERAL LIMESTONES IN NEW-YORK. 
NAMES OF LIMESTONES. 
Insoluble 
matter, 
silica, &c. 
1 Alumina and 
peroxide of 
iron. 
Carbonate 
of lime. 
Magnesia. 
Phosphate 
of lime. 
Potash. 
Soda. 
Manganese. 
Water and 
loss. 
Soluble • 
silica. 
Calciferous sandstone... 
6-20 
4-50 
58-86 
27-20 
1-62 
Chazy limestone. 
27-62 
18-03 
49-00 
3-60 
1-74 
. . 
Trenton limestone*. 
15-60 
4-18 
52-76 
24-87 
1-19 
Niagara limestone. 
0-68 
4-24 
93-40 
4-68 
Septariat... 
15-24 
11-50 
73-24 
trace. 
Onondaga limestone .... 
3-74 
0-18 
89-00 
4-00 
0-03 
3-02 
Tully limestone. 
27-61 
10-34 
54-10 
0-34 
0-88 
1-80 
trace. 
4-93 
trace. 
Sparry limestone. 
7-40 
1-60 
91-00 
Stockbridge limestone}: . 
0-29 
. . 
99-51 
trace. 
0-20 
Dolomite . 
, . 
7-70 
60-20 
33-01 
Primary limestone||. 
0-8S 
0-88 
98-24 
Black marble (Lamotte)} 
4-80 
2-60 
87-94 
4-56 
trace. 
Swanton marble}:. 
2-31 
1-09 
94-66 
0-23 
* Plattsburgh; slaty, f From the Marcellus slate. ^ Statuary marble by Olmsted, of Brandon, Yt J| Natural bridge, Jefferson county. 
Slates and shales of new-york. 
As the slates and shales may be employed, under favorable circumstances, as fertilizers, 
and as they decompose by the action of the weather, rains and frosts, it seemed proper to 
ascertain their composition. Some of them have a wide distribution, and maintain a 
uniformity of lithological character, and probably of composition also. 
The slates which are widely distributed, are the taconic and roofing slates. These pass 
through New-York from north to south, or in a direction nearly parallel with the Hudson 
river, which they cross obliquely above the Highlands. They continue through Orange 
county, and then pursuing nearly the same direction, traverse several of the States, in the 
range of their strikes. 
The slates and shales of the Salt group are comparatively local, but they have an im¬ 
portant influence on the soils of Central and Western New-York. 
The Marcellus slate is often highly calcareous, and may then be employed as a fertilizer. 
The Cortlandville shale probably represents the composition of a large mass of the rocks 
above the Tully limestone. 
How far, and with what success, the rocks, particularly the slates which contain alkalies, 
may be used with ultimate benefit as fertilizers, may be judged of, when it is stated that 
45* 
