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 lliey 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 and snow white, and is excellent for 

 whitewashing. 



TABLE SHOWING THE COMPOSITION OF SEVERAL LIMESTONES IN NEW-YORK. 



NAMES OF LIMESTONES. 



12 = 



3 o 



s 



2 S 



Calciferous sandstone... 



Chazy limestone 



Trenton limestone* 



Niagara limestone 



Septariaf 



Onondaga limestone .... 



Tully limestone 



Sparry limestone 



Stockbridge limestoncf . 



Dolomite 



Primary limestone|| 



Black marble (Lamotte){ 

 Swanton marble^ 



6- 20 

 27 • 62 

 15-00 



0-OS 

 15 -2-1 



3-74 

 27'61 



7-10 



U • 2'J 



o's'- 



4-80 

 2 -.3;: 



4-50 

 lS-03 



4-18 



4-24 

 11-50 



0-18 

 1U-.34 



I -(50 



7-71) 

 0-S8 

 2-00 



i-o;- 



5S-S0 

 49-00 

 52-76 

 93-40 

 73-24 

 89-00 

 54-10 

 91-00 

 99 -5i 

 00-20 

 9S-24 

 87-94 

 94-OCi 



27-20 



3-00 



24-87 



trace. 

 4-00 

 0-34 



0-03 

 0-88 



1 -80 trace. 



trace. 



0-20 



* PlalLsburgh ; slaty, f From the Marcellui slate, f Statuary marble, by Olmsted, of Brandon, Vt, j| Natural bridge, Jefferson county- 



Slates and shales of new-york. 



As the slates and sliales may be employed, under favorable circumstances, as fertilizers, 

 and as they decompose bj' the action of the weather, rains and frosts, it seemed proper to 

 ascertain their composition. Some of thorn have a wide distriluition, and maintain a 

 uniformity' of lithological character, and probably of composition also. 



The slates wliich are widely distributed, are the laconic and roofing slates. These pass 

 through New-York from nortli to south, or in a direction nearly parallel with the Hudson 

 river, which they cross obliquely above the Highlands. They continue througlt 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 Cortlandvillc 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 llie slates which contain alkalies, 

 may be used with ultimate benefit as fertilizers, may be judged of, when it is stated that 



4ri* 



