+ 
62 Notes upon the Geology of the Western States. 
The result shews very clearly that there are two great lime- 
stone formations occupying the valley of the Mississippi, and 
that the lead~bearing limestone is not the same as that immedi- 
ately underlying the coal formation.* In some places, both these 
limestones are very similar, and in the absence of the neighbor- 
ing rocks or fossils, might be mistaken without careful observa- 
tion. Both are often light colored, a fact which is common to 
nearly all the western rocks as compared with those of New York. 
From the light color and mingoerintes ohataater of the Niagara 
limestone, it has been s holding the place 
of the magnesian limestone of Europe, the true posing: of so 
is known to be above the coal formation. Sipartliet 
-'The facts here stated show a great diminution, first of inte 
matter, and next of shale, as we go westward, and in the whole, 
a great increase of calcareous matter in the same direction. A 
large portion of that mass known as Medina sandstone is shale, 
and in New York is of great thickness, while it has entirely dis- 
appeared westward. ‘The Onondaga salt group, essentially a 
clayey or shaly one, is in its greatest force in central New York, 
while it is entirely wanting westward. The fossiliferous shales 
of the Ludlowville group, as already stated, are at the falls of the 
Ohio, represented by a little more than one hundred feet, and far- 
ther west by still less. Again, all those of the Gardeau, Portage, 
and Chemung groups, seem almost obliterated and to give place 
to an enormous mass of limestone, which goes on ss 
westward as far as known. wh 
~The name “cliff limestone,” of Prof. Locke, is very sire 
priate for what I have here termed the Niagara limestone, so far 
as the western part of Ohio and part of Indiana are concerned, 
and I own that after examining these districts I was much grati- 
fied with the name. But after seeing a limestone much higher 
in the series already described, forming cliffs for several hundred 
miles along the Mississippi, the name seems of doubtful propriety: 
The name “scar” or cliff limestone of English authors, is ap 
plied to one much higher in the series than that alluded to, so 
that.the name having once been used for another rock, seas 
its adoption for this post at ie = 
Albany; Copies a ies ower wy 
a, 
=a <casgoratntia 
* The lead Deering rock of ‘Missonri i is a different ‘one from that of Iowa, Wis- 
consin, and Illin 
