4 
16 Hall on the Strata and Organic Remains 
seen throughout the whole of western New York and in Ohio, 
as far as the western limit of the Alleghany Coal Basin. After 
taking up the same line of observation where these rocks re- 
appear in Indiana, we find the following arrangement. 
The rocks of the Chemung Group are succeeded by fine, 
gray argillaceous sandstone, which contains intercalated beds 
of oólitic limestone, with fossils entirely different from any at — 
the east. ‘This sandstone passes upwards and is succeeded by — 
a limestone differing essentially from any limestone below it, - 
and holding a place which presents no rock of this kind at the 
east. Succeeding this limestone we have the same conglom- - 
erate, which in New York, some parts of Pennsylvania, and in 
the eastern part of Ohio, rests upon the Chemung Group. 
During one period in the eastern part of this ocean, while | 
the Old Red Sandstone was being deposited, there is apparently 
no equivalent deposit in the west, unless the gray sandstone and — 
oölitic limestone are its Si Should this prove to be - 
true, on farther examination, (and I have lalsdiyubt of it) : 
then we have a more gradual passage and int of 
produets in the passage of the Old Red, or even from the ibo. 3 
mung Group of New York to the Carboniferous period than — 
from the Chemung to the Old Red as it appears in New York. — 
Again, in the western part of this ocean, was accumulated 4 
that immense deposit of limestone, occupying so much of the — 
Mississippi valley, during which period there was no deposi- : 
tion of importance at the east, and during both these periods a 
large portion of surface appears to have received no deposit _ 
at all. 5 
We have, then, the lower inne of the Great Coal Foe 
mation resting in one place upon the Chemung Group, again — 
upon the Old Red Sa ndstone , and finally upon the Limestone, - 
which underlies the great cond basin of Illinois. What may — 
have been all the operating influences it is perhaps ee 3 
to say, but such are some of the facts. * 
- It will be perceived that, with a single exception, all the- 
mechanical deposits diminish in a — Seeiee while |. 
AED. Ls 
