CHEMUNG GROUP. 
277 
in greatest force ; and from this early thinning in a westerly direction, as well as from other 
facts, it is evident that it had not the same origin as the rock below. 
In examining rocks westward, the place of this never presents any remaining matter that 
indicates its former existence, or any marks by which we can infer that it has been previously 
swept off. In many places the conglomerate rests upon the Chemung group, without the 
intervention of any other rock. 
The rocks of the New-York system, although many of them diminish westward, are most 
or nearly all of them represented as far as the Mississippi river. The change, for the most 
part, is well marked in all cases between them and the higher rocks, and they as evidently 
constitute one great system over all this extent of country. 
It may not be out of place here to remark, that the rocks of the Chemung group are 
regarded by some geologists as forming a part of the Old Red sandstone, and that the 
“ Devonian system ” of Mr Phillips includes both these rocks and the red sandstone which 
succeeds them. I have already remarked, that in the eastern part of New-York, there are 
many fossils typical of lower rocks which extend upwards into the Chemung group ; and 
should the latter be united to the Old Red, it offers too intimate an association of strata, and 
of organic remains, to allow of any separation beyond that of simple groups; whereas by 
leaving the Chemung united to the rocks below, we have a very marked change in the 
productions of the succeeding formation. 
