452 
[Assembly 
only require a little more capital, and better means of communication, 
to become the abodes of plenty and contentment. 
The following is a table of the rocks of Western New- York, in the 
order of succession, with their reference to the subdivisions of the " Si- 
lurean System." In most cases, the limits of these subdivisions are 
clearly ascertained, but it must be recollected that the Onondaga Sali- 
feroas group, or that mass containing all the plaster beds of the fourth 
District, appears to be wanting as a member of the Silurean system in 
England and Wales. The limestones of the Helderbergh and Scho- 
harie accord better with the description of the Wenlock or Dudley 
limestone, than those of Western New-York, the latter being much 
thinner. 
The Lockport limestone is evidently referable to the Dudley period, 
♦and so also are the Onondaga and Seneca limestones ; consequently 
the saliferous group lying between these will be included in the group. 
The former of these limestones contains many fossils which are com- 
mon to the Wenlock limestone, and at one locality in Monroe county 
specimens were collected containing great numbers of a small species 
of Orthis which occurs at Dudley, the specimens from both localities 
closely resembling each other, and each highly charged with the same 
fossil. 
The table exhibits the arrangement so far as the limits of the groups 
have been ascertained, but the groups of the Silurean System" do 
not well accord with the natural divisions of the rocks in New- York. 
Old Red Sandstone. | Old Red Sandstone. 
Chemumg Group. 
Gardeau and Portage Groups. 
Ithaca Group. flipper Ludlow Rocks. 
Cashaqua Shale. 
Moscow Shale. 
Lower Ludlow Rocks 
Ludlow ville Shale. 
Calcareous blue Shale. 
Dark olive Shale. 
Marcel] us Shale. 
Seneca Limestone. 
Onondaga Limestone. 
Oriskany Sandstone. I w i i t • 
Hydraulic Limestone ^Wenlock Limestone. 
Onondaga Saliferous Group. 
Lockport Limestone. 
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