58 Notes upon the Geology of the Western States. 
ward, only two or three of its members being amen at 
the Niagara river. © 
The second or “ Onondaga salt group,” is im phedtaut Gas 
about the central part of New York, being about one thousand 
feet thick, consisting mostly of shales and marls containing the 
gypsum beds, and all the important salt springs of the state. In 
the eastern part of the state it is nearly lost from thinning out, but | 
westerly it suffers but tittle diminution as far as the Niagara river. a 
The Niagara limestone and its accompanying shale, are we 
scarcely recognized in the eastern part of New York, and even ta 
as far west as the centre, they form only masses of a few feet in 3 
thickness. "The whole however gradually increases westward, = 
and on the Niagara river, as well as at Lockport, the two masses ‘Sal 
are’ niot less than two hundred feet thick. + 5 
_ These three groups are traced far into Canada with little vari- 
ation, except that the Niagara limestone becomes thicker and the 
shale more calcareous. The line of outerop or strike of this 
limestone is from Rochester westward, along a terrace known as 
the mountain ridge and which extends by Lewiston and Queens- 
ton into Canada, and is rey traced icon as the ee ‘of 
Lake Ontario. 
Near the western ena of Lake Erie the Niagara linvéstOone 
appears above the surface of the water, having been elevated, 
and forms a continuation of the axis before alluded to, as extend- 
ing from Lake Erie to the S. W., along the borders of Ohio and 
Indiana. In the central and western parts of Ohio it is the most 
important rock, and is designated the “cliff limestone” by Prof. 
Locke. Among its numerous localities may be named Spring- 
field, Dayton, the vicinity of Columbus, and several places in 
Adams county. In Kentucky, at Louisville, and the falls of the | 
Ohio, at Madison and other places in anrepste it appears as wand | 
limestone of greatest thickness. 
» In examining the upper part of the “ cliff. sinanene” I “lt 
it, so far as lithological characters are concerned, a continuation 
of the Helderberg group, the Onondaga salt fornistiein having 
thinned out almost entirely, having in fact no representative ex- 4 
cept a thin layer. of water-lime, which is seen at the falls of the 
Ohio and the canal canal below. Louisville, but in other localities is of 
less i fen scarcely to be recognized. We have 
here then this ‘condition of things~the Niagara limestone, 
