" 
of the Older Formations of the United States. — 5 
The same fossils which typify these limestones in New York 
are likewise found in Kentucky and near the mouth of the Wis- 
consin River. The large Orthocerus, and some other shells from 
the latter place cannot be distinguished from those of New York, 
and if we may credit the observations, made many hundred 
miles to the northward of this place, similar fossils are equally 
typical of the strata. In this instance, therefore, we find a 
uniform composition or material over an extensively wide area, 
with little apparent difference in the degree of development, 
and the same association of organic remains. In this instance, 
therefore, we are forced to admit a very uniform condition in 
the depth and character of bottom of this primeval ocean. 
What facts would appear from an examination farther south 
and west we cannot infer, but we already know that there is 
sufficient width from north to south to disprove any inference 
that this great east and west extent was merely the margin of 
an ocean. The strata extend northward from New York far 
into Canada, and from the eastern part of that province stretch 
westward over a great breadth of country on the north of Lake 
Ontario. Again they appear in an isolated patch in Kentucky 
and in Tennessee; while in Virginia and Pennsylvania, as 
shown from the Reports of Professors W. B. and H. D. Rogers, 
they form a broad belt upon the eastern margin of the sedi- 
mentary formations, thus proving uniform conditions over this 
wide ocean. Many species of fossils, which in New York are 
regarded as typical of the lower limestones, are found both 
i.m Pennsylvania and Virginia, accompanying the same strata. 
= » The next group which we have to consider, occurs in. New 
.. the line of section westward we find these rocks ario in 
. Ohio, but with some change in their lithological features. The 
prevailing character here, and also in Indiana, Kentucky, and 
on the praes s River above Dubuque, is that of a calcareous 
aggregation of strata, with interstratified marl, and more rarely 
T impure pii e, The whole of this group, together with the 
