¢ 
492 [May 16, 
Claypole.} 
from navigating the former. As to the reason why such a memento 
should be left of the visit, of course no definite answer can be given, 
but it is a fact well known that memorials were often made or erected, 
engraved or placed at localities where events had taken place, and the 
address of the chieftain to the men may have been of some noteworthy 
matter, perhaps even to commemorate the fact of having landed at that, 
spot. 
In conclusion, I would say, that the circumstances are worthy of con- 
sideration, if not absolutely convincing. 
On the Clinton and other Shales, &e., composing the Fifth Group of Rogers 
in the First Survey of Pennsylwania. By Prof. #. W. Claypole. 
(Read before the American Philosophical Society, March 21, 1884.) 
This group has been the field for considerable discussion in regard to 
the proper place of its different beds when compared with those supposed 
to be of similar or nearly similar age in New York. It has not been easy 
to prove where one formation began and another ended. By throwing all 
those shales into a single group Prof. Rogers avoided discussion on this 
point and No. 5 became a local or Pennsylvanian term, The group has 
the merit of being a very natural one regarded from a physical standpoint, 
Based on the massive Medina sandstone, and capped by the conspicuous 
Lewistown limestone, there was no question of its physical limits in the 
State, and all further. differentiation was postponed. 
But with the advance of geology, the necessity arises for closer com- 
parison and correlation. It is not enough to suppose that the fifth group 
of Rogers corresponds with the New York beds between the top of the 
Medina sandstone, and the Lewistown or Lower Helderberg limestone. 
More exact division and definition are desirable, and my recent work in 
Perry county has put into my hands the means of examining this question 
in a new method—by the means of the fossils. Palaeontology has hitherto 
done little towards its solution, and by paleontology alone in many cases 
can the true solution be reached. 
In the present paper I propose to examine these rocks constituting the 
fifth group of Rogers, and to set forth the evidence thus far attainable, 
both stratigraphical and paleontological, for the places assigned to them 
among the paleozoic rocks. 
Tum OLINTON GROUP. 
Beginning at the top of the Medina sandstone regarding the age of 
which there has been no question I will consider first the beds lying upon 
it in Perry county. These are shown in the following section : 
