64 F 2 . REPORT OF PROGRESS. E. W. CLAYPOLE. 



limestone of surrounding districts. Apparently, too, the 

 black Marcellus shale is thinner than in many other parts 

 of Pennsylvania — a fact quite in harmony with the above 

 suggestion. 



We may possibly, therefore, have in the interval and gap 

 between the Oriskany Sandstone and the Marcellus a second 

 dry land area in Perry county considerably later than that 

 described in the report on Rye township. 



No. VIII a. Upper Helderberg (Corniferous) group. 



The Upper Helderberg or Corniferous Group being, as 

 above mentioned, absent over the whole county, the lowest 

 of the Hamilton rocks rest directly in most places upon 

 the Oriskany Sandstone. For the reasons which have led 

 to the adoption of this opinion the reader is referred to the 

 report on Madison township. 



No. VIII b. Marcellus limestone and black shale. 



Overlying the Oriskany sandstone is a series of shales 

 and limestones which palseontological evidence places in the 

 Marcellus division of the Hamilton group. They are all 

 constant, except in the southeast, but vary in thickness at 

 different outcrops in the county. The lower portion of this 

 series has been regarded as the representative of the Cornif- 

 erous limestone of New York, but my observations decide 

 against this identification. 



The Marcellus beds in Perry county may be thus divided : 



5. Marcellus Black Shale, 100 feet ^ 



4. Marcellus upper iron ore, 2 " 



3. Marcellus Limestone, 50 " \ 204 



2. Marcellus Lime Shales, 50 •« 



1. Marcellus lower iron ore, 2 " J 



Oriskany Sandstone. 



1. The lower iron ore is of little value ; it has been dug 

 for paint in one or two places but is worthless as an ore. 

 (See chapter on iron ores.) 



2. Marcellus Lime Shales. This bed is of very uniform 

 thickness wherever it appears throughout the county. It 

 consists of thin beds of a very argillaceous gray limestone 

 and of shale of the same color. In most parts of the county 



