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J. J. Stevenson—Upper Devonian Rocks of Pennsylvania. 428 
Art. LXI.—TZhe Upper Devonian Rocks of Southwest Pennsyl- 
vania ; by JoHN J. SrEVENSON, Professor of Geology in 
the University of New York. 
TuE Vespertine or Pocono sandstone of the Pennsylvania 
Survey is a massive sandstone from 350 to 450 feet thick in 
stones, interstratified with red to gray and olive shales. 
representing the Upper Devonian. During the hasty examina- 
tion of 1876, I was unable to make any close study of the sec- 
tion, and so provisionally regarded the lower rocks as belonging 
to the same series with the upper. i 
in my report to Professor Lesley for 1876. But the examina- 
tions made in the several gaps during 1877 showed the previous 
conclusion to be erroneous, and that the lower portion of the 
section from the very base of the Pocono sandstone is Devonian 
and not Lower Carboniferous. : 
A general section of the Devonian rocks, as observed in the 
gaps mentioned above, is as follows :— 
1. Shales and thin sandstones--.. --- ---------- 
2. White to BRET aot sandstones with some shale--. 70 “ 
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