532 CHARLES S. PROSSER 



I do not believe that the Pennsylvania subdivisions can be made out west 

 of Ashtabula and Trumbull, or even that they are well marked on the high- 

 land west of the Grand River, in those counties. Here in Cuyahoga the shales 

 between the Berea and the conglomerate show only a twofold lithological 

 division, to the best of my knowledge, and the boundary occurs about half 

 way up. The lower half consists of soft, blue-black, clay shales with a few 

 local flags, especially toward the base. On top of these comes a flaggy 

 horizon, at what I take to be the Sharpsville level, followed by alternating 



shales and concretionary layers, with some flags The basal shales 



are sparingly fossiliferous, a big Orbictiloidea most abundant, and impressing 

 a layman as being a Sunbury fauna in depauperate condition. The flags and 

 following shales hold a numerous fauna, pyritized and badly preserved in the 

 flags, excellently preserved in the concretions, which form definite bands.' 



Again in southern Ohio, in the Ohio River section, below and 

 above Portsmouth, succeeding the top of the Sunbury shale, 

 which is a very conspicuously marked horizon, it is a matter of 

 some difficulty to divide the remaining Waverly rocks into the 

 formations which are so clearly marked lithologically in central 

 Ohio. 



12. The formations from Nos. 14 to 19, inclusive, form the 

 Waverly series. For a revision of the classification of this series 

 see a paper by Prosser in Journal of Geology, Vol. IX (i 901), pp. 

 205-32 ; and for an extended discussion of the Sunbury shale, 

 ibid., Vol. X (1902), pp. 262-313. 



13. The line of division between the Carboniferous and 

 Devonian systems is in doubt, as indicated by the dotted line 

 on the chart. In recent years it has generally been drawn at 

 the base of the Bedford shale, but Professor C. L. Herrick has 

 indicated the line as high as the lower part of the Black Hand 

 formation, or perhaps even higher.^ Dr. I. C. White writes me 

 as follows concerning this point : 



The red Bedford shale is undoubtedly of Catskill age, as is also the 

 Berea sandstone and its overlying shale (I think), since it becomes ri?^ in 

 passing eastward. If you mean to class the Catskill as Carboniferous, then 

 your division is correctly drawn, but if you think the Catskill is Devonian, 

 then the Carboniferous line should be drawn at the base of the Cuyahoga. 

 I am non-committal on the general question as to whether we should include 



' Letter of April 2, 1903. 



= Bull. Den. Univ., Vol. IV (1888), pp. 100, 106. 



