522 CHARLES S. PROSSER 



NOTES ON THE GEOLOGICAL SCALE OF OHIO. 



1. The glacial formations of Ohio have recently been very 

 fully described by Mr. Frank Leverett, to which account the 

 readers interested in these deposits are referred.' 



2. The thickness assigned to the various formations is fre- 

 quently that given in the last volumes of the Geological Survey 

 of Ohio or other late reports of Dr. Orton. Changes have been 

 made in stating the thickness of certain formations based upon 

 data secured by the writer or upon trustworthy statements of 

 other authors. The thickness, however, of most of the formations 

 differs so greatly in different sections that it is almost impossible 

 to make general statements which will apply throughout the 

 state. This variation is often indicated by giving the thickness 

 as ranging from and to a certain number; as, for example, the 

 glacial drift is given as from to 550 feet in thickness. 



3. In 1880 Professors William M. Fontaine and I. C. White 

 described the flora of the Upper Barren Coal-measures of West 

 Virginia and southwestern Pennsylvania, and stated : 



To sum up finally the evidence derived from all sources, we find our- 

 selves irresistibly impelled to the conclusion, that the .... Upper Barrens 

 of the Appalachian Coal Fields are of Permian age. ^ 



The fauna of these rocks is very small and does not afford 

 any conclusive evidence as to their age, but the flora has recently 

 been re-examined by Dr. David White, who corroborates the 

 earlier conclusions of Fontaine and I. C. White. Dr. David 

 White writes : 



Recent collecting materially increases the Permian evidence, and seems 

 to leave little room for doubt that the beds in and above the Washington 

 limestone are referable to the Lower Rothliegende of western Europe. The 

 data so far obtained from the lower beds of the Dunkard are, in the judgment 

 of the writer, not yet conclusive as to Permian age.^ 



The Rothliegende is the older division of the Permian of 

 western Europe, which is found typically in Germany. The 

 lower Washington limestone occurs in the lower part of the 

 Dunkard formation and at the typical locality at Washington in 



' U. S. Geol. Surv., Monograph XLI, IQ02. 



^Second Geol. Surv. Pa., PP., p. 1 19. 



^Science, N. S., Vol. XVII (February 20, 1903), p. 298. 



