NOMENCLATURE OF THE OHIO FORMATIONS 523 



southwestern Pennsylvania, 1 1 7 feet above the top of the Waynes- 

 burg coal or base of the Dunkard formation. A number of the 

 European geologists have accepted Permian as the age of the 

 Dunkard formation, and Dr. Freeh states that the Dunkard 

 Creek beds and Cassville plant shale, the latter of which is the 

 shale at the base of the Dunkard formation immediately over- 

 lying the Waynesburg coal, are the equivalent of the Kusel stage, 

 which is the oldest- formation of the Lower Rothliegende of 

 Germany. And in another sentence is the statement that the 

 petrographical and paleontological similarity of the Dunkard with 

 the Rothliegende of western Europe is therefore beyond doubt.' 



4. The formation was named the "Dunkard Creek series" on 

 account of the fine exposures found for thirty miles along the 

 banks and bluffs of this stream, which flows along the West 

 Virginia- Pennsylvania line;^ later, with Dr. White's sanction, 

 the name was shortened to the " Dunkard formation," thus 

 bringing it in harmony with the terms now usually selected for 

 the names of formations. ^ On the scale below the accepted name 

 for this formation is given in parenthesis "Upper Barren Coal- 

 measures," the name which has generally been used for this 

 formation in the Ohio reports. The corresponding name which 

 has been used in the Ohio reports for the three succeeding 

 formations is given in the same manner. 



5. The top of the Waynesburg coal, or its horizon, and the 

 base of the Pittsburg coal mark the top and bottom of the 

 Monongahela formation. 



6. Franklin Piatt applied this name to the " Middle Barren 

 Measures" and "Mahoning sandstone" in his "Column of 

 Palaeozoic formations," but failed to define it more precisely.* 

 Later the name was defined and used for this formation in 

 Maryland, s 



'^Lethaea geognostica, Th. I; Lethaea palaeozoica, Bd. II, Lief. 3 (1901), p. 546. 



"^ Bull. U. S. Geol. Surv., No. 65, pp. 19, 20. 



30'Harra, Maryland Geol. Surv., Allegany Cotmiy, 1900, pp. 86, 128; and 

 Prosser, Jour. Geol., Vol. IX (1901), p. 428. 



^Second Geol. Surv. of Pa., H, p. 8. 



sO'Harra, Maryland Geol. Surv., Allegany County, 1900, pp. 86, 118; and 

 Prosser, Jour. Geol., Vol. IX (1901), p. 426. 



