NOMENCLATURE OF THE OHIO FORMATIONS 527 



Lesley, but on its first publication in 1877 it is distinctly stated 

 by both Ashburner ' and Franklin Piatt ^ that it is "proposed 

 by the present State Geologist of Pennsylvania," and the follow- 

 ing year Professor Stevenson mentioned Professor Lesley's name 

 in crediting the authorship of the formation. 3 In the Ohio 

 reports this formation has generally been termed the "Con- 

 glomerate group," although Dr. L C. White as early as 1881 

 applied the name " PottsviUe conglomerate" to the continuation 

 of these rocks across the state line in Crawford county, Pennsyl- 

 vania. Certain geologists, however, have thought that these 

 rocks of Ohio and western Pennsylvania represented a longer 

 time interval than the typical PottsviUe conglomerate of eastern 

 Pennsylvania, and hence it has appeared doubtful whether the 

 name "PottsviUe" should be applied to the Ohio formation. 

 At the base of the formation in northern Ohio is a conglomerate 

 or coarse grained sandstone which has generally been called the 

 "Sharon conglomerate," and is perhaps equivalent to the Olean 

 conglomerate of southwestern New York. Regarding the strati- 

 graphic position of this latter conglomerate Dr. J. M. Clarke 

 has written me as follows : 



It may interest you to know with regard to the Carboniferous horizons 

 that .... Messrs. David White and Campbell have been over the field in 

 Cattaraugus county, and they have convinced themselves that there is no 

 longer any question of the PottsviUe age of the Olean. This determination 

 seems to be based largely on the evidence of fossil plants.'* 



This conclusion agrees with the statement of Mr. M. R. Campbell, 

 apparently based upon the investigations of Dr. David White, 

 regarding the age of the Sharon conglomerate of western Penn- 

 sylvania. Mr. Campbell says : 



From the evidence afforded by fossil plants, Mr. White proves con- 

 clusively that about the beginning of the PottsviUe epoch an uplift occurred, 

 which affected much of the Mississippi Valley. A large land area was formed 

 that extended as far east as the Broad Top Basin and the Northern Anthracite 

 field. This land area persisted until at least 600 feet of PottsviUe sediments 

 were deposited in the southern Anthracite basin. A subsidence then occurred 



^ Proc. Amer. Phil. Soc, Vol. XVI, p. 533. -^ Ibid., K3, 1S78, p. 12. 



^Second Geol. Surv. Pa., H^, p. xxvi. -t Letter of April 30, 1903. 



