NOMENCLATURE OF THE OHIO FORMATIONS 537 



the Huron shale is shown in the gorge of this river, which was 

 supposed to afford excellent exposures of this shale, while to the 

 west of the Huron River the streams have not cut deep gorges 

 and the older rocks are poorly shown. It is evident that further 

 field work in northern Ohio is necessary before a satisfactory 

 name and classification can be proposed for these shales ; there- 

 fore, for the present, the name "Huron shale" is retained. 



The present year Professor T. C. Hopkins has applied the 

 name "Huron limestone" to a formation in Indiana.' 



17. The local names of "Sandusky" and "Columbus lime- 

 stones"are used for the Devonian limestones instead of Onondaga 

 (Corniferous) of the New York classification, because it is prob- 

 able that the Sandusky limestone ought to be correlated with 

 rocks of later age than the Onondaga limestone, viz., the lower 

 part of the Erian series of New York. Confirmation of this idea 

 is found in a paper by the late Edward Claypole which has just 

 teen published.^ 



" Sandusky " is used instead of " Delaware limestone " because 

 both names evidently refer to the same formation, and "Sandusky" 

 antedated "Delaware limestone" by five years. Dr. Newberry 

 published the name "Sandusky limestone" in 1873, and stated 

 that it " is the rock quarried at Sandusky and Delaware," 3 and 

 the " Delaware limestone " was apparently named by Dr. Orton 

 in 1878 on account of "its occurrence at Delaware, and the 

 extensive use made of it at that point," "♦ 



18. Mather in 1859 in a "Concise Geological Section of 

 the Rocks Perforated by the State House Artesian Well, at 

 Columbus," used the name "Columbus limestone" for No. 3 of 

 the section which was given as 138^ feet in thickness, the top 

 of which was 138 feet below the surface and covered by 15 feet 

 of "slate" above which was 123 feet of drift, s The slate and 

 Columbus limestone are again mentioned on p. 11, where he 

 stated that they "approach in character, and may be equivalents 



^ Bull. Geol. Soc. Amer., Vol. XIII (February, 1 903), p. 519. 



^Ai7i. Geol., Vol. XXXII (July, 1903) p. 35. 



^Rept. Geol. Surv. Ohio, Vol. I, Part I, p. 143. * Ibid., Vol. Ill, p. 606. 



5 Report on the State House Artesian Well at Columbus, Ohio, p. 6. 



