THE DELAWARE LIMESTONE 441 



the land was nearer and the land- wash more abundant." 1 The 

 above statements apparently indicate that Dr. Newberry had aban- 

 doned his earlier opinion and now correlated the limestone in San- 

 dusky with the lower division of his Corniferous or the Columbus 

 limestone of central Ohio, instead of the upper division or Delaware 

 limestone. There is, however, no definite explanation of this change 

 of opinion in any of Dr. Newberry's works, as far as the writer is 

 aware, and perhaps the above interpretation of this paper does not 

 correctly represent him in this matter. 



Dr. Charles K. Swartz, of Johns Hopkins University, in the fall of 

 1903 correctly determined the stratigraphic position of the limestones 

 in the city of Sandusky, and correlated them with the Columbus lime- 

 stone of central Ohio. He has thoroughly studied the various expo- 

 sures of the Devonian limestones in Ohio, collected extensively in 

 them, and carefully identified the fossils. Dr. Swartz has written 

 me as follows regarding this subject: 



I find that nearly 87 per cent, of the species reported from the "blue rock" 

 at Columbus and vicinity (including the section from the "smooth rock" to the 

 "bone-bed") occur in that part of the Sandusky limestone in the Lake Erie 

 region which I have referred to the Columbus formation. This includes the more 

 diagnostic forms especially. I think the correlation thus rests on sufficient faunal 

 evidence. Most of these forms do not pass above what I have termed the Colum- 

 bus formation, or are quite rare in the upper division. 2 



In September, 1904, the writer studied the exposures in Sandusky, 

 and fully agrees with Dr. Swartz in correlating all of the limestone, 

 except the very highest layers, in the Hanccck Street quarries with 

 the Columbus formation. It is not improbable that the bone-bed 

 noted in the old quarry on the western side of Hanccck Street repre- 

 sents the well-known one in the Columbus region, which occurs at 

 the top of the Columbus limestone, and at least the dividing line 

 between the Columbus and Delaware limestones occurs not more 

 than from three to six feet higher. 



Since it is proved that nearly all of the reck to which Dr. Newberry 

 gave the name "Sandusky limestone" belongs in the lower instead 

 of the upper division of what he called the "Corniferous limestone," 3 



1 Journal of the Cincinnati Society of Natural History, Vol. XII, pp. 49, 50. 



2 Letter of January 14, 1905. 



3 Report of the Geological Survey of Ohio, Vol. I, Part I (1873), p. 143- 



