290 GEOLOGY OF OHIO. 



The blue color, close, crystalline texture, frequent argillaceous depos- 

 its, and regularity of beds?, as well as the occurrence of Hamilton fossils 

 through the whole of the Upper Corniferous, as described in the reports 

 on the counties of Sandusky and Seneca, and more especially of Pauld- 

 ing and Defiance, are indications that the Hamilton characters pertain- 

 ing to the formation are confined to the upper thirty-five feet. These 

 characters are very well displayed in the quarries at Delaware, Marion, 

 and Sandusky, while the characters of the Lower Corniferous, as the 

 .term has been used by the writer, are seen at the quarries at Delhi, in 

 Delaware county, and at Marblehead, north of Sandusky Bay. It is also 

 well exposed in the creek bluffs at Bellepoint, in Delaware county, al- 

 though at that place the beds exposed lie below the Delhi beds. 



The upper surface of these beds can be seen on the Olentangy, near 

 Norton, pn the land of J. B. Wyatt, Mary Wyatt, and of John Brundage, 

 where they have been opened for building stone. They are also quarried 

 near Waldo, in Marion county, in a similar situation, in the bed of the 

 Olentangy. The only other undoubted exposure of the very highest 

 beds belonging to this formation that is known occurs near Delaware, 

 likewise in the bed of the Olentangy. It is mentioned in the section of 



is supposed by Prof. Winchell to be the rock specifically referred to as the probable 

 equivalent of the Hamilton. In this he is in error, as the bed referred to as a possi- 

 ble representative of the Hamilton in Delaware county is one described by Mr. Hert- 

 zer as a light-blue marly stratum, containing concretions with fish remains different 

 from those of the overlying Huron. It would seem from Prof. Winchell's report that 

 he has not encountered this deposit. His Olentangy shale, without some evidence 

 to the contrary, I should regard, as he does, as merely a subdivision of the Huron 

 shale. 



2d. The Tully limestone ? of Prof. Winchell's sections is certainly Hamilton, as I 

 have obtained from it Tropidoleplis carinatus, Pleriiiea flabella, Nyassa arguta, Spirifera 

 mucronata, etc. That it is the equivalent of the Tully limestone is not indicated by 

 any evidence yet obtained. 



3d. The relations of the limestone called Hamilton by -Prof. "Winchell — the equiv- 

 alent of the '' Sandusky limestone" of our reports — which I have considered a por- 

 tion of the Corniferous group, is discussed in the remarks on the Hamilton group, 

 Vol. I., Part. I., pp. 144-149, and in the report on Erie county, which forms part of 

 this volume. By reference to the passages referred to, I think it will be seen that the 

 weight of evidence is decidedly in favor of its being of Corniferous age. 



The cherty layers which lie between the Huron shale and the quarry-stone at Del- 

 aware are probably Hamilton, but the quarry-stone itself, though containing some 

 fossils which are common to the Hamilton and the Corniferous, has never yielded me 

 any exclusively Hamilton fossils. On the contrary, I have obtained from it quite a 

 number of Corniferous species— such as Spirifera gregaria, S. macra, Strophodonta hemi- 

 spherica, Ptutamerus aratus, which are never known to ascend into the Hamilton. 



J. S. N. 



