1S69.] ol [Winchell. 



Let us now inquire whether in Ohio, which lies contiguous to Michigan, 

 anything can be discovered which answers to the Huron group. The 

 lower portion of the series super-imposed upon the Black Slate of Ohio, 

 has generally been passed by with the remark that it appears to be 

 unfossiliferous, or that it may belong to a different epoch from the fos- 

 siliferous sandstones above. I think, however, the thickness of these 

 subter-psanimitic strata has not been generally suspected. As in Michi- 

 gan, so in Ohio, we are indebted to the enterprise stimulated by the late 

 petroleum-industry, for the disclosure of the full extent of the argillaceous 

 and flaggy deposites immediately above the Black Shale. We are now 

 assured of the existence of a vast series of shales in Ohio which corres- 

 pond both in position and in lithological characters to the Huron group 

 of Michigan. In Knox county they attain a measured thickness of 450 

 feet. Here, again, we discover ample scope of strata to answer the 

 demands of the New York Portage and Chemung, without bringing in 

 the Waverly and Gi'itstone series above. 



In Kentucky also, at "Knob-lick," south of Danville, and at other 

 points, we discover a series of argillaceous strata not less than 80 feet 

 thick, reposing upon the Black Shale, and presenting again all the phy- 

 sical characters of the Huron group. As these shales are surmounted by 

 Knobstones of Keokuk age, we have no stratigraphical determination 

 whether they should be synchronized with the Huron group, or the 

 Marshall, or the lower part of the Mississippi group. I think it will be 

 admitted, however, that some presumption exists that they lie in the 

 horizon of the Huron Shales. 



In lov/a it seems not unlikely that the base of the yellow sandstone 

 series, with its bluish, slightly micaceous sandstones, comes into the 

 same zone ; while the blue sliales, 80 feet thick, beneath the Lithographic 

 limestone in some parts of Missouri, may probably be more correctly syn- 

 chronized with the argillaceous shales of the Huron group than with the 

 black or Genesee section of that group. I would suggest also that the 

 Illinois shales, somewhat doubtfully referred by Prof. Worthen to the hori- 

 zon of the Genesee shale, may lie rather in the horizon of the Huron 

 shales of Michigan. 



It appears from the foregoing statements that we are by no means com- 

 pelled to resort to the Waverly and Marshall series to discover the western 

 representatives of the Portage and Chemung of New York. If the appar- 

 ent continuity of the eastern and western formations should appear to 

 compel such identification, let it be remembered that the Knobstones 

 stand in the same apparent relation to the Waverly that the Waverly does 

 to the Chemung, and yet we yield to the weight of paleontological evidence 

 in denying their equivalency. If, moreover, it appears that the Chemung 

 and Portage have become finer and more argillaceous in their westward 

 extension, it will be remembered that the Waverly strata also, when traced 

 into Indiana, Illinois, and Missouri, have assumed a finer constitution, 

 and have received moreover that accession of calcareous constituents 

 which we always expect to characterize formations remoter from the 



A. P. S. — VOL. XI — K 



