Cincinnati Society of Natural History. 



undoubted Niagara of this state. The occurence of Halysites in the 

 eastern portion of the argillaceous sandy bed might belong to the same 

 order of events This bed, formerly identified as the Medina, has 

 been designated in the preceeding pages as the Belfast bed, from its 

 most typical region of development in Highland County in Ohio. 



Between the Clinton or Montgomery bed and the " Niagara 

 shales" is found everywhere in Ohio a firm white or bluish pure lime- 

 stone, sometimes somewhat argillaceous, or magnesian, which evi- 

 dently merges in some cases into the " Niagara shales" above, and 

 which in all cases is readily distinguishable from the Clinton below. 

 Its fossils are not of the Ohio Clinton type but evidently herald a new 

 horizon. Many species are identical with the Niagara as identified in 

 Indiana, at Waldron and at other localities. This is called the 

 Dayton stone in Ohio. 



Omitting therefore all reference to the Lower Helderberg lime- 

 stone, the Hillsborough sandstone, and the Guelph, as a formation 

 separate from the Cedarville bed, we have in Ohio the following series 

 for the lower part of the Upper Silurian : 



t-. . . . f Cedarville bed, 



Dolomitic stone, < c • a , , , , 



' t Springfield bed, 



More argillaceous stone, ^ Niagara shales, \ Niagara. 



White pure limestone, | Dayton stone, 



•j-v. , , ,. f Clinton rock or Mont- i More Niagara than 



Pink or red pure limestone, \ gQmery bed> [ CHnton> p * rhaps 



More sandy and argilla- f Bdfast bed j Lower Silurian, 



ceous stone. ( j 



In the southeastern part of Indiana the corresponding rocks are 

 as follows: 



More argillaceous material, ] The Waldron shales, 



1 



White or bluish pure lime- f The Laurd bed " Niagara, 

 stones, with intercalations < (Osgood Phase.) 

 of chert in the upper hall, f & 



White, red, or brown pure f ^ 



limestone, or in one lim- ! The Clinton rock or | More of Niagara than 



ited region a hard blue 1 Montgomery bed, { Clinton type, perhaps. 



sandy rock, [ 



ery argillaceous rock, i 

 clay, or, sometimes, mod 

 ately hard, clayey shale, 



Very argillaceous rock, a C extension of I «■ mi n Han 



clay, or, sometimes, mod- \ the Bdfast bed> > Lower Silurian. 



