DEVONIAN. 315 



Carboniferous is subject to question. It has been customary to draw the Une 

 theoretically and so far as practicable in fact at the top of the Antrim, on paleon- 

 tologic grounds. Lane "''" says : 



In order to get consistent results and thickness one must recognize that the transition to 

 the Berea grit is gradual and a great thickness of Berea grit or strata ascribed thereto is at the 

 expense of the Antrim. * * * 



To put the base of the Carboniferous at the base of the Bedford we should have to split 

 the Antrim in a yery impracticable way, though we could readily enough follow Ulrich's sug- 

 gestion and place it lower. [Lane states that Ulrich would transfer the Antrim to the Carbonif- 

 erous.] It is noteworthy that just as the Sylvania is confined to the east side of the basin along 

 the Cincinnati anticlinal, so is the Berea grit, and when the Berea grit does not appear, then 

 the upper strata of the Antrim have a red facies Hke the Bedford of Ohio, or the Richmond top 

 to the very similar Lorraine. This red facies is, it seems to me, very likely due to exposure to 

 the weather. Where the Berea grit is well developed it is, I believe, never found. It therefore 

 may indicate the uphft generally taken to mark the close of the Devonian and beginning of 

 Carboniferous. 



This is the Michigan phase of the Waverly problem. (See also papers by 



In northern Ohio the Cleveland shale is regarded by Prosser "*"* as the upper- 

 most Devonian, whereas the Bedford shale is placed at the base of the Carboniferous. 

 According to Lane both of these formations are represented in the Antrim shale, 

 and thus, to be consistent with the Ohio scale, the line should be drawn in Michigan 

 in the Antrim itself. This Lane regards as impracticable. 



Following the general usage we discuss the Berea sandstone and overlying 

 formations as Carboniferous. (See pp. 420-421.) 



In 1905 Prosser ®^^ published a classification of the geologic formations of Ohio, 

 which has since been republished with the New York equivalents by Stauffer.'^*^ 

 In another paper ''^° Stauffer describes the Middle Devonian as foUows : 



The Middle Devonian of Ohio naturally falls into three divisions, of which the lowermost 

 is known as the Columbus limestone, the middle as the Delaware limestone, and the upper as 

 the Olentangy shale. This division is based on both lithological and faunal differences which 

 in some respects are more apparent in the vicinity of Columbus, although not wanting in any 

 of the belts of the outcrop. The thickness of each of these three formations varies through a 

 considerable range in different parts of the State. 



The Columbus limestone presents two rather persistent lithological differences which are 

 excellently illustrated in the outcrops along the Scioto River and are not absent even in the 

 northern sections. These two phases of the formation sometimes blend with each other, but 

 occasionally localities are found where the change is abrupt and the characteristics of each 

 portion decided. 



The lower portion of the Columbus limestone consists of a rather porous massive brown 

 limestone, frequently containing a large amount of bitmninous matter and very little chert, 

 but generally having numerous cavities or pockets filled with crystals of calcite. At some 

 places near the base it has been observed to have a pitted or honeycombed structure. It some- 

 times shows a strong oblique jointing and frequently few definite bedding planes. A fresh 

 surface shows a saccharoidal appearance but occasionally glistens with cleavage faces of calcite. 

 There is also a tendency to a banded structure which may be seen in the blocks of most if not aU 

 exposxu-es in central Ohio. This banding, frequently of a wavy appearance, seems to be due 

 to the presence of finely divided bituminous matter. The fossils, except in the extreme up^ner 



