32 GEOLOGY OF OHIO. 



There are a few sections in which the Cuyahoga shale is more largely- 

 replaced by these freestone layers than in the general account above 

 given. In the cuts of the Marietta and Cincinnati Railroad, east from 

 Chillicothe, the freestone appears to constitute a notable proportion, per- 

 haps fifteen or twenty per cent, of the whole material. There are other 

 points at which the stone has no value. 



Under cover the Cuyahoga shale retains with great distinctness and 

 persistency the same characteristics that are found in its outcrops. From 

 the deep drillings of eastern Ohio, wherever its horizon has been reached, 

 there are uniformly reported three hundred or four hundred feet of white 

 shales with occasional sandstone layers through which the drill descends 

 rapidly and easily. The Buena Vista courses are also frequently reported 

 directly above or at least near to the Berea shale. 



The fossils with which the Cuyahoga shale has b en credited have 

 been largely derived from the division next to be described, while this was 

 counted a part of the shale. As here limited, it is, for the most part, poor 

 in fossils. The surface of many of its beds are marked with the impres- 

 sions of the cock-tail fucoid, and in its upper portions occasional courses 

 are found in which the animal fossils of this age are abundant and well 

 preserved. The most characteristic and interesting fossils of the Cuya- 

 hoga shale, proper, are preserved in concretions, as has recently been 

 shown by Professor Herrick. 



He. The Logan Group. 



The divisions of the Waverly series in northern Ohio as 

 laid down by Newberry, happened to be made at a point 

 where the section is abnormal and incomplete. By atrophy or 

 by overlap, the upper member of the series is wanting in the Cuyahoga 

 Valley, or is at least very inadequately represented there. The 

 missing member is, in volume, second only to the Cuyahoga shale, among 

 the divisions of the Waverly. It is much richer in the fossils of the Sub- 

 carboniferous than any of the other members. In composition it is varied 

 and striking, one of its elements being a massive conglomerate, or series 

 of conglomerates, not less than two hundred feet in its largest sections, 

 which extends in unbroken outcrop through at least a half dozen counties 

 of Ohio. No good reason can be found for dividing the Waverly series at 

 all, if a member like this is to be left without a name, or is to be merged 

 with an unlike and incongruous division from which it is as sharply differ- 

 entiated as any one stratum ot Ohio is from any other. 



A typical or representative section of this group is scarcely possible, 

 but the most characteristic and persistent part of the series is one of the 

 conglomerates that occurs near the bottom. At all events, coarse rock, 

 if not always technically conglomeritic, is generally found here. Pebbles 

 do not in all cases make a conspicuous part of the rock when it takes a 

 conglomeritic phase. The most characteristic feature of the pebbles in 



