610 GEOLOGS OP OHIO. 



to ninety-five per cent. It is the nearest approach, to a pure carbonate 

 of lime that is burned, in the large way, in the State. The lime of New 

 Carlisle, Clarke county, has a somewhat higher percentage, but it dees 

 not enter the general market. For all purposes, where a strong and hot 

 lime is desired, this particular layer would meet every requirement. It 

 is called the " smooth rock,'' as has been already stated. This name is we^i 

 applied to it, on account of the planed surface that the upper face of the 

 rock presents. It could very easily be mistaken for a glacial-planed sui- 

 face; indeed, it would seem to have been acted on by some force 

 precisely of this character. Fossils that belong in its substance have 

 been cut down just as they have been worn in the surface beds, by agen- 

 cies of the recent Drift period. No explanation of this unusual phenom- 

 enon is offered. Modern researches indicate that ice periods must have 

 prevailed at wide intervals throughout geological time; but no instance 

 is known to be recorded in which the planing and polishing of ancient 

 glaciers, or icebergs, are preserved in rocks of such high antiquity as 

 this Devonian limestone. 



The smooth rook is overlain by four feet of what is called by the 

 quarrymen, the "Wwe rock". It lies in very thin courses, and is valueless 

 for building stone, and of little worth for lime. 



The course that covers it is the most interesting stratum, not only of 

 the section now under consideration, but of the whole Corniferous forma- 

 tion of Ohio as well. It is one of the most remarkable layers, indeed, in 

 the entire series of American Paleozoic deposits. Reference has already 

 been made to it under the name of the hone bed. The name describes 

 the stratum. It is six inches in thickness, and is literally made up 

 hrough considerable portions of its extent, of the teeth, and plates, and 

 bones of fishes. These remainsare in excellent preservation. The teeth 

 retain the polish and structure of life, but in color they have been uni- 

 formly changed to light brown ; the plates and bones are usually black 

 or brownish black. The surfaces of the plates frequently retain the 

 dermal tubercles, or other ornamentation, with perfect distinctness. The 

 teeth belong mainly to one genus, viz. : Onychodus, and it is not certain 

 that the forms, shown so abundantly at this horizon, differs specifically 

 from those described from other beds. The crest of teeth in the end of 

 the jaw, which is characteristic of this genus, is sometimes, though 

 rarely, found here, the teeth occurring usually detached, but a large num- 

 ber of them being e^itire. Other fossils are found to a limited extent in 

 the bone bed, the most abundant and conspicuous being an Athyris, which 

 closely resembles A. vittata, Hall, from the same general horizon at Louis- 

 ville, Kentucky. 



