FOSSILS OF THE CLINTON GROUP. 



517 



At Todd's Fork near Wilmington this sandstone is about five feet thick, 

 and contains in its lower layers a number of annelid teeth, some of which 

 were described in the American Geologist: Notes on a Geological Sec- 

 tion at Todd's Fork, Ohio, 1888, p. 412-419. Figs. 1-7, reprinted here. 



Annelid teeth from the Medina at Todd's Fork, Chio. This rock graduates into the basal 

 Clinton so that it is impossible to distinguish the same by a definite plane of separation. Fig. 1. 

 The so-called " skins '' of annelids. Fig. 2. Oenites deripiens, Foerste. Fig. 3. Arabellites procur- 

 sus, Foerste. Fig. 4. Lumbriconereites Austini, Foerste. Fig. 5. Eunicites falcatus, Foerste. 

 Fig 6. Eunicites confinis, Foerste. Fig. 7. Eunicites paululus, Foerste. Figs. 2-7 much magnified. 



So far these are the only localities in southwest Ohio where rocks re- 

 erable to the Medina have been seen by the writer. As a rule the 

 Clinton follows immediately upon the blue clay layer. At one point 

 near Belfast in Highland county, Ohio, a conglomerate occurs in the 

 Clinton, containing limestone pebbles of unknown age in a cement full 

 of Clinton fossils. The pebbles often are nearly two and a half inches in 

 diameter. Strongly indicative of land conditions, nothing comparable 

 with this conglomerate has been found elsewhere in the State and at 

 present no data exist which will determine the source of its pebbles. 

 Owing to the absence of similar phenomena in more western areas of 

 the State, where Clinton exposures are not infrequent, it seems not im- 

 probable that if the pebbles indicate land conditions at some distance not 

 remote from Belfast, this land surface may have lain entirely outside of 

 that area now well known in geology as the area of the Cincinnati anti- 

 clinal. 



The Clinton is generally an unusually pure limestone, containing 

 quite commonly 97.75 per cent, of carbonate of calcium. Its upper 

 courses are ferriferous in some of the more southeastern exposures, the 

 limestone having been replaced in part by a red iron ore. Quite regular 

 deposits extend from Todd's Fork, north of Wilmington, southward. At 

 Todd's Fork the ore occurs in the form of so-called oclitic iron grains, 

 which are evidently pseudomorphs formed b}^ ore replacing little round 



