24 Cincinnati Society of Natural History. 



fossils. The upper is 8 to 16 inches thick, and its upper 

 surface is usually well covered with Dalmanella multisecta. 

 A few inches of the shale just beneath the upper stratum 

 is often almost entirely composed of the shells of this brachio- 

 pod. In places, the upper three feet or more of the shale 

 bed is largely limestone, in which case this becomes a prom- 

 inent limestone horizon. The most marked spring horizon 

 of the region is just beneath the lower limestone stratum. 

 Above this stratum, the rocks are porous, allowing the 

 downward passage of ground-water; below, they are quite 

 impervious, necessitating a lateral movement of ground- 

 water. This results in seepage at many places along the 

 outcrop of the upper shale layers, which often is sufficiently 

 concentrated to form permanent springs. The upper lime- 

 stone stratum, which is the highest horizon containing 

 Dalmanella multisecta, is regarded as the top of the Eden. 



3. Fairview and McMillan {Maysville). — Until recently, 

 the rocks of the Fairview and McMillan formations were 

 grouped in one formation, the Maysville, which was sub- 

 divided into five members. In both the Fairview and Mc- 

 Millan, alternation of shale and limestone is the most promi- 

 nent characteristic, more prominent even than in the Eden. 

 The limestone totals about thirty per cent of the thick- 

 ness; and strata six inches thick are common. The shale 

 of the Fairview and McAlillan is often of a lighter blue 

 color than that of the Eden, and much of it is of a coarser 

 texture, and less compact; the limestone, although always 

 impure, is more compact and crystalline here than at any 

 horizon of the Eden. 



Fossils are much more abundant in these formations than 

 in the Eden. The surfaces of many of the layers of crys- 

 talline limestone are almost completely covered with fossils. 

 Throughout these formations, brachiopods and bryozoans 

 are by far the more numerous fossils, while all the other 

 phyla of invertebrates with the possible exception of the 

 Protozoa, are represented. A number of species are per- 



