CORRELATION OF STRATA. < ni 



Above these there are numerous layers of crystalline limestone, three to ten inches in thick 

 ness, separated by relatively thin bands of shale. In the upper 00 or 70 feet the bedding 

 is more irregular and the limestone layers thinner and generally argillaceous, unfitting 

 for building purposes. Fossils are well preserved and exceedingly plentiful, and 

 them may be recognized nearly ever species that has been described from the 

 equivalent beds in New York. Perhaps 800 species of fossils are known from the Cincinnati 

 exposure of the Lorraine group and of these at least two-thirds are limited to the group, 

 which is, considering the very similar lithological characters of the preceding and 

 succeeding beds, a surprisingly large percentage. 



Resting on the Lorraine there is a series of alternating thin bedded shales and lime- 

 stones and in some localities finally a sandstone, in all quite 350 feet thick in southwestern 

 Ohio and southeastern Indiana. Almost the entire series is excellently exposed at Rich- 

 mond. Indiana, so that the name Richmond group which we propose to apply to the series 

 is eminently appropriate.* East and southeast of Oxford in Ohio, the whole group consist* 

 of thin bedded limestones and shales, but at Richmond the upper part shows an increase 

 of arenaceous matter while the uppermost layers of shale have become harder and include 

 one or two heavy beds of impure limestone. Southward from this locality in Ripley and 

 Jefferson counties (Indiana) the heavy layers are increased. In the last county their 

 texture is very compact and the color a drab or dove reminding one in both respects very 

 greatly of some beds of the Trenton period. In Indiana and Ohio this upper part of the 

 group is. as a rule, not very fossil iforous, but when the bed is traced over into Kentucky it 

 becomes a veritable coral reef reaching from Jefferson county (Ky.) to and beyond Marion 

 county. The rock in this distance has changed some, being in the last county of a yellowish 

 color and finely arenaceous texture, the whole giving way very readily under the weather 

 so that the surface is sometimes thickly strewn with masses of Columnaria, Tctradiiim. 

 Labcchia and Beafricea. 



Near the southern border of Kentucky, at Burksville, this upper member is a true 

 sandstone which Prof. Shaler has called the Cumberland sandstone. But it assumes very 

 nearly that character locally aleo near the Ohio river, as in Oldham county where over 30 

 feet of it consists of greenish arenaceous shales and fine grained thin bedded sandstones. 

 Linney was probably correct in correlating this bed with the Oswego sandstone of 

 New York. 



An interesting paleontological fact is the recurrence in the Richmond group, either as 

 identical or closely related forms, of numerous species that, while they are all wanting in 

 the Utica and Lorraine groups, are common fossils of one or the other of the groups of the 

 Trenton period. Of these we may mention Labechin ohioensi* Nicholson, which is scarcely 

 distinct from the Trenton Stromatopora putMosn of Stafford; StrepleUuma ruatica Billings, 

 which is very similar to S. corniculum of the Trenton; Orfhis subquadrala Hall. Leper<lilia 

 catcigena Miller, Isochtlinu tubnodota Ulrich and Columnarin tih-<-ol<it<i Goldfuss are also 



Prof Ortoo'i BUM Lebanon " would litre bci adopted had bit nao.* Dot (MM UMd befor* for a dUUloa of U> 

 Trrnloo period bjr Prof, Hafford. Tb* Richmond expoaar** braid** ar* larger and nor* caaneMrtoUe of ib* croup ibaa 

 Urn** near Lebaoo*. Ohio. 



