CORRELATION OF STRATA. cil 
Above these there are numerous layers of crystalline limestone, three to ten inches in thiclx- 
ness, separated by relatively thin bands of shale. In the upper 60 or 70 feet the bedding 
is more irregular and the limestone layers thinner and generally argillaceous, unfitting 
them for building purposes. Fossils are well preserved and exceedingly plentiful, and 
among them may be recognized nearly ever species that has been described from the 
equivalent beds in New York. Perhaps 300 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. es 
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.* Hast and southeast of Oxford in Ohio, the whole group consists 
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 fossiliferous, 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, Tetradium, 
Labechia and Beatricea. 
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 also 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 Labechia ohioensis Nicholson, which is scarcely 
distinct from the Trenton Stromatopora pustulosa of Stafford; Streptelasma rustica Billings, 
which is very similar to S. corniculum of the Trenton; Orthis subquadrata Hall, Leperditia 
cecigena Miller, Isochilina subnodosa Ulrich and Columnaria alveolata Goldfuss are also 
* Prof, Orton’s name ‘‘ Lebanon” would have been adopted had his name not been used Rerore for a division of the 
Trenton period by Prof. Safford. The Richmond exposures besides are larger and more characteristic of the group than 
those near Lebanon, Ohio. 
