UNCONFORMITY AT BASE OF ONONDAGA LIMESTONE 313 
is not continuous and has not been proven to be Oriskany, it has been customary 
of later years, and perhaps wisely, to drop the Oriskany sandstone from the 
Ohio scale and include these deposits with the Columbus limestone to which 
they are at least very closely related. 
It will be noted in the description of this disconformity in 
Ohio that it is characterized locally, as in central New York, by 
a conglomerate. This is particularly well developed in the central 
Ohio region near Columbus, where according to Dr. Stauffer’ 
decided evidence of the erosion period which intervened is found 
in the well-developed basal conglomerate of the overlying Columbus 
limestone. 
INDIANA 
Ohio valley.—The Columbus limestone of central Ohio and the 
Onondaga of New York are represented in southern Indiana by a 
limestone which bears the closest resemblance to them faunally. 
This formation has been named in Indiana the Jeffersonville lime- 
stone. It is the lowest formation of the Devonian as developed 
at the Falls of the Ohio. This formation has been shown to hold 
the same fauna and to be the equivalent in the Ohio valley of the 
Onondaga limestone of New York.? It lies between the Sellers- 
burg limestone and the Louisville limestone of Silurian (Niagaran) 
age. This formation has perhaps its most typical development 
at the Falls of the Ohio just below the city of Jeffersonville, where 
it has a thickness of about 20 ft. It is a light- or bluish-gray 
crystalline or subcrystalline limestone, occurring both as a massive 
and asa thinly stratified limestone. 
The fossil coral reef for which the Falls of the Ohio have long 
been noted occurs in the lower part of this formation. The im- 
portant rdle played by corals in the formation of this limestone 
is indicated by the great size attained by some individuals. One 
Favosite (F. hemisphericus ?) which was measured has a breadth of 
5 ft. and a height of slightly more than 2 ft. Spirifer acuminatus 
t“The Devonian Section of Ten Mile Creek, Lucas County,” Ohio Nat., VIII 
(19908), 273. 
2K. M. Kindle. The Devonian and Lower Carboniferous Faunas of Southern 
Indiana and Central Kentucky, Bull. Amer. Pal., No. 12 (1899); The Devonian 
Fossils and Stratigraphy of Indiana; Ind. Dept. Geol. Nat. Res., 25th Ann. Rept, pp. 
220-763, 31 pls., Igor. 
