The Geology of Cincinnati. 53 
from “‘ Keys’s Hill” across the Ohio River to ‘“‘ Botany Hill” 
in Kentucky. It isinteresting to note that the main divisions 
of the Cincinnati strata are well indicated. The Blue Lime- 
stone was considered to have a thickness of at least 1,coo feet. 
The general arrangement of the strata of Ohio was fairly 
well understood, and the Cincinnati uplift as the axis upon 
whose slopes later formations were successively laid down was 
well made out. 
As early as 1829 the Blue Limestone was correlated by 
Lardner Vanuxem* with the rocks occurring at Trenton 
Falls, New York, from their fossil contents. This determina- 
tion was generally accepted for many years. 
In the following decade the magnificent work of the New 
York Geological Survey, by making known and naming the 
successive Paleozoic formations of the State of New York, 
laid the groundwork for American geological science. Two 
questions the survey left unsettled; one produced the cele- 
brated Taconic controversy, the other was the real meaning 
and scope of the term Hudson River group. Dr. W. W. 
Mather,{ in charge of the First Geological District, proposed 
the name Hudson River slate group, which he afterward{ 
amended to Hudson River group, for the lowest rocks in his 
district, exposed along the Hudson River. The rocks were 
generally unfossiliferous, and more or less altered after their 
deposition. The term, while accepted by the Geological 
Board of the State, seems not to have received entire approval 
or been clearly understood. Emmons§ continued to use the 
term Lorraine Shales for a formation, finely shown in the 
gorges of Jefferson County, New York, occupying supposedly 
the same geological horizon. 
Gradually doubt arose as to Vanuxem’s correlation of the 
Blue Limestone with the Trenton of New York. Prof. 
James Hall,|| in 1842, considered a green shale occurring at 
Newport, Kentucky, equivalent to the Utica shale of New 
York, and the rock below it, seen only during low water in 
* Amer. Jour. Sci., XVI, 1829, p. 256. 
+ Fourth Ann. Rep. Geol. Survey New York, 1840, p. 212. 
{ Geol. New York, Geol. First Geol. District, 1843, p. 367. 
2 Geol. New York, Part II, Second Geol. District, 1842, p. 119. 
| Amer. Jour. Sci., XLII, 1842, p. 61. 
