668 GEOLOGY OF OHIO. 
individual members outrank in importance the last formation treated. 
A tabular view of these subdivisions is here appended : 
SUBDIVISIONS OF THE NIAGARA GROUP. 
Feet. 
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BHT Wiest (Union "beds ig keyed aca Cal Sec acon a cites e saletaut cies hice annem nanan 10 
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A WX os 20 Beanie pre a no Seen nia Hr naa Ne AA RAB aie ot lo \ lat Heino 125 
The separate elements will be briefly noticed. 
(a.) The Dayton limestone, which forms, wherever it occurs, the very 
base of the Niagara system, is an exceptional formation. It occupies 
isolated areas through three or four counties of the Third Geological Dis- 
trict. Its place in the series throughout the district generally and the 
country at large is occupied with widely different kinds of deposits. 
The typical locality, as the name of the formatign denotes, is Dayton, 
Montgomery county. For a detailed description of the formation, the 
reader is referred to the Report of the Survey for 1869. 
The Dayton stone is found in great excellence and in considerable 
quantity in Greene county. Beginning on the western border, we find 
it capping the outlier of cliff Limestone that lies south-west of Harbine’s 
Station, in Beaver Creek, township. Owing, however, to the greater ac- 
cessibility of contiguous deposits—especially those of the Dayton dis- 
trict—these beds have been but little developed. Neighborhood supplies 
have been drawn for a long time from the farms of Moses Shoup, Archi- 
bald Huston, and others; but within the last two or three years larger 
quantities have been taken out and distributed from Harbine’s Station, 
by the Dayton and Xenia Railroad. The stone, as here found, has all the ° 
characteristic excellence of the formation in thickness, homogeneity, du- 
_ rability, and color; but its value is somewhat reduced by the abundant 
crystals of sulphide of iron (known by the quarrymen as sulphur), which 
weather on exposure, and disfigure the surface by dark-brown stains. 
The area underlain is considerable, and every foot of the deposit is sure to 
come into demand with the increasing age and resources of the surround- 
ing country. | 
The next outcrop of it is found on the farm of Mr. James Collins, 
Xenia township; but though the stone is unmistakable here in its gen- 
eral character, it is much reduced in thickness and, consequently, in 
value, and evidently marks the limit of the deposit in this direction. A 
