212 The American Geologist. October, 1902. 
so much from the standpoint of the Cincinnati series as from 
the Clinton. The beds are not clearly delimited from the beds 
below, though these latter Foerste frequently refers to as "the 
richly fossiliferous shales underlying the Madison bed." 
In Ohio several feet of strata immediately below the Clinton 
are rather different from the strata below them. To these 
Foerste gave the name Belfast Bed, from the town of Belfast, 
in Highland county, considering them the strata which had pre- 
viously been correlated by Orton with the New York Medina. 
As these strata were traced northward and westward, they were 
found to change their lithological character. Later Foerste 
thought the clay underlying the Belfast Bed was Orton's Me- 
dina. This Belfast Bed the writer would include in the Madi- 
son. It is immediately overlain by the Clinton, so that the 
Medina formation is lacking in the Cincinnati area. 
As shown by the quotations from Foerste's Indiana Report 
the Madison formation at Madison, Indiana, consists mainly 
of a massive, heavy-bedded, sandy-appearing limestone, the 
layers usually of various shades of brown. As the formation 
is traced to the north, the limestone is seen to gradually give 
place to shale. At Versailles, Indiana, it contains both lime- 
stone and shale, the former in excess as shown by several ex- 
posures. On Elkhorn creek, four and one-half miles south of 
Richmond, there are good exposures of these beds. Here the 
greenish and bluish clays predominate over the limestone. By 
the time Dayton, Ohio, is reached, the limestone has almost dis- 
appeared and the formation consists almost entirely of blue clay 
and clayey shale. It preserves this character on the east side of 
the uplift, but on account of its soft nature and the topographical 
conditions of the country it is seldom exposed. A few feet are 
exposed in a small branch of Dutch creek in Clinton county. 
There are also occasional other small outcrops in this county. 
The writer has seen no outcrop on the east side where the en- 
tire thickness was shown so as to permit measurement. The 
thickness on the east side appears to be about 30 to 40 feet, on 
the west side from 40 to 60 feet. 
The Madison division closes the Ordovician. It extends 
upward to the base of the Clinton, the first formation in the Cin- 
cinnati area of (Upper) Silurian age. No unconformity be- 
tween the two, either by erosion or by position has been de- 
