A Geological Section at Todd's Fork., 0. — Foerste. 413 
clay eight feet thick, exposed to better advantage farther down 
the stream. Beyond this, its entire coarse lies over the rapidly 
alternating shales and limestones of the Cincinnati group. A 
few hundred feet up stream, on the left bank, is an interesting 
exposure of the overlying rocks. At the stream's edge arises a 
series of layers of a bedded, sandy rock. Its total thickness is 
five feet; a foot from the upper part of the same, a few some- 
what more shaly courses contain a number of annelid teeth. 
The rock is greenish grey in color, turning almost drab on 
weathering. It is referred to the Medina. Above lies a series 
of limestones, eighteen feet thick. The lower part is whitish 
in color, hard, with tendencies towards bedding. This passes 
into a pinkish tinted rock above, without bedding, containing 
rarely a few of the more common favositoid corals. This fea- 
ture is preserved until within six feet of the summit, when the 
rock rapidly assumes a reddish tinge, this becoming more de- 
cided above, and terminating in a reddish brown iron ore, which 
now and then has an oolitic structure. The deposit would be 
valuable for smelting, did it exist in larger quantities. Above 
the pinkish rocks, fossils become very abundant, especially so 
in the iron deposit. This series forms the Clinton group of 
Ohio. Ascending the stream as far as the next bridge, an ex- 
posure will be found on the right bank. The lower eight feet 
are composed of a whitish crystalline stone, with quite regular 
bedding, and unfossiliferous. It is the Dayton limestone. 
Above this are one or two feet of a rock varying towards dolo- 
myte, with a dirty blue color, also unfossiliferous, introducing 
the Niagara shales. The next rock in the series is seen to bet- 
ter advantage at Moody's quarry, one mile east of Wilmington. 
It is a dolomitic, loosely textured rock, very fossiliferous, be- 
longing to the Guelp series. This completes the list of rocks 
traversed by Todd's fork. 
The Cincinnati rocks seen in the creek bed belong to the 
upper, or Lebanon beds. The stratification is very regular and 
approximatelv horizontal. The blue clay layer marks a period 
of disturbance intervening between the deposition of the Upper 
and Lower Silurian periods. It varies greatly in thickness; at 
Fair Haven, near the Indiana line, it is scarcely more than a 
foot thick; at Soldiers' Home, near Dayton, it is perhaps three 
or four feet thick. At the Soldiers' Home exposure a number 
