418 GEOLOGY OF OHIO. 
At most, there are but three ores in this division. The section meas- 
ures about 100 feet. ! 
3. To the third division, which in its leading elements embraces 
about 150 feet, may be assigned all the ores that are worked at horizons 
higher than the Ferriferous limestone. According to the limits thus 
far followed, the upper boundary of this section should be the Mahoning 
sandstone, but convenience will be subserved in the present instance 
by transcending this limit, and considering here all of the remaining 
ores of the region. This section is mainly composed of kidney ores, of 
which there are two and sometimes three fairly regular horizons, but 
the banded ores of the Upper Freeport horizon must also be included 
with this group. There is not a marked cevelopment of the latter type 
of ores in the Hanging Rock district, but on one furnace tract some 
mining is done, apparently at this level. The Peterson or Red ore of 
Olive Furnace is a stratified ore, and probably of Upper Freeport age. 
It is worked by Olive Furnace. There needs to be added to the list 
one or two higher ores that have been at some time worked in the 
district. The Oak Ridge Furnace was run for the greater part of its 
brief history on an ore that is found 20 feet above the Cambridge lime- 
stone. The Banda ore of Gallia Furnace, and the Hallelujah ore of 
Mt. Vernon Furnace are also examples of this class. These last-named 
ores probably belong to the horizon of the Brush Creek limestone, to 
which the Dugway ore of the Hocking Valley has also been referred. 
The former is not now worked, but the latter is worked to a consider- 
able extent at Mt. Vernon Furnace. 
_In the brief review to be made of the field, the above named divi- 
sions will be followed, beginning with the lowest. 
(1.) ORES FROM THE SUB-CARBONIFEROUS LIMESTONE TO THE 
MERCER GROUP, INCLUSIVE.—LOWEST DIVISION. 
The best single section to represent this series is found on the lands 
of Scioto Furnace, Scioto county. But one addition needs to be made 
to the furnace section, in fact, to represent all the ores of the district, 
from the Upper Mercer limestone downwards. The section, which was 
furnished by Mr. Dudley Hutchins, of Scioto Furnace, and verified by 
our own work, is as follows: 
