424 GEOLOGY OF OHIO. 
Howard, Pine Grove, Scioto, the Jackson and Wellston Furnaces, all 
take a good deal of it in the course of the year. It is scarcely thicker 
on the average than the lower block. It yields at many points as mel- 
low and excellent ore as any horizon of the series, but it is not reliable, 
and good ore is likely enough to run into a poor or worthless quality 
quite abruptly. It is rougher looking ore than the lower block, as a 
rule. A coal seam comes in occasionally, exactly upon its horizon, as 
will be shown in a subsequent chapter. This makes it probabl+« that 
the ore replaces in part the coal of the Upper Mercer horizon. It is 
decidedly the least valuable of the three block ores. 
The upper block ore has been named by Mr. C. N. Brown, the as- 
sistant who has done most of the work in this field, the Franklin block. 
It was the main reliance of Franklin Furnace during its whole exist- 
ence, and moreover its westernmost outcrops are on the lands of this 
furnace, and it is nowhere better than at this point. Ohio and Pine 
Grove furnaces also put great dependence on this seam. It is known 
in the Ohio Valley as the main block, the others running under and 
thinning out as they go to the eastward, but this one holding its place 
in full force as far as Ashland, Ky. The more common designation for 
it is the Big Red block. By this name it is known at all of the southern 
furnaces where it has its best development. ‘This name suggest one of 
the chief distinctions, and one of the trivial marks of the ore, viz., its 
size, and its color on outcrops. It ranges from 8 to 12 inches in thickness 
on Ohio and Pine Grove lands. At Ironton it measures fully 2 feet, 
but is very close grained and stubborn, and lacking in adaptation for 
use in charcoal furnaces, but Sarah Furnace of Ironton is at present 
using ore from this seam. At Bloom, Scioto and Monroe furnaces, and 
throughout Jackson county, it has a general thickness of 12 or 14 inches. 
The ore seldom fails where it is due, but it is sometimes too coarse and 
rough to secure approval. Good ore, however, comes in from this 
horizon at almost every furnace to which the seam is naturally tributary, 
and at some points the quality is excellent. 
This ore has now been followed under one general name, and with 
quite uniform characteristics from the Ohio Valley to the Vinton 
county line. In Clinton and Elk townships of Vinton county, where 
it is known as the Craig ore, the Robbins ore, and the Huhn block, it 
holds substantially the same features as at the southward, but in Swan 
township it takes on new proportions, and has been found within the 
