y GEOLOGY OF OHIO. 
Holmes county, Coal No. 4 shows variations similar to those already de- 
scribed. Asa whole, it exhibits-a strong tendency to pass into cannel, 
and in Bedford and Jefferson townships, Coshocton county, it becomes an 
excellent cannel coal, from three to six feet in thickness. Near Flint 
Ridge, in Licking county, it exhibits the same character. It is plain, 
from the foregoing facts, that while Coal No. 4 is capable of assuming 
considerable local importance, and of adding much to the value of a single 
farm, it cannot be estimated as an important element in the resources of 
Tuscarawas county. 
LIMESTONES AND CLAYS. 
LTimestones.—In the tables at the end of this chapter will be found 
analyses of specimens of the limestones which overlie Coals No. 3 and 4. 
These are, however, very variable in composition, and chemical analyses, 
unless in great number, would fail to indieate their economic value. 
Over the greater part of the county both limestones are fairly pure, and 
exhibit the normal character of similar strata elsewhere, interstratified 
with the other Coal Measure rocks. From the quantity of earthy matter 
and iron which they always contain, they produce a brown lime when 
burned. This is unfit for the finishing coat of plastered walls, but it 
makes a good and strong mortar, for which purpose it is largely used, the 
white limes of the lake region supplying the material for surface and 
finer work. The lime produced by the Putnam Hill and Zoar limestone 
is as valuable as any other for fertilizing, but it generally happens that 
in the region where this is most readily obtainable the soil is already 
well supplied with calcareous matter, and naturally fertilized from the 
decomposition of the limestone strata in place. Lands that are deficient 
in this important ingredient will derive as much benefit from a dressing 
with the brown lime as any other. | 
An important use of the limestone of both the strata which have been 
mentioned is for furnace flux, a purpose which it serves well, where the 
purer varieties are used. 
Both limestones are prone to run into chert, and in some places con- 
sist largely of flinty matter. These are of course unfit to be used for 
either lime or flux, but they serve an excellent purpose for road-making, 
supplying, indeed, the very best material for macadamized turnpikes. 
The question of the origin of the silica which so frequently impreg- 
nates, and sometimes replaces the lime of the Coal Measure limestones, 
will be found discussed in the chapter on the Carboniferous system, which 
forms the introduction to the geological portion of Vol. II.; and reasons 
are there given for supposing it to be derived from minute plants (dia- 
