308 GEOLOGY OF OHIO. 
A satisfactory measurement of the thickness of the Huron shales could 
not be obtainedin the county ; but from the reported boring for water in 
the machine shops in Norwalk, I estimate it at not less than seven hun- 
dred feet above the top of the nearest exposure of the Cleveland shale. The 
tubing was driven at the machine shops ninety-nine feet through sand 
and clay before striking rock. The well was sunk toa depth of eight hun- 
dred feet from the surface without reaching limestone, and “most of 
the way in black shale.” Near the bottom, a plentiful supply of clear 
sparkling water was obtained, but having an offensive odor. This is 
characteristic of all the water in the county which percolates through 
these shales,and I presume that from the Norwalk well was obtained 
from the bottom of the formation. Deducting one hundred feet for the 
ageregate thickness of the Cleveland and Erie shales, which is certainly 
enough, we have seven hundred and fifteen feet as the thickness of the 
fluron. This is much greater than the reported thickness, but is not too 
great, unless there is an error in the reports of the well-boring. I regret 
that no written record was kept of the drilling. 
Since the field-work of the county was completed, specimens of so- 
called coal found in these shales have been sont me for examination. 
They consist of flat pieces of carbonaceous matter minutely fissured, and 
the fissures filled with thin plates of sulphate of Baryta. The nature 
and origin of these deposits are easily understood. The Huron shale is 
the great oil producing rock of eastern Ohio and western Pennsylvania. 
The slow distribution of the bituminous matter in it has resulted in the 
production of gas and petroleum, which along the outcrop of the strata 
have steadily escaped. The petroleum flowing into a fissure in the rocks 
where it was retained, has parted with its volatile matter, leaving a 
residuum of asphaltum or Albertite which by continued desiccation has 
become minutely cracked and the fissures have been gradually filled 
with barite. Such deposits afford no proof that “the geologists have 
been mistaken,’ and no encouragement whatever to the hope that a 
valuable deposit of coal may be found outside of the ‘‘Coal Measures.” 
True coal in very thin laminez is occasionally found in this shale, and in . 
all the formations between it and the Coal Measures, land plants seem 
to have flourished under favorable conditions during the time of the 
deposit of all the upper Devonian, and the sub-carboniferous rocks. 
It has left its record in plant impressions, and in isoiated thin films 
of coal which may be found on almost any horizon of these rocks; but if 
taken as indications of the presence of workable deposits of coal, they 
will unquestionably lead to disappointment. 
