882 GEOLOGY OF OHIO. 
strikingly shown in the main entry of the present Blue Rock mine. 
The coal is here entirely cut out for many yards. 
Much time and some money have been spent at various points along 
the valley, and especially on the opposite side of the river, in a vain 
search for the Blue Rock coal. The horizon of the coal is everywhere 
made clear, though not generally recognized, by its fire-clay and lime- 
stone, but of the coal itself not a trace may be left. This fact should 
be borne in mind in all investigations directed toward this seam. It 
was never universally distributed, like the Middle Kittanning, in its 
field. ‘So far from being so, it is known to be unusually capricious and 
uncertain. In addition to the irregularity of original formation, the 
seam where once duly formed was afterward exposed to the accidents 
of quite a violent erosion. So coarse a sandstone as the Mahoning can- 
not be explained without calling into action strong currents for its trans- 
portation. From these two causes, viz., failure of uniform and con- 
tinuous formation and waste of the basins that were formed by erosive 
currents, results the exceeding uncertainty of the Upper Freeport coal 
through a large portion of the territory in which it is due. 
The Upper Freeport clay is worked at its proper level at Ballou’s 
Landing, in Brush Creek township. It is here a non-plastie clay of 
good quality. It has been worked to some extent in the fire-brick 
factory at Putnam. ‘The coal does not appear in immediate connection 
with the clay, but it has been found and mined on adjoining farms at 
its proper level. 
THE BrusH CREEK BASIN. 
The least known and least developed, but by far the most promis- 
ing field of the Upper Freeport coal in Muskingum county, is included 
in Clay, Newton, and Brush Creek townships, and jis rendered accessible 
by the valleys of Brush Creek and its tributaries. There is a possible 
important extension of it into Harrison township, as will be presently 
shown. The coal occupies, so far as can be determined by natural 
exposures, parts of Sections 1, Clay; 25 and 36, Newton; 7, 6, 26, 5 
and 27, of Brush Creek townships, but boundaries for a coal field of 
this particular seam, when laid down in advance of careful exploration, 
are of little worth. The probabilities all seem in favor of a large terri- 
tory for this Brush Creek basin. Throughout the area named, it gives 
all the signs of steadiness that can be asked. It is found where it is 
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