132 GEOLOGY OF OHIO. 



Coal No. 1. 



This is probably Coal A of the Pennsylvania geologists, and is popularly 

 known in north-western Pennsylvania, where it is largely mined, as 

 the Sharon, or Ormsy coal. It is there sometimes covered with heavy 

 patches of Conglomerate, and has been regarded as a sub-Conglomerate 

 coal, but, as I have shown elsewhere, its true position is above the Con- 

 glomerate. In Ohio it is the lowest seam in the series, usually from 

 twenty to fifty feet above the Conglomerate. It is best known here as the 

 "Briar Hill," "Mahoning Valley," or "Massillon" coal. In Jackson county 

 it is largely mined, and in the southern part of the State is known as the 

 "Jackson coal." This has heretofore been regarded as the most valuable 

 coal seam in the State, from the fact that in many localities it is of good 

 thickness, of remarkable purity, and well adapted in the raw state to 

 the smelting of iron ores. It is, indeed, a typical furnace coal, and forms 

 the fuel by which fully one-half the iron produced in the State is manu- 

 factured. Proof of its purity is furnished by the fact that a large amount 

 of iron is made with it which is used for the manufacture of Bessemer 

 steel, car wheels, etc. Unfortunately, this is an exceedingly irregular 

 seam. This peculiarity is due to two causes, which have been already 

 referred to, viz., it was the first accumulation of carbonaceous matter in 

 the great peat bog that subsequently became our coal basin ; as a con- 

 sequence, it occupies only the lower portions of the irregular bottom of 

 the basin, and was never deposited over the ridges and hummocks which 

 fringed the margin, or, as islands, dotted the surface of the old coal marsh. 

 The second cause of its absence is that it was extensively cut away by 

 currents of water in rapid motion which swept over the coal marsh in a 

 submergence that followed its formation. The channels excavated by 

 these currents were generally filled with sand, and this now converted 

 into sandstone forms the "horsebacks" which cut out the coal. They are 

 connected with the great stratum of sandstone which I have called the 

 Massillon sandstone, and which is generally separated from the coal by 

 a bed of shale ten to forty feet in thickness. Coal No. 1 has its best 

 development in the Mahoning Valley. It is here very compact, working 

 in large blocks, from which fact it has received the name of Block coal, 

 and is remarkably pure, as is shown by the series of analyses given 

 below. 



In Geauga county the Briar Hill coal reaches as far north as Burton, 

 but only in a narrow strip and detached islands, and is there of little 

 value. 



In Portage county it is mined at Palmyra, but its line of outcrop is here 

 concealed by heavy beds of Drift, and what its development is has not yet 

 been determined. It has been struck in borings made in the valleys of 



