922 GEOLOGY OF OHIO. 
E. CONNECTIONS BETWEEN THE SEVERAL PORTIONS OF THE FIELD. 
The foregoing statements ag to the stratigraphical order of the rocks of 
the Ilanging Rock District embraces the main result already reached. 
The results have been stated as facts, and no proofs of the correctness of 
the interp’etations by which they have been reached have been given, 
except incidentilly. Inasmuch asa new place is here assigned to the 
two most important horizons of the district, viz , to Coal No. VI and to the 
Gray or Hanging Rock Limestone, with the ore that covers it, the 
grounds on which these changes are made will properly be demanded. 
A brief statemeat of the facts which establish the order here claimed, 
will, therefore, now be given. 
The Gray, or Hanging Rock Limestone, (Ferriferous of Andrews) 
which constitutes, by far, the best known stratum of the district now 
under review, wus followed by Prof. Andrews as far north as Elk 
and Madison townships, Vinton county. The Nelsonville seam (Coal 
No. VI) was traced southward by him to the same townships. No exact 
connection was established between these two important horizons, but 
the conclusion was announced that the Nelsonville coal found its place 
immediately below the Gray Limestone, constituting the Limestone Coal, 
or No IVa, of our present series, and that “an entire change in the 
deposits” began here and continued throughout the whole range of the 
Nelsonville coal, (pages 61, 72, 115,) Report of Progress, 1870) <A mis- 
take in the identification of the Blue or Zoar Limestone, with the 
Putnam Hill Limestone, which prevailed in the work of the district for 
the first two years of the survey, but which was corrected by Prok 
Andrews in Vol. I. of the Final Report, increased the confusion. 
The correctness of Prof. Andrews’s view was publicly called in question 
by Andrew Roy, E-q., State Mine Inspector, in his Third Annual 
Report, (report for 1876, page 153) Mr. Roy asserts the true place of the 
Gray (Ferriferous) Limestone to be between Coals No. 1V and No. V, and 
frequently directly over Coal No. V, instead of over Coal No. VI. He also 
declares this limestone to be the equivalent of the Putnam Hill Lime- 
stone. | 
On page 157 he also makes the New Castle Coal, of Lawrence county, 
Coal No. V, and the Sheridan Cual, Coal No. VI, instead of No. VII, as it 
had been previously counted. Hither of these changes would go far 
toward carrying the other with it. . 
The result of the examination here recorded shows that Mr. Roy was 
entirely rizht as to the last point and substantially right as to the first. 
For the purpose of determining the true order through this unsettled 
portion of the field, a line was selected which connected the Nelsonville 
