GEOLOGY OF EASTERN OHIO. 595 



are capped by beds which are so flat, that in the direction of the dip it may be ten or 

 fifteen miles before the strata disappear beneath the valleys. 



On a general map, the outline of the formations may be represented by a line drawn 

 from one outlier to another ; or it may be drawn midway between the outliers and the 

 points where the strata sink to water level, as I have attempted to do in the present case. 

 The true outline is very sinuous, with sharp projections and indentations, which can be cor- 

 rectly laid down only after tedious explorations, on plans of a large scale. 



In that part of the coal region of Ohio west of the Muskingum and north of the Ohio 

 Eiver, Messrs. ,Briggs, Hildreth, and Foster traced out some prominent beds of the coal 

 series, which they regard as continuous. 



First, the Buhr stone. — From the line between Gallia and Jackson counties, in the town- 

 ship of Greenfield, it was followed northerly to the line between Athens and Vinton coun- 

 ties, in Waterloo ; and thence, through Hocking and Perry a few miles east of Somerset, 

 to the hills overlooking the Licking or Pataskala River, at the Falls, in Muskingum County. 

 a distance of eighty-five miles. 



Second, the Lower Limestone Group. — Dr. Hildreth traced a bed of fossiliferous lime rock, 

 from a point six miles west of Gallipolis, northerly a little to the east of Athens, crossing 

 the Muskingum River just above McConnelsville, from whence it bore more easterly, to 

 the National Road, near Cambridge, in Guernsey County. 



Several hundred feet above this is the great Pomeroy coal seam, which was recognized 

 through the counties of Meig's and Athens, and the western part of Washington, to the 

 Muskingum River, thinning out in that direction. 



Third, the Upper Lime Group. — Several hundred feet above the Pomeroy seam is another 

 marked limestone group, which appears on the Ohio at Letart's bend, and extends thence 

 northeasterly, in a curved line parallel with the general course of the river, to the Mus- 

 kingum, six or eight miles above Marietta. The profile from Cleveland to Wheeling, which 

 accompanies this paper, shows the position of the great Pittsburg coal seam, on the upper 

 Ohio. Messrs. Rogers of the Pennsylvania survey, and Briggs of that of Virginia, traced 

 this bed along its outcrop on the Monongahela at Brownsville, down the valley to Pitts- 

 burg, where it rises to the tops of the hills; and thence across the Pan Handle to Steuben- 

 ville. It does not, as I am aware, cross to the northwest side of the Ohio, above Steuben- 

 ville, where on the Virginia side it is high in the hills. It dips southerly along the Ohio, at 

 a rate which brings it down to high-water level at Wheeling. Above the Pittsburg seam, 

 at a short distance, is a heavy bed of lime rock, or rather a group of calcareous strata, 40 

 to 60 feet in thickness. Below this coal seam is a no less marked bed of sand rock, 300 to 

 400 feet in thickness, which produces no workable coal, and is therefore called in Pennsyl- 

 vania and Virginia, " the barren sandstone " group, or the lower sand rock. As yet neither 

 the Pittsburg seam nor the upper lime group have been identified on the Muskingum. 



Professor E. B. Andrews, of Marietta, after much local examination in that quarter, 

 finds a north and south line of disturbance near the valley of Duck Creek, a few miles east 

 of the Muskingum. This disturbed country, extending from Noble County, across the river 

 Ohio, to the " Burning Spring," on the waters of Little Kanhawa, is the seat of petroleum 

 springs and wells. 



It is therefore not settled whether the upper lirne group of Dr. Hildreth corresponds 

 to that above the Pittsburg seam at Wheeling. It is scarcely supposable, that so heavy 



