GEOLOGY OF EASTERN OHIO. 591 



bed of lime rock, the greatest inclination is found to be, south 72° east, 25.2 feet per mile. 

 In the mining region on the Mahoning, around Youngstown, the elevation of most of the 

 entries, and of some of the sumps, has been well taken. Here the bottom seam, commonly 

 called the " Block Coal," frequently rests on the conglomerate, which is thin. From the 

 Mount Nebo works, near Lowell, bottom of the mine 222 feet A, to Briar Hill shaft sump, 

 318 feet A, is, north 46|° east, 7.45 miles; to Ewing's coal, in a drill hole, 305 feet A 

 north 85-£-° west, is 13 miles ; and the result for clip is, south 22|° east, 14 feet per mile. 



A triangle formed by Mount Nebo, Briar Hill, and the coal at Porter's furnace, lyino- be- 

 tween Ewing's and Briar Hill, gives, south 37° east, 13 feet per mile ; and another, connect- 

 ing Mount Nebo, Ewing's, and the sump at Rice, French, & Co.'s shaft, on Mineral Ridge 

 377 feet A, south 18° east, 16.6 feet per mile. In this region, as at Massillon, there are 

 many irregularities in the coal seam, which lies in troughs and basins whose lowest parts 

 are thirty to sixty feet below the outcrop. It requires lines of at least ten miles in length, 

 where the beds are so flat and so much curved, to determine the general direction and 

 amount of their inclination ; but when thus obtained, it will be perceived the results agree 

 very well with each other. 



Elevations in the Lower Coal Seam. 



In Ohio, the coal seams are not persistent, which is shown conclusively by profiles alreadv 

 made, in different parts of the field, extending from the margin to a common centre neai 

 Wheeling. It is therefore a fallacy to suppose that beds in different parts of the basin car. 

 be identified with those in others, either by their associated rocks, or a similarity in the 

 external character of the coal. Where the number of seams in one profile is more or less 

 than in another, there cannot be identity. A bottom seam will of course be everywhere 

 found, from zero to eighty feet above the conglomerate, but it is not everywhere the same 

 seam. It frequently thins out, and disappears, while another seam se'j in, overlapping, or 

 underlapping, as the case may be, having different physical characters and associations, but 

 nearly in the same horizon. Above this, it is very difficult to connect the beds, over large 

 spaces, either of coal, limestone, iron ore, or sandstone. It is very rarely that any bed of 

 the coal series can be traced with certainty one hundred miles. 



Beginning on the State line between Ohio and Pennsylvania, I now give what elevations 

 I have procured for the bottom coal seam, or No. 1, proceeding in order, to the west and 

 south around the border, where only as yet this bed has been well observed. In the deep 

 borings, within the basin, it has frequently been found to be wanting ; the lowest seam 

 not being a continuation of No. 1. For convenience and brevity, I shall, however, desig- 

 nate the beds by numbers, having stated that one is not to be regarded as the geological 

 equivalent of another, because the number is the same. 



ELEVATION OF POINTS IN THE LOWER COAL SEAM. 



Curtis' old entry (1838), Brookfield . . ..... 426 feet. 



Mineral Ridge (Ward's old bank), Weathersfield ..... 369 feet. 



Girard banks on Four-mile Run, lowest part ...... 295 feet. 



Briar Hill, bottom of sump shaft . ....... 318 feet. 



Dr. Manning's old entry near Youngstown ....... 332 feet. 



Powers' bank, three miles below Youngstown ...... 285 feet. 



Mount Nebo, near Lowell, lowest part ....... 222 feet. 



