446 ORIGIN OF THE APPALACHIAN COAL STRATA, 



Kenawha, which it crosses Ijctwcen Chavlcslown and the 

 Pocatalico creek. From the Kenawha, it ranges nearly west to 

 the Ohio river, between Guyandotte and Burlington, where, 

 crossing that gi-eat stream into the state of Ohio, it sweeps rapid- 

 ly north. Its outcrop, now following the western margin of the 

 basin, preserves a general north-northeast direction as far as 

 McConnelsville,on the Muskingum. Beyond this point it stretch- 

 es in a northeasterly course, until it recrosses the Ohio river a 

 litde above Steubenville, where it soon reaches the western line 

 of Pennsylvania, in Beaver county. Here the edge of the seam 

 turns eastward, and crosses the Ohio river once more, a few miles 

 below Pittsburg, and the Allegheny river, some miles northeast of 

 that town. East of this point, it pursues a more devious line, 

 the meanderings of wiiich are caused by three parallel anticlinal 

 axes, crossing the Kiskiminitas and Conemaugh rivers. Being 

 thrown into a very irregular and curving outcrop by these eleva- 

 tions, it finally joins the southeastern margin, at the northeast 

 extremity of the basin, in Indiana county, the point from which 

 we set out. The longest diameter of the gi'eat elliptical area here 

 delineated, is very nearly two hundred and twenty-five miles, and 

 its maximum breadth about one hundred miles. The superficial 

 extent of the whole coal-seam, as nearly as I can estimate it, is 

 about fourteen thousand square miles. 



But the limits here described, though wide, fall very far within 

 those which the bed anciently occupied. To the southeast of the 

 large basin of the Ohio river, there are several other insulated, 

 parallel trouglis, which also contain the Pittsburg seam. Of 

 these, the furthest from the main coal-field is that at the head of 

 the Potomac river, at a distance of about forty-three miles in a 

 straight line. The eastern margin of the Pittsburg bed is here, 

 however, nearly fifty miles east-southeast of the eastern edge of 

 the same seam, in the main or western basin, and it has a corres- 

 ponding expansion eastward, in other districts. That this coal- 

 bed preserv^es an unbroken range for many miles to the northeast 

 of the termination of the principal basin, in Indiana county, ap- 

 pears highly probable, from a comparison of the coal-measures at 

 certain localities in that quarter. I shall not, however, assume 



