40 J. J. STEVENSON CARBONIFEROUS OF APPALACHIAN BASIN 



Washington, but it is shown frequently south from the line of the 

 Pennsylvania railroad in the latter county, though never more than 

 about 2 feet thick and always apparently very inferior. It is seldom 

 more than 2 or 3 feet above its bright yellow limestone and at times the 

 coal and limestone are separated by a mere parting shale. The bed is 

 present in the northern panhandle of West Virginia and is distinct in 

 western Belmont of Ohio, though wanting in Jefferson, Harrison, and 

 apparently in northern Guernsey. It does not seem to reach the north- 

 ern outcrop in Ohio, reaching northward there hardly any farther than 

 in Washington coimty of Pennsylvania; but southward it is persistent 

 as shale or coal along the western outcrop, where it is known as the 

 Hobson coal bed and is occasionally workable. It is of considerable 

 local importance in northern Monroe, where it has a somewhat complex 

 structure. It is certainly present under the Cowrun anticline in Wash- 

 ington county and northward along the Ohio river, but southward it 

 evidently disappears. It is insignificant in the exposed area within the 

 eastern part of the West Virginia field, but it is distinctly a coal bed 

 in Harrison, Doddridge, Gilmer, Lewis, and Wirt, in all of which it is 

 exposed and at times shows a structure recalling that seen in Monroe 

 of Ohio. The records of oil borings show that it is present in all 

 counties north from the Little Kanawha river except possibly Wood, 

 'where every trace of coal seems to have disappeared in this formation. 

 Its occurrence farther south is very doubtful and it is not reported in 

 any record. 



The distribution of the Uniontown contrasts notably with that of the 

 lower beds. The Pittsburg is practically absent from the great interior 

 area, though its horizon is marked often by thin coal or by carbonaceous 

 shale ; it is a thick bed on the borders of the field, thinning from all sides 

 toward the middle. The Upper Sewickley is insignificant for the most 

 part on the east side, though its place is rarely without shale or some 

 coal, but on the west side it is important, extending southward to many 

 miles beyond the Pittsburg's disappearance, though, like that bed, 

 marked only by black shale or wholly wanting in the central buried area. 

 The Uniontown, however, always thin and never attaining more than 

 purely local importance, is a well marked coal horizon west from Chest- 

 nut ridge, and even from farther east in West Virginia, across the whole 

 basin. It is a distinct coal horizon in the central part of the field, where 

 the lower beds have become indefinite, and does not disappear south- 

 wardly until one approaches the region where the Pittsburg reappears. 

 Though a coal bed in a so great area, it shows no regular variations in 

 thickness such as those of the Pittsburg, but is a thin sheet, usually 



