MONONGAHELA FORMATION 37 



divisions with varying intervals. There, as in JefEerson and eastern 

 Belmont of Ohio, it is unimportant; but in western Belmont and Har- 

 rison it becomes more important than the Pittsburg. In much of Ohio 

 it is the chief source of suppl}^, although its coal usually contains more 

 ash than that of the Pittsburg. Where best developed it is a triple 

 bed, the middle bench being thick, the other, separated from it by thick 

 clay partings, being too thin to be worked. It extends much farther 

 eastward into the barren area than the Pittsburg does ; it is the important 

 Macksburg coal of southern Noble and northern Washington at 25 miles 

 southeast from the disappearance of the Pittsburg ; but it becomes irregu- 

 lar and of little value further toward the middle of the trough. It is 

 insignificant in West Virginia, but a trace of it was seen on the Balti- 

 more and Ohio railroad west from Clarksburg, in Harrison county, and 

 it may be the coal reported in some records termed the Sewickley in 

 the following pages. While the horizon is well marked in much of 

 Pennsylvania and occasionally carries workable coal in small areas 

 there, as in Maryland, it is most thoroughly characteristic of the westerly 

 side of the trough, where within its present area it has more coal than 

 the Pittsburg. Judging from conditions shown by the latter bed, which 

 reaches 9 feet on the western outcrop in Morgan county, one should 

 expect the Upper Sewickley to increase greatly toward its western out- 

 crop; but the contrary is true, as, accordingly to Professor Brown, the 

 Upper Sewickley "is thin and unsteady and of little economic value" 

 in western Morgan, whereas it is important in eastern Morgan as in 

 Noble, southeast Muskingum and southern Guernsey. But is a coal bed 

 to the western outcrop. 



The Sewickley horizon was characterized by local irregularity of de- 

 posit. Eeference has been made to the disappearance of the Sewickley 

 sandstone and its rapid reappearance in southern Fayette of Pennsyl- 

 vania. In southern Greene county, Doctor White found the Lower 

 Sewickley, 4 feet 10 inches thick and in several benches; but at half a 

 mile away these benches are distributed in a vertical space of 33 feet 

 6 inches. On Wheeling creek, 3 miles east from Wheeling, West Vir- 

 ginia, the section is: 



Upper Sewickley coal bed: 



Feet Inches Feet Inches 



Coal 1 2 1 



Fireclay, sandstone 6 4V.8 6 



Coal and shale 1 ( 



Clay and Sewickley sandstone 14 



Lower Sewickley coal bed 1 8 



