MONONGAHELA FORMATION 



227 



H. D. Roger in 1840* for the Upper Coal Measures as exposed in the 

 valley of the Monongahela river. The name has had a varied usage 

 since then, part of the time being employed in a broader sense to include 

 the upper half of the Coal Measures. The U. S. Geological Survey in its 

 Piedmont folio has em ployed s the term Elkgarden formation for all of 

 the beds above the base of the Pittsburg coal. 



Pittsburg coal (45). — At the base of the MonoDgahela formation is the 

 seam of coal known locally as the u Big vein " or " Fourteen-foot " coal 

 This seam in its stratigraphic relations to the overlying and underlying 

 beds corresponds exactly to the Pittsburg coal. The fauna of the roof 

 shales, as far as our present knowledge goes, is the same. Dr I. C. 

 White f has pointed out the identity of structure within the bed. The 

 following sections showing the resemblance of the bed in the type locality 

 to a typical Georges Creek section are quoted from Doctor White's paper : 



Section of the Pittsburg Coal at Lonaconing 



Inches 



" Roof" coal, with slate parting below 20 



" Breast " coal, 6 inches of bone on top 91 



Slate x 1 



1 ' Bearing-in " coal 4J 



Slate Of 



"Brick" coal 16 



Slate Ok 



"Bottom " coal 15 



Section of the Pittsburg Coal at the Ormsby Mine, Pittsburg 



Roof" \ 



Inches 



Coal 6 



Clay 2 



Clay 8J 



Parting 0£ 



Coal. 2 



Clay 9 



Coal 8 



Parting 0J \ 56 



Coal 9 



Clay 0J 



Coal 5 



Parting 0J 



Coal 2 



Parting 0% 



L Coal 2 



* Fourth Annual Report of the Geological Survey of the State of Pennsylvania, p. 150. 

 fThe Pittsburg Coal Bed, Amer. Geol., vol. xxi, pp. 49-60. 



