230 CLARK AND MARTIN — THE COAL MEASURES OF MARYLAND 



and in its regular stratigraphic sequence, it is regarded as the Waynes- 

 burg coal. In the Report on the Geology of Allegany County it was named 

 the Koontz coal, from its occurrence at the mining village of that name 

 near Lonaconing. The identity of this seam with the Waynesburg seams 

 now appears so certain that the name Koontz will be considered as a 

 synonym. The upper part of this coal is the top of the Monongahela 

 formation. 



DUNKARD FORMATION 



Composition and relations. — The strata here referred to the Dunkard 

 formation have an extreme thickness of 390 feet in Maryland. It is 

 evident that the entire formation is not represented. The present area 

 of the Dunkard deposits in Maryland is restricted to a few small tracts 

 in the central part of the Georges Creek basin. The surface has so little 

 relief that there are few good exposures, and it is almost impossible to 

 obtain a detailed section. In consequence the stratigraphic sequence is 

 very imperfectly known. 



The Dunkard formation was named by Dr I. C. White in 1891 * from 

 Dunkard creek, in southwestern Pennsylvania. The rocks of this for- 

 mation had before been known as the " Upper Barren Coal Measures " 

 or "Upper Barren Measures," and they were divided into the " Green 

 County group " and the " Washington County group." As will be noted 

 below, the strata in Maryland belong almost exclusively to the latter 

 division. 



Waynesburg sandstone (56). — A sandstone of no very great prominence 

 occurs a short distance above the Waynesburg coal. It probably repre- 

 sents the Waynesburg sandstone, since its stratigraphic position is the 

 same. 



Waynesburg "A " coal (57). — A thin coal which corresponds in position 

 to the Waynesburg "A" coal of Pennsylvania and West Virginia is found 

 on top of the Waynesburg sandstone, and about 45 feet above the 

 Waynesburg coal. 



Washington coal (58). — About 75 feet above the Waynesburg "A" coal, 

 and separated from it by an interval consisting in Maryland apparently 

 of shales and limestones, is a seam of coal whose character is not well 

 known. The thickness of this coal is 4 feet or less, but its quality is not 

 known. This coal corresponds in position to the Washington coal of 

 Pennsylvania. 



Upper Washington limestone (59). — A bed of limestone approximately 

 4 feet in thickness occurs about 170 feet above the Washington coal, and 



♦ Stratigraphy of the Bituminous Coal Fields of Pennsylvania, Ohio, and West Virginia. Bull. 

 No. 65, U. S. Geological Survey, p. 20. 



