DIVISIONS AND CORRELATIONS OF DUNKARD SERIES 87 



with the shales above the Waynesburg coal and ends with the Upper Washing- 

 ton limestone ; the latter includes the remainder of the series. This division 

 of the Dunkard series was originally suggested by J. J. Stevenson, 1 although, 

 according to his definition, the Waynesburg sandstone and the underlying plant 

 shales are included with the Monongahela series. The usage herein suggested 

 for Ohio has been approved and used by the United States Geological Survey 

 in the various Pennsylvania folios. 2 Each of the so-called Dunkard formations 

 is made up of a great number of more or less distinct divisions, which are 

 often traceable over very considerable areas and most of which have been 

 given definite locality names by the Pennsylvania and West Virginia Geological 

 Surveys. Many of these can be recognized in Ohio and form the basis of such 

 stratigraphic correlations, as is possible between the various parts of the 

 Dunkard basin. This division of the Dunkard into two formations is very 

 arbitrary, as the stratigraphical or even the lithological break at the horizon 

 used is not pronounced. It does, however, mark the highest level at which 

 marine or brackish-water fossils were found and probably represents the ap- 

 proximate close of the oscillations between land and marine conditions, and 

 introduces the purely land and fresh-water deposits in the Dunkard basin. 



The Washington formation varies in thickness from 230 feet in Belmont 

 County to more than 300 feet in Washington County, while to the south of 

 Marietta, where the massive sandstones are well developed, this division of 

 the Dunkard includes 2S6 feet above the Washington coal, hence is probably 

 at least 3S6 feet in thickness. The Greene formation reaches a maximum 

 thickness of about 250 feet, although it is usually much thinner and often is 

 a mere capping to the higher hills. Because of its limited distribution and 

 its position in the hills, its character is less perfectly known than is that of 

 the lower formation. Much of the topography of the region which it occupies 

 consists of quite gentle slopes, which are covered with a deep soil and often 

 well sodded. 



From Marietta southward the dividing line between the Washington and 

 Greene formations is hard to trace because of the absence of the Washington 

 limestones, but it may still be continued by use of the Jollytown coal horizon 

 or the base of the Jollytown sandstone, which probably marks the break be- 

 tween the two divisions. This sandstone stratum may be picked up at various 

 places to the south of Marietta and has occasionally been quarried for grind- 

 stones. 



A large part of the Dunkard of Ohio is to be classed as "Red Beds," although 

 the Monongahela series and even the Conemaugh are not without their red 

 shales, which in the Monongahela are often so like those of the Dunkard as 

 to make them easily confused if it were not for other well defined strata asso- 

 ciated therewith. There are but few really red sandstones, and those are 

 usually only coated red on the outside or weathered surface, in the Ohio 

 Dunkard. The red is thus almost confined to the shales. In the northern 

 part of the Dunkard covered area the red beds are to be found chiefly in the 

 Greene formation, but to the southward most of the shale in the whole series 

 is red. In the main, these shales, sandstones, limestones, and beds of coal 

 represent land and swamp or fresh-water deposits, but the presence of gypsum 



Second Geol. Survey Penna., Rept. K, 1875 (1876), pp. 34-56. 

 2 See U. S. Geol. Survey Folios Nos. 121, 180, etcetera. 



