CORRELATION OP CONEMAtTGH FORMATION 159 



or perhaps representing at the east a horizon which at one place in 

 western Pennsylvania shows a trace, of coal. 



Several sandstones have been recognized and have received names. 

 The Connellsville sandstone of J. P. Lesley seems to be fairly per- 

 sistent, as sandstones go, along the eastern side in Fayette and West-, 

 moreland counties of Pennsylvania as well as in West Virginia; but 

 the name is useful chiefly to designate the interval between the Little 

 Pittsburg and Little Clarksburg coal beds. One usually finds some sand- 

 stone in this interval, often thick and sometimes conglomerate. The 

 Morgantown sandstone of J. J. Stevenson is a more noteworthy deposit 

 in the interval between Little Clarksburg and Elk Lick coal beds. This 

 is remarkably persistent in the eastern half of the basin, and not infre- 

 quently some sandstone is present in this interval at Ohio localities. It 

 varies greatly in thickness, at times extending upward as sandstone into 

 the Connellsville interval or downward to below the Ames limestone, while 

 again the whole interval is occupied by shale. Ordinarily it is moder- 

 ately coarse, at times even conglomerate, and usually so well cemented as 

 to be a durable building stone. It is the first oil rock of Greene county, 

 Pennsylvania. Somewhat lower down is the Cowrun sandstone of the 

 Ohio oil-well drillers overlying the Anderson coal bed. It marks the" 

 interval between the Barton coal bed and the Cambridge limestone. This 

 interval frequently shows massive sandstone along the northern outcrop, 

 at times continuous with the Buffalo sandstone below. Like all the other 

 sandstones, this is variable and often absent. It has been a somewhat 

 important oil horizon in Ohio and has yielded some oil in West Virginia, 

 where the drillers' records often note it under the name "Salzburg" 

 sandstone. The Buffalo sandstone of I. C. White (Salzburg of Stevenson) 

 is in the interval between the Cambridge and Brush Creek limestones 

 The type locality is in southwest Armstrong county, where the mass is 

 60 feet thick and conglomerate. It is persistent along tbe northern and 

 eastern outcrop in Pennsylvania and in West Virginia and a sandstone 

 is usually shown in this interval by the oil-well records of the latter state. 

 Along the western outcrop in Ohio and in Kentucky this interval usually 

 contains more or less of coarse sandstone. 



The Mahoning interval, between the Brush Creek and Upper Freeport 

 coal beds, is occupied typically by the Upper and Lower Mahoning sand- 

 stones, separated by variable shales, but at times one finds the whole 

 interval filled with shale, at others with sandstone. In much of Penn- 

 sylvania and West Virginia both sandstone plates are present, but on 

 the western side of the basin throughout the upper plate and most of the 

 intervening shale disappear, so that the Brush Creek coal bed comes down 



