

CORRELATION OF CONEMAUGH FORMATION 163 



higher horizon which, notably in Wood of West Virginia and Washington 

 of Ohio, extends well up into the Monongahela : but in probably by far 

 the greater portion of the Conemaugh area red beds are wholly absent 

 above the Morgantown sandstone. 



The horizontal expansion of the reds reached its maximum during the 

 interval between the Cambridge and Ames limestones, reaching then even 

 to the southeastern outcrop, as it exists today; thenceforward the area 

 constantly decreased until toward the close of the Conemaugh it included 

 only the several counties of West Virginia spoken of as the central area. 

 The conditions prevailing during deposit of the Pittsburg reds did not 

 return until well on in the Dunkard formation. 



The non-conformabilities within the Conemaugh are not great in ab- 

 solute measure, but they are proportionately great, for the formation 

 loses half its thickness in passing from the east to the west side of the 

 basin. This is in accord with conditions observed in the earlier forma- 

 tions, the extent of subsidence decreasing toward the west. But while 

 this decrease is noticeable in all of the intervals it is especially note- 

 worthy in the Mahoning and Morgantown, the Upper Mahoning being 

 unrepresented in Ohio and the Morgantown being insignificant, so that 

 the Ames limestone remains in Ohio, as in Pennsylvania, almost midway 

 between the Upper Freeport and Pittsburg coal beds. 



EAST FROM THE ALLEGHENIES 



The Conemaugh is somewhat more than 500 feet thick in the Broad Top 

 coal field, but above the Mahoning it is ill-exposed and available details 

 are few. A coal bed, 2 to 4 feet thick, known in Huntingdon county as 

 the Dudley, occurs at a few feet above the Mahoning in all parts of the 

 field and is about 400 feet below the bed there accepted as the Pittsburg. 

 In Huntingdon it underlies a massive sandstone, but in Bedford the 

 overlying rock for 30 feet is shale. The Mahoning is double, the section 

 in Bedford county being 



Feet 



Sandstone 50 



Goal bed 1 



Clay 3 



Sandstone 40 



The upper plate varies from coarse grained and somewhat conglomerate 

 to fine grained and even shaly, but the lower plate, 25 to 40 feet thick, 

 is usually massive and conglomerate, sometimes almost wholly made up 

 of white quartz pebbles. The coal bed known as the Speer in Bedford 

 county occasionally becomes workable, but it disappears northward and 



