1912.] STEVENSON— THE FORMATION OF COAL BEDS. 467 



part of that county a massive pebble rock extends at times to almost 

 lOO feet above the Waynesburg coal bed. Within the oil region of 

 the same county the Waynesburg is represented by 28 feet of pebble- 

 rock. In Athens and Meigs it is a coarse sandstone, at times a 

 pebble-rock in the latter county, where it becomes continuous with 

 the southern outcrop in West Virginia. 



The Waynesburg sandstone can be traced almost uninterruptedly 

 around the Washington area ; it extends many miles farther south 

 and west into the interior than does the Pittsburgh sandstone ; on the 

 western outcrop it is coarser than that deposit and shows the pebbly 

 layers much farther northward, while it extends many miles farther 

 eastward. The north-south area, in which it is not recognizable dis- 

 tinctly by comparison of drillers' records, is not more than 50 miles 

 wide and 100 miles long. The rock varies in structure, often abruptly, 

 so that within a very short distance the topography may change from 

 rude to gentle outlines ; but the variations are like those of other 

 sandstones. The conglomerate bands and occasional areas of con- 

 glomerate rock on the western outcrop indicate that the source of 

 the Pittsburgh pebbles had become more available. The presence of 

 conglomerate and very coarse sandstone at Pocatalico on the south- 

 east outcrop certainly indicates a source of pebbles not far away, 

 but the occurrence may indicate also a buried valley. 



The higher sandstones of the W^ashington are very indefinite at 

 the north, where the changes are so frequent that the beds must 

 be taken as lentils of no great extent ; but the Marietta sandstones 

 of I. C. White are in the southwestern part of the area, where, in 

 earlier times, only irregular deposits existed. This group was named 

 because quarried near Marietta on the Ohio River in Washington 

 county of Ohio; but it is recognizable for scores of miles in each 

 direction within the Central area, where red shales are the striking 

 feature, where the earlier sandstones have disappeared to be replaced 

 with the red shale containing lentils of sandstone. They indicate 

 extensive exposures of coarse rock at the southwest and west. 



Sandstones of the Greene or closing formation of the Penn- 

 sylvanian tell even more clearly of the changing conditions. The 

 great Fish Creek and Gilmore sandstones near the top of the forma- 

 tion occupy the middle line of the area from their northern outcrop 



