148 J. J. STEVENSON CARBONIFEROUS OF APPALACHIAN BASIN 



be due to irregularity in distribution of sediments or even to local eleva- 

 tion or subsidence, but in many cases they are such as to suggest genuine 

 lack of conformability due to a broad elevation along the western side, 

 which, in addition, would explain the abrupt change from coarse sand- 

 stone to fine shale, if it be siipposed sufficient to divert the drainage tem- 

 porarily and to make the low interior land the important source of sedi- 

 ments. Subsidence during the Beaver seems to have been comparatively 

 uniform in the northern part of the basin, though there is evidence of 

 somewhat more subsidence in the east than in the west ; but in Kentucky 

 and southern West Yirginia the rate of subsidence increased southwardly 

 and eastwardly with notable rapidity. The shales below the Sharon coal 

 bed are but 10 feet thick at the western outcrop in Kentucky. Mr J. 

 Lesley followed them across the state, to the West Virginia border, where 

 they are 150 feet, while on the Kanawha river, in West Virginia, they 

 are 400 feet thick. This differential sinking continued throughout the 

 Beaver, for intervals above the Sharon coal bed show notable variations in 

 the southern part of the remaining area. 



In southern Pennsylvania and the immediately adjacent part of West 

 Virginia the sedimentation was continuously marine from the Shenango 

 up to the middle of the Beaver, there being no recognizable members of 

 the Beaver or older beds below the Quakertown coal bed, and the passage 

 beds are largely red shale, with locally important deposits of iron ore. 

 These contain in some places marine forms, thoroughly well developed 

 and of large size, as if living amid favorable conditions. This continuous 

 sedimentation prevailed in a broad area and leads to uncertainty in the 

 attempt to interpret oil-well records within the interior counties of West 

 Virginia, where a sandstone sometimes divides them. In northern Ken- 

 tucliy Professor Crandall found in shales below the Sharon coal bed 

 numerous calcareous concretions, apparently non-fossiliferous. These in- 

 crease in number as well as size farther south, at the same time ascending 

 in the series until in the southern part of the state they reach to what 

 has been taken by the writer to be the Mercer horizon; but concretions 

 above the Sharon coal become more and more arenaceous. Mr J. Lesley 

 observed these concretions long ago and followed them from the western 

 outcrop across the state to the West Virginia line, where they are the 

 silicious limestones of Doctor White's Winfield section. This deposit is 

 reported from Logan county of West Virginia, but thence eastward, pos- 

 sibly because of imperfect exposures, at no place until the Kanawha river 

 is reached. There one finds the concretionary Campbells Creek lime- 

 stone above, with the Stockton cement and the Eagle limestone below 

 the Sharon (Campbells Creek) coal bed. No fossils -are reported from 



