84 J. J. STEVKNSOX — LOWER CARBONIFEROUS, APPALACHIAN BASIN 



Beginning at the south on the western outcrop, one finds, ascending, 

 the Tuscumbia, limestone and markedly silicious: the Hartselle, sand- 

 stone with shales and limestones ; and the Bangor, limestones more or 

 less argillaceous. These three divisions retain their characteristics across 

 Tennessee into Kentucky, the Bangor meanwhile becoming more argilla- 

 ceous in northern Tennessee, where its upper portion has been identified 

 with the Pennington shale. In Kentucky the Tuscumbia and Hartselle 

 are taken together as the Saint Louis, but they retain the Tennessee fea- 

 tures, one of the Hartselle sandstones being persistent. The Bangor 

 becomes very shaly,and, like the Tuscumbia, thins out northward more 

 .lapidly than the Hartselle, so that the last alone is present in central 

 Ohio, where Professor Andrews called it the Maxville. 



Along the eastern outcrop, one finds greater variation, for outlying 

 areas toward the southeast reveal something of the conditions existing 

 along the old shoreline. But those areas may be neglected in this con- 

 nection. Following the border of the principal areas, one finds the Tus- 

 cumbia, Hartselle, and Bangor sharply defined in Alabama, with the 

 same features as on the western side. In Tennessee the Tuscumbia is 

 easily recognized in the upper portion of Mr Hayes's Fort Payne, while 

 at least one of the Hartselle sandstones is persistent into southern Vir- 

 ginia; but the Bangor, the upper portion of Mr Hayes's Bangor lime- 

 stone, becomes increasingly argillaceous northward, so that frequent 

 reference is made to its tendency to weather into shale. Toward the 

 Virginia line it becomes almost wholly shale and sandstone, while it in- 

 creases greatly in thickness, so that Mr Campbell has separated the Pen- 

 nington shale from the limestone which he calls Newman. The enor- 

 mous increase in thickness of the section, due to increase of land detritus, 

 renders exact tracing difficult for a little way in southwest Virginia, the 

 more so since detailed descriptions have not been published. The Bangor 

 evidently becomes wholly shale and sandstone before New and Green- 

 brier rivers are reached, where Fontaine and Campbell found so great a 

 mass of shales with insignificant streaks of limestone. The persistence 

 of the Hartselle sandstone at the bottom of the shales or near the top of 

 the limestone is shown by many of the oil records and along the outcrops 

 almost into Pennsylvania. The upper limestone of Virginia, Maryland, 

 and Pennsylvania is the Hartselle. The Tuscumbia retains its silicious 

 character throughout, though losing its chert in Virginia and becoming 

 merely a silicious limestone ; this feature, along with a curiously current- 

 bedded structure and a peculiar whiteness when crushed, characterizes 

 it thence into Penns^dvania, where b}' several of the geologists it was 

 termed the Silicious limestone. 



The correlation seems to be : 



