406 INDEX TO THE STRATIGEAPHY OF NOETH AMEEICA. 



Stevenson"*® comments on the fact that the formations represented in Alabama 

 are recognizable far to the north and northeast, although they undergo very material 

 lithologic changes, and he thus sums up the relations : 



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

 hmestone and markedly siliceous; the Hartselle, sandstone 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 argUlaceous in northern 

 Tennessee, where its upper portion has been identified with the Pennington shale. In Ken- 

 tucky the Tuscumbia and HartseUe are taken together as the St. Louis, but they retain the 

 Tennessee features, one of the HartseUe sandstones being persistent. The Bangor becomes 

 very shaly and, like the Tuscumbia, thins out northward more rapidly than the Hartselle, so 

 that the last alone is present in central Ohio, where Prof. Andrews called it the MaxviUe. 



Along the eastern outcrop one finds greater variation, for outlying areas toward the south- 

 east reveal something of the conditions existing along the old shore line. But those areas may 

 be neglected in this connection. Following the border of the principal areas, one finds the 

 Tuscumbia, HartseUe, 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, whUe at least one of the HartseUe sandstones is persistent in southern 

 Virginia; but the Bangor, the upper portion of Mr. Hayes's Bangor limestone, becomes increas- 

 ingly argUlaceous northward, so that frequent reference is made to its tendency to weather into 

 shale. Toward the Virginia line it becomes almost whoUy shale and sandstone, while it 

 increases greatly in thickness, so that Mr. Campbell has separated the Pennington shale from 

 the hmestone which he calls Newman. The enormous increase in thickness of the section, due 

 to increase of land detritus, renders exact tracing difiicult for a little way in southwest Virginia, 

 the more so since detaUed descriptions have not been published. The Bangor evidently becomes 

 wholly shale and sandstone before New and Greenbrier rivers are reached, where Fontaine and 

 Campbell found so great a mass of shales with insignificant streaks of limestone. The persist- 

 ence of the HartseUe sandstone at the bottom of the shales or near the top of the limestone is 

 shown by many of the oU records and along the outcrops almost into Pennsylvania. The 

 upper limestone of Virginia, Maryland, and Pennsylvania is the HartseUe. The Tuscumbia 

 retains its sUiceous character throughout, though losing its chert in Virginia and becoming 

 merely a sUiceous limestone; this feature, along with a curiously current-bedded structure and 

 a peculiar whiteness when crushed, characterizes it thence into Pennsylvania, where /by several 

 of the geologists it was termed the SUiceous limestone. 



The correlation seems to be : 



Shenango [shak]. — Bangor of McCalley in Alabama; upper portion of Bangor of Hayes in Tennessee; upper portion 

 of Safford's Mountain limestone in Tennessee; Chester of Kentucky geologists (Second Survey); Pennington and top of 

 Newman of Campbell in Tennessee and southwest Virginia; Umbral shales of Fontaine; Canaan shales of Darton; 

 Greenbrier shale of W. B. Bogers; Mauch Chunk shale of Maryland; Mauch Chunk of Pennsylvania in part; absent 

 from most of Ohio; Shenango shale of I. C. White in northeast Ohio and northwest Pennsylvania. 



MaxviUe. — Hartselle of Alabama; greater part of Bangor in Tennessee; lower part of Mountain limestone in Ten- 

 nessee; greater part of upper Newman and of upper Greenbrier in Virginia; upper Umbral and upper Mauch Chunk 

 limestones in Pennsylvania; Maxville of Ohio; upper St. Louis of Kentucky. 



Tusawmhia. — Tuscumbia of McCalley in Alabama; Lithostrotion of Safford in Tennessee; upper part of Fort Payne 

 in Tennessee; lower part of St. Louis in Kentucky; lower Newman and Greenbrier in Virginia; lower [part] of Green- 

 brier in Maryland; Siliceous limestone of Pennsylvania; absent in Ohio except at Kentucky border. 



The term Shenango is the earliest applied definitely to the latest division. Though Dr. 

 White's Shenango shales have been spoken of as representing the whole of the Mauch Chunk 

 sedimentation, it will be shown in the next chapter that they represent practically only the 

 sedimentation of the closing epoch. The name MaxviUe was given by Prof. Andrews in 1870 



