80 J. J. STEVEXSON — LOWER CARBONIFEROUS, APPALACHIAN feASlN 



Central Basin only the silicious orroup as in I^auderdale, Limestone, and 

 most of Madison in Alabama. The whole area is bounded at the west 

 practically by the Tennessee river, and the Tuscumbia or Lithostrotion 

 is confined almost wholl}^ to the region north from the Cumberland 

 river. At Clarksville, in the northern part of the area, tlie Lithostrotion 

 bed shows : 



Feet 



1. Not exposed 30 



2. Limestone, slightly cherty 15 



3. Limestone, no chert, lower third, ooHte 120 



4. Limestone, more or less cherty 30 



The extreme thickness in the northwest corner is about 250 feet, and 

 the limestones contain nodular chert. Tliere is a contrast with the 

 Overton County section, for there the upper 128 feet is largely cherty, 

 while in this western area the chert is insignificant.* 



Western outcrops in Kentucky. — In northern Kentucky the Appala- 

 chian and Mississippian areas are separated bj^the Cincinnati peninsula, 

 beyond whose southern termination to the Tennessee line the separation 

 continues, as erosion has removed all rocks newer than the Devonian. 



Unfortunately not much of detail is available with reference to Ken- 

 tucky. The early survey under Doctor Owen ended abruptly with his 

 death, in 1860. Up to that time the work had been very largel}' that of 

 reconnaissance, and such detailed work as had been done was almost 

 wholly economical, so that the references to Lower Carboniferous de- 

 posits are little more than incidental. The same remarks apply almost 

 equally to the second surve}^, which was prosecuted with much energ}^ 

 to determine as rapidly as possible the coal and iron resources of the 

 state. There is lack of information respecting the limestone, so that 

 one finds difficulty in carrying forward to the Ohio river the differentia- 

 tion of formations seen so clearly in Alabama and Tennessee. Enough, 

 however, is afforded by the scattered observations in the several coun- 

 ties to make the general conditions clear. 



Clinton county of Kentucky adjoins Pickett of Tennessee. Mr Lough- 

 ridge's section in this county shows the groups as in Tennessee, but with 

 decreasing thickness of the Bangor. His section on Poplar mountain, 

 in the eastern portion of the county, shows — the subdivision and the 

 nomenclature being ours : 



1. Bangor: Feet 



Shales and marls 1 30 



Limestone 73 



* J. M. Safford : Cp. cit., pp. 340, 345. 



