WESTERN OUTCROPS IN ALABAMA AND TENNESSEE 77 



Lawrence, the Bangor is 350 to 400 feet. In Colbert, north from Frank- 

 lin, the Hartselle shows unexpected variations; the upper sandstone is 

 apparently 150 feet at La Grange, but it becomes thinner westwardl}^ 

 for midway in the county are two sandstones, 50 and 25 feet, separated 

 by 25 feet of limestone and overlying 75 feet of sandstone, limestone, 

 and shale; limestone predominates on the Mississii)pi border, for there 

 the upper sandstones are 30 to 40 feet and 25 feet respectively, sepa- 

 rated by 35 to 40 feet of limestone, while lower down are 60 feet of lime- 

 stone. The bottom sandstones vary from 5 to 15 feet.* 



The Fort Payne is very clearly separable into the Lauderdale and 

 Tuscumbia. In Madison both are very cherty and both contain beds 

 of limestone, but the chert of the Tuscumbia is nodular, not bedded. In 

 Limestone the Lauderdale is 175 to 225 feet, and the Tuscumbia 150 to 

 200 feet, while in Lauderdale the lower division is 175 to 250 feet, with, 

 in the northwest, a thick shale toward the bottom, which disappears 

 southeastwardly. In these counties the Lauderdale becomes more and 

 the Tuscumbia less chert}^ as one follows them westward. f 



Western outcrops in Tennessee. — Professor Safford's notes on the Missis- 

 sippian of central Tennessee are full and one has in addition, for the 

 southern counties, the resume of Mr Hayes's observations, and for the 

 extreme northern counties those of Mr Campbell. The exposure with 

 which this chapter has to do forms a broad band crossing the state from 

 south to north through Lincoln, Franklin, Coffee, Warren, De Kalb, 

 Putnam, Overton, and Pickett counties, with extensions eastward into 

 valleys within the Cumberland plateau. This band is separated by the 

 Central Basin of Tennessee from the western area of Mississippian in 

 the state, which is continuous at the south with Lauderdale and Lime- 

 stone counties of Alabama, and at the north with the western area in 

 Kentucky. The division in Tennessee is wholly due to erosion, and 

 the areas are very nearly united at both the northern and the southern 

 border of the state. As the western area is part of the Mississippi region, 

 which farther north lies west from the Cincinnati peninsula, only inci- 

 dental reference will be made to it after description of the w^est side of 

 the Cumberland plateau. 



Mr Hayes does not separate the Lauderdale and Tuscumbia — the 

 Protean and Lithostrotion of Safford — using only the term Fort Payne, 

 which includes both. He mentions that the Fort Payne is very silicious 

 at the bottom, often only chert, while calcareous matter increases up- 

 ward so as to make a gradual transition to the Bangor. The thickness 



♦Henry McCalley, vol. i, Jackson county, 323, 327 ; Madison, 140, 144; Morgan, 250, 251, 252, 258, 

 261, 26G; Lawrence, 224, 230, 234; Franklin, 190, 197 ; Colbert, 154, 157, 161, 166, 176. 

 t Henry McCalley, vol. i, Madison, 125, 126; Limestone, 115, 119; Lauderdale, 92, 103. 



