126 J. J. STEVENSON — CARBONIFEROUS OP APPALACHIAN BASIN 



Before proceeding further with the Waldens Ridge area in Tennessee, 

 it is necessary to review summarily the conditions in Alabama. 



ALABAMA 



The Cumberland plateau of Mr McCalley lies north from the Tennessee 

 river and west from Sequatchie or Browns valley, thus including parts 

 of Jackson, Madison, and Marshall counties. 



Mr McCalley takes as the basis of comparison the section obtained b}' 

 Professor Colton at Etna and that by Professor Safford in southeastern 

 Franklin county, both within 2 or 3 miles of the Alabama line. The 

 Bonair conglomerate (Upper or Main of Safford) is the highest rock in 

 most of this area and forms the " Second bluff,'' the " First " or " Lower 

 bluff" being that of the Etna (Cliff) sandstone, commonly called the 

 " Millstone grit." As in Tennessee, these conglomerates vary from coarse 

 quartzose sandstones to pebbly rock and are separated by an interval of 

 25 to 150 or more feet. The Lower Measures, underlying the Etna sand- 

 stone, are rarely more than 50 feet thick in the plateau, though in other 

 portions of the state they appear to be thicker than in any portion of 

 Tennessee. 



The outliers in Madison county are farther west than those of Franklin 

 in Tennessee. The Etna, the highest bed in most of Madison, is a mass- 

 ive sandstone without pebbles and not more than 75 feet thick ; at the 

 western exposures it rests directly on the Etna coal bed and the interval 

 to the Lower Carboniferous limestone varies from 2 to 20 feet. In north- 

 west Jackson, the Etna sandstone, 50 to 80 feet thick, overlies the Etna 

 (Cliff) coal bed, which is 2 to 10 feet above the limestone, but on Poor 

 House mountain the interval is 60 feet; on Keel mountain, farther east, 

 both Bonair and Etna are shown with the Etna, coal bed represented by 

 several layers distributed through 20 feet of section. At Limerock, in the 

 southern part of the county, the Lower Measures are much thicker ; thus 



Feet 



1. Cliff rock [Etna] 70 



2. Cliff coal seam [Etna] 4 



3. Fireclay , 4 



4. iShale and sandstone 200 



5. Coal and fireclay 1 to 3 



6. Heavy bedded sandstone 25 



7. Concretionary sandstone 12 



giving 247 feet below the Etna sandstone. No details are available for 

 Marshall county.* 



* H. McCalley: Geol. Survey of Alabama, Coal Measures of Plateau region, 1891, pp. 25, 30, 31, 32, 

 38, 59. 



