128 J. J. STEVENSON — CARBONIFEROUS OF APPALACHIAN BASIN 



with the Etna coal bed, thin and worthless, underlying the sandstone. 

 Farther south 20 feet of the Bonair remain in place at only 30 feet above 

 the Etna. The latter rock decreases in thickness locally, for at a little 

 more than 20 miles from the state line it is but 30 feet, with the " Cashie " 

 coal bed at 22 feet above it. Respecting the rock at this place, Mr Mc- 

 Calley says : " For several feet up in this Lower Conglomerate, from its 

 base, there run streaks of hard cubical coal, rilling cracks in the con- 

 glomerate; the thicker of these coal seams sometimes divide up into 

 many coal streaks." In the extreme southern part of Jackson county, 

 near the Marshall line, both conglomerates are shown, each 50 to 60 feet 

 thick, separated by an interval of only 10 feet, including the Cashie coal 

 bed. 



Mr McCalley gives a number of sections in Marshall county south 

 from Jackson. The interval between the conglomerates increases, so that 

 at the Blount county line it is 70 feet, with the Cashie coal bed persist- 

 ent. The Etna coal bed is triple, and the interval from the top of the 

 Etna sandstone to the Lower Carboniferous limestone has decreased to 

 140 feet — little more than one-fourth of the thickness at the Georgia 

 line. 



On the easterly side of Raccoon mountain the Bonair is 75 to 80 feet 

 at Browns gap, 2 miles from the Georgia line, where it is massive and 

 almost wholly pebbles. The interval to the Lower Carboniferous is ap- 

 proximately 300 feet, showing a rapid decrease within a few miles south- 

 east. In this region the Etna is a mass of pebbles, but farther south it 

 is less pebbly, and in places is merely a cross-bedded sandstone. The in- 

 terval between the conglomerates increases southward until it becomes 

 90 feet in northern Etowah county, south from Marshall. The Cashie 

 and Etna coal beds persist in the sections, but they are usually thin, 

 rarely reaching workable thickness.* 



Raccoon mountain is divided in Blount and Etowah counties by Mur- 

 phrees valley, originating near the north line of Etowah and passing- 

 southwest through Blount until it unites with the Coosa or Birmingham 

 valley, which topographically is a continuation of Wills valley. The 

 portion lying between these valleys is known as Blounts mountain, 

 while that west from Murphrees to Browns (Sequatchie) valley retains the 

 name of Raccoon mountain. The conditions in Blount mountain, as 

 described by Mr Gibson, contrast strangely with those in the area farther 

 north. It is evident that the thicknesses assigned by him to some of the 

 beds are merely estimates and in excess, but it is equally evident that 

 there is an abrupt thickening of the whole column. 



* H. McCalley : Op. cit., pp. 44, 45, 47, 48, 4i), 50, 52, 57, 75, 81, 82, 107. 



