WHITE.] POTTSVILLE FLORAS IN OTHER REGIONS. 817 



\'erv nearl}' contemporaneous with the same flora is that in the roof 

 of the Sharon coal in northwestern Penns^dvauia and northern Ohio, par- 

 tially described by Dr. Newberry in 1872. ^ The * ' coal-bearing- shales " 

 of Washington Count}', Arkansas, whose species, ranging usually a 

 little higher than those of the Sewanee coal, were described by Pro 

 fessor Lesquereux in his great work on the Coal Flora," can not be of 

 very much later date than the Sewanee coal, and are undoulitedly 

 representative of the Sew^^U formation. 



The lower portions of (a) the Sewell formation in the Pocahontas, 

 Raleigh, and Kanawha Falls quadrangles, of (/y) the Dismal formation 

 in the Tazewell quadrangle, and of (c) the Norton formation in the 

 Estillville and Bristol quadrangles, are included in the zone of the 

 Sewanee flora, to which in its broader sense are also referable certain 

 plant-bearing beds of the Briceville formation in the Briceville and 

 AVartburg quadrangles,^ in Tennessee. It also appears probable that 

 large parts, perhaps the greater portions, of the Pickens and Black- 

 water formations in the Buckhannon and Piedmont quadrangles,* 

 respective!}', in West Virginia, are referable to the Sewell formation 

 and are included within the Sewanee zone. However, the question of 

 the existence of the lower horizons of the Pottsville in the relatively 

 thinner sections in the Potomac region will receive particular atten- 

 tion in the later and more complete report. 



LOOKOUT FORMATION. 



In those earlier published folios of the Geologic Atlas of the United 

 States that relate to the Carlson if erous formations of the southern 

 Appalachian region the coal-bearing terranes included in the quadran- 

 gles are grouped in but two formations, the Lookout (lower) and the 

 Walden (upper). The Lookout extends from the Bangor limestone 

 (Mississippian) to the top of the great Sewanee conglomerate of Saffcrd.^ 

 The oldest plants I have yet seen from this formation on the east side 

 of the coal field, where it is thickest, are closely related to those from 

 the roof of the Dade coal in northwestern Georgia, and are clearly 

 referahle to the Mar iopteris pottsvillea zone. Whether the basal ter- 

 ranes of the formation in this region are as old as or older than the 

 Pocahontas coal or the Lykens coal No. 5 is still uncertain. It is, how- 

 ever, highly probable that in the region included in the Kingston, 

 Pikeville, Chattanooga, and Ringgold quadrangles the lowest beds of 

 the Lookout are not older than the zone of the Lykens coal No. 5. 



1 Kept. Geol. Survey Ohio, 1873, Vol. I, Pt. 11. 



2 Coal Flora, Second Geol. Survey of Pennsylvania, Report P, :5 vols, and atlas, Ilarrisburg, 1S79-1H84. 

 •■! Geologic Atla.s of the United States, folios 33 and 40. 



■• Idem, folios 31 and 28. 



•'■Geology of Tonne.s.see, 1869. p. 3(i0. 



2U GEOL, I'T 2 52 



