272 D. WHITE — DEPOSITION OF APPALACHIAN POTTSVILLE 



488 feet. The flora of the Pocahontas beds appears to be present near 

 the base of the deepest sections of the Southern Anthracite field*. It 

 has not }^et been recognized southwest of the Tazewell, Virginia, quad- 

 rangle, perhaps from lack of fossils from its level in this area, and though 

 it probably extends farther along the eastern border of the coal field, 

 the occurrence of large amounts of conglomerate material at the Lower 

 Carboniferous contact and the approach of the Horsepen (Middle Potts- 

 ville) floras to the base of the section render it probable that the Poca- 

 hontas formation, if present as far south as Cumberland gap, is very 

 thin in the Tennessee region.f Paleontological data are lacking to show 

 whether the Pocahontas horizon is present in the Alabama region, though 

 it would seem that the formation should be represented in so very thick 

 sections. The Pocahontas formation is confined to the eastern boundar} 7 

 of the coal region, where it lies at the base of the very thick sections. 

 Its area is provisionally indicated by the darkest shade on the map. 



HORSEPEN-RALEIGH-BON AIR OVERLAP 



The next division represented on the map includes the Horsepen group 

 and extends up to the top of the Raleigh sandstone of the New River 

 region. On paleobotanical grounds the Raleigh has been correlated 

 with the Main Sewanee (Bon Air) conglomerate of the Southern Appa- 

 lachian field and the great sandstone group under Lykens coal number 

 3 in the Southern Anthracite field.J The rocks of this division and the 

 underlying Pocahontas reach a thickness of over 1,200 feet at the eastern 

 border of the New River region. From a preliminary examination of 

 the fossil plants it seems probable that the horizon of the Raleigh is some 

 distance below the top of the Lee of Campbell and Keith along the Alle- 

 gheny front, near the Virginia-Tennessee line, and such a relation is 

 certain if the Rockwood coal lies in the Sewanee-Sewell zone, as appears 

 to be the case. In the accompanying map (plate 11) the area of Raleigh 

 deposition beyond the supposed confines of the Pocahontas is repre- 

 sented by the shade next lighter than that of the Pocahontas. 



SEWELL-SHARON DEPOSITION 



In an earlier publication I Raleigh and Bon Air were incidentally cor- 

 related with the Sharon conglomerate of the northern bituminous re- 



* Twentieth Ann. Rept. U. S. Geol. Survey, pt. 2, p. 817. 



fLoe. cit., pp. 817, 818. 



% Bull. Geol. Soc. Am., vol. C, 1895, pp. 316, 317, 318. 



Twentieth Ann. Rept. U. S. Geol. Survey, pt. 2, 1900, pp. 816, 818, 916. 

 § Twentieth Ann. Rept. U. S. Geol. Survey, pt. 2, 1900, p. 817. 



In a still earlier paper (Bull. Geol. Soc. Am., vol. 6, p. 319, 1895) the Sharon is more nearly cor- 

 rectly compared with the Nuttall. 



