916 FLORAL ZONES OB^ THE POTTSVILLE FORMATION. 



relatively few ferns, and is specially characterized by the invariable 

 abundance of a species of Neuropteris^ as well as b}' the absence of 

 the forms typical of the other zone. The Upper Lykens division 

 reveals a principal zone of the Sewanee-Sewell coal flora, typically pres- 

 ent in the vicinity of Lykens coals Nos. 3 and 2, but extending in mod- 

 ified form up to Lykens coal No. 1. The flora of the latter horizon is 

 characterized by modified survivors from the older horizons of the 

 Sewanee zone, accompanied b}^ elements apparently peculiar to this 

 portion of the section. 



10. The flora of the lower zone of the Lower L^'kens dinsion is 

 found in the vicinity of the Pocahontas coal in the very thick section 

 of the Pottsville formation in the Virg-inia-Tennessee region. It is 

 unknown in the thinner sections along the northern and western 

 borders of the Appalachian trough, Beds contemporaneous with the 

 upper zone of the same division are present in the upper portion of 

 the Clark and in the Quinnimont formations of Virginia and West 

 Virginia and in the Lookout formation of the Tennessee- Alabama 

 r(>gion. The Lower Intermediate division of the formation in the 

 Southern Anthracite field is shown b}^ the fossils to occup}-^ nearly the 

 position of the Raleigh sandstone in the Virginia region and of the 

 Sewanee conglomerate, the top of the Lookout, in Tennessee. The 

 flora (""Sewanee") in the lower portion of the Upper Lykens division 

 is essentially identical with that in the vicinit}'^ of the Sewanee coal 

 in the lower portion of the Walden sandstone in the Ala]>ama-Ten- 

 nessee region, the Sewell and the Dismal formations and a portion of 

 the Norton formation in the Virginia region, and the Sharon coal of 

 northern Penns^dvania and Ohio. The lowest phytiferous horizons 

 of the formation yet studied in the bituminous basins of Pennsylvania 

 and northern Ohio appear to be distinctly referable to this zone. It 

 is dou))tful whether ])eds older than the upper portion of the Quinni- 

 mont formation are present in these regions. The upper and less dis- 

 tinct zone of the Upper Lykens division appears to be represented in 

 the greatly expanded later modification of the Sewell formation of 

 Virginia and southern West Virginia, near the base of the Fayette 

 formation. The time of the upper 200 or 300 feet of ponderous 

 conglomeratic plates at the top of the formation, constituting the 

 Upper Intermediate division in the Southern Anthracite field, is appar- 

 ently represented b\' over 800 feet of sediments in the southern Vir- 

 ginia region, only the lower portion of which, including, probal)ly, a 

 part of the Fa^'ette formation, has the lithologic characters of the 

 Pottsville. The horizon of the well-known plant bed at (.auipliidl 

 Ledge, which is within a few feet of the supposed Mauch Uhunk. in the 

 Northern Anthracite field, is probably not lower than this division of 

 the type section. 



