ORIGIN OF THE MIDDLESBORO MEMBER OF THE LOWER PENNSYLVANIAN-AGE LEE FORMATION (BASHKIRIAN) IN THE CENTRAL APPALACHIAN BASIN, EASTERN USA, AND ITS UNIQUE FOSSIL OCCURRENCE.
Chesnut, D. R., Kentucky Geological Survey, Lexington, Kentucky 40506,
USA; Cobb, J. C., Kentucky Geological Survey, Lexington, Kentucky 40506,
USA; and Gastaldo, R. A., Auburn University, Aurburn, Alabama 36849, USA.

The Middlesboro Member of the Lee Formation is an Early Pennsylvanian
(Namurian, Bashkirian) sandstone in the central Appalachian Basin in
Kentucky, Tennessee, and Virginia, eastern USA. Outcrops on Pine Mountain
in Tennessee indicate well-defined channel and floodplain facies. The
channel facies is composed of very poorly sorted, lithic, subarkosic
sandstone in thick, irregular, massive to cross-stratified beds. It has a
scoured base and consists of a poorly developed fining-upward sequence that
contains several types of stem and branch fossils. The floodplain facies
is composed of shale, siltstone, coal, and underclay. It contains abundant
organic debris, plant fossils, and rooting. Nearly 15 meters of the
floodplain facies were eroded by the channel. Burrowing and marine fossils
were not found in either facies.
	An extraordinary occurrence of numerous erect structures in the basal
beds of the channel facies appears to be plants preserved as sandstone
casts. These probable plant fossils are several meters tall and occur in
groups. The structures may represent a stand of pteridosperms.
Preliminary findings suggest that the erect plants are composed of aerial
stems with attached lateral appendages and adventitious roots. Other
explanations for these unique features, such as burrows, do not appear to
fit available data.
	According to sedimentological evidence, the origin of this sandstone
was a bedload-dominated fluvial system of low sinuosity with subsidiary
overbank and peat-swamp deposition. Although the origin of this unit has
been controversial, with both marine and terrestrial models being
advocated, the evidence from this occurrence strongly supports a
terrestrial fluvial environment of deposition.