BEDDING-PLANE EXPOSURES IN A COARSENING-UPWARD SEQUENCE, BREATHITT FORMATION, EASTERN KENTUCKY.
Stephen F. Greb and Dona.ld R., Chesnut, Jr., Kentucky
Geological Survey, Lexington, KY 40506-0107

Exposures of bedding planes in a coarsening-upward sequence of the Breathitt
Formation at the Laurel Dam spillway in Whitley County were analyzed by surveying
a 250,000 square foot area on a 10-foot-grid and mapping within grids.
	The lower boundary of the sequence is a black shale with marine trace fossils
along the basal contact where the shale fills abandoned troughs in the underlying
sandstone. The shale contains sandy lenses near the top but is truncated by
Facies Sr. Facies Sr is dominated by asymmetric current ripples and was deposited
over a broad sand flat with currents curving southward into a series of
asymmetrical troughs. Facies Sr is truncated by small channels of Facies So.
Channel fills consist of a siderite-pebble lag and massive sandstone grading
upward into ripple-bedded sandstones similar to Facies Sr except for a westward
shift in paleocurrent direction and the abundance of upper-flow regime structures.
One channel was filled with a clay plug. Facies So is, in turn,. truncated by the
larger Facies Sg channels that apparently bifurcate at the spillway. Facies Sg
channels contain plant-debris lags and abundant planar-tabular crossbeds deposited
by paleocurrents to the west.
	Analysis of bedding planes within this coarsenlng-upward sequence shows that
instead of simple gradational increases in paleocurrents, there is considerable
internal variation within units and considerable change in paleocurrent dIrection,
even in a section that was apparently fluvially dominated.