CUMBERLAND FALLS
Kentucky's Cumberland Falls
is the largest waterfall in southeastern Amercia. It is located along the
Cumberland River near the towns of Williamsburg and Corbin in southeastern
Kentucky. Water cascades downward between ~55 to ~70 feet, depending on
river level. The rocks at the falls and along the upstream &
downstream riverbanks are hard, erosion-resistant beds of the Rockcastle
Sandstone (a member of the Bee Rock Formation, aka Lee Formation,
Lower Pennsylvanian).
Cumberland Falls (panoramic view - be sure
to scroll all the way to the left). Photo provided by Mary Ellen St.
John.
Cumberland Falls (looking ~SW) - these are
the rapids immediately upstream from the waterfall. The rocks are fluvial
quartzose sandstones and pebbly quartzose sandstones of the Rockcastle
Sandstone (Lower Pennsylvanian).
Rockcastle Sandstone (looking ~SW) -
cross-bedded, fluvial, quartzose sandstones floor much of the Cumberland River
just upstream from Cumberland Falls. The cross beds are dipping upstream
(to the left), indicating the original depositional current direction.
Rockcastle Sandstone - this unit's lithologies
range from cross-bedded quartzose sandstones to pebbly sandstones to
conglomeratic sandstones to conglomerates. Almost all the pebbles are
composed of quartz, and are dominantly subrounded in shape. These
features indicate that the Rockcastle was deposited in an ancient fluvial
(river) setting.
Coal gravel bar - abundant, river-worn
pebbles of Pennsylvanian-aged bituminous coal occur in gravel bars upstream
from Cumberland Falls. Some geologic literature I've examined suggests
these are naturally occurring. The Barren Fork Coal outcrops in the
hillsides along the river here. However, the park service at Cumberland
Falls doubts that the coal gravel is natural, and encourages visitors to
collect samples. Regardless, this is an interesting sight. This is
not an everyday river clast lithology!