VIRGINIA KENDALL
LEDGES
The Virginia Kendall Ledges
(Ritchie Ledges) area of northeastern Ohio is an isolated platform of Sharon
Formation sandstones (Morrowan, upper Lower Pennsylvanian) surrounded by a
lower land surface of Cuyahoga Formation shales & siltstones &
sandstones (Lower Mississippian). The edges of the platform are
impressive cliffs of brown quartzose sandstones and pebbly sandstones with
large blocks apparently separating from the rest of the platform (joint
separation and lateral sliding of blocks or dissolution along linear
fractures?). The lower Sharon Formation's three-dimensional architecture
is readily observable at this locality. Apparent channels of pebbly
sandstones and conglomeratic sandstones are abundant. Some of the channelforms
have been interpreted as confluence scours (plunge pools at the downstream end
of an ancient gravel island in a braided stream). This locality is
world-famous for its relative abundance of overturned crossbedding (the top
portions of the crossbeds have been pushed over). There's also a very
rare example of sheath folding of sandstone crossbeds.
Overturned crossbeds in lower Sharon Formation
quartzose sandstones (Morrowan, upper Lower Pennsylvanian).
Overturned crossbeds in lower Sharon Formation
quartzose sandstones (Morrowan, upper Lower Pennsylvanian).
Honeycomb weathering developed in quartzose
sandstones of the lower Sharon Formation.
Extensive “Liesegang
banding" obscures the primary bedding features in many places.
“Liesegang banding” refers to stripes of iron oxide mineralization in porous
rocks, precipitated by moving groundwater fronts. “Liesegang banding” may
follow primary bedding features, or may cut across primary bedding geometries.
Location: Ritchie Ledges at Virginia
Kendall Park, south of Haskell Run & north of Kendall Park Road/Truxell
Road, Cuyahoga Valley National Park, north of Akron, northern Summit County,
northeastern Ohio, USA.
Some information provided by
Neil Wells.