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Alluvium (Qa) and Glacial Sediments (Qg)
Topography
The alluvium forms floodplains and terraces, as much as 6 miles wide,
in the Ohio River Valley; it forms broad flat areas in the valleys of
the Salt and Kentucky Rivers and large tributaries. Some Ohio River
terraces are as much as 80 feet above normal pool stage. Flats are dissected
by short, steep-sided gullies near tributaries.
Hydrology
The alluvium yields 200 to 500 gallons per minute to most wells that
penetrate the full thickness of sediment in the Ohio Valley; it yields
more than 1,000 gallons per minute to large-diameter wells. The alluvium
yields 100 to 500 gallons per day to wells in tributary-stream valleys,
and may yield more than 500 gallons per day where gravel is present.
Water is hard, and the iron content may be high near the Ohio River
Valley walls.
Devonian Limestones (Sellersburg Limestone, Jeffersonville Limestone)
(Dsj)
Topography
These limestones form broad ridges in western Oldham County.
Hydrology
These limestones yield more than 500 gallons per day to drilled wells in broad,
flat valleys or along streams on broad uplands, and yield water to springs.
Water is hard.
Louisville Limestone (Slw)
Topography
The Louisville lies in broad ridges in south-central Oldham County.
It forms cliffs and ledges in valley sides.
Hydrology
The Louisville yields more than 500 gallons per day to wells drilled
in valley bottoms or along streams on broad uplands. It yields as much
as 50 gallons per minute in places. It also yields water to springs
at the contact with the underlying Waldron Shale. Water is hard, and
may contain salt or hydrogen sulfide below stream level.
Waldron Shale (Slw)
Topography
The shale forms slopes between limestone ledges on hillsides; the erosion
of shale undermines the overlying Louisville Limestone.
Hydrology
The Waldron yields almost no water to wells or springs. It holds up
water in the overlying Louisville Limestone and prevents recharge to
the underlying Laurel Dolomite.
Laurel Dolomite (Slb)
Topography
The Laurel forms ledges and cliffs along streams.
Hydrology
The Laurel yields 100 to 500 gallons per day to wells on broad ridges
and along streams. It yields water to small springs at the contact with
the underlying Osgood Formation. Water is hard.
Osgood Formation (Slb)
Topography
The Osgood forms slopes between ledges above and below.
Hydrology
The Osgood yields almost no water from shale; it yields water to seeps
from limestone, and impedes recharge to underlying rocks. Water is hard.
Brassfield Formation (Slb)
Topography
The Brassfield forms ledges on slopes and tops of small cliffs of the
underlying Saluda Dolomite.
Hydrology
The Brassfield yields almost no water to wells. It does yield water
to seeps and small springs. Water is hard.
Drakes Formation (Saluda Dolomite, Bardstown, Rowland Members) (Od)
and Bull Fork Formation (Ob)
Topography
These formations lie in moderately dissected upland areas, with moderately
steep slopes where shale predominates and less steep slopes where limestone
predominates. The Drakes and Bull Fork form steep slopes along large
streams and cliffs; many slopes are dotted with weathered limestone
slabs. Solutional features are evident where thick limestone beds underlie
streams.
Hydrology
These formations yield 100 to 500 gallons per day to wells in large
stream valleys, and more where thick limestone is present. They yield
almost no water to wells on hillsides and ridges, except in broad ridges
in the upper part of the formation. They do yield water to small springs.
Water is hard, and may contain salt in valley bottoms, but generally
is of good quality.
The U.S. Geological Survey's Hydrologic Atlas Series, published cooperatively
with the Kentucky Geological Survey, provides hydrologic information
for the entire state. Atlases covering the county are: HA-22,
HA-97.
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