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Alluvium (Qa)
Topography
The alluvium forms terraces and floodplains along the Green River and
tributaries.
Hydrology
Most wells in the alluvium furnish less than 100 gallons per day, inadequate
for a domestic supply. A few wells in the Green River Valley yield enough
for a domestic supply.
Caseyville Formation (Pca)
Topography
The Caseyville forms dissected uplands and ridgetops near the Green
River.
Hydrology
Wells in uplands generally are inadequate (yield less than 100 gallons per day)
for a domestic supply.
Ste. Genevieve Limestone (Mgl)
Topography
The Ste. Genevieve underlies rolling karst areas. It forms steep bluffs
near the Green River.
Hydrology
The Ste. Genevieve yields more than 50 gallons per minute to wells from
large solution openings in karst areas. Most wells penetrate solution
openings, but in areas high above perennial streams these solution openings
are dry in late summer and fall, and many wells are inadequate. Wells
that do not intersect karst conduits generally are inadequate for domestic
use. Springs having low flows ranging from less than 10 gallons per
minute to more than 1,500 gallons per minute occur at or near stream
level or near the contact with the underlying St. Louis Limestone.
St. Louis Limestone (Mgl)
Topography
The St. Louis underlies rolling karst areas, but commonly has less relief
than karst in areas underlain by the Ste. Genevieve Limestone. Resistant
siltstone and nonresistant shale layers form discontinuous minor benches
on hillsides.
Hydrology
The St. Louis yields more than 50 gallons per minute to wells from large
openings in karst areas. Most wells penetrate some solution openings,
but where openings are small or high above perennial streams, yields
are often inadequate for domestic supply. Yields of wells close to major
streams are large where solution openings are penetrated. A major spring
horizon occurs near the top of the formation in the karst areas. Many
seepage springs occur throughout the formation; low flows range from
less than 10 gallons per minute to more than 1,000 gallons per minute.
The lower part of the formation is composed of siltstone and argillaceous
limestone. Yields from these rocks are low and generally not adequate
for a domestic supply.
Salem, Warsaw, Harrodsburg Formations (Msh)
Topography
These formations underlie gently rolling uplands. They form steep bluffs
where the limestone overlies rocks of Osagean age. In some areas numerous
small sinkholes occur in the Warsaw.
Hydrology
These formations yield enough water for a domestic supply where they
are dominantly limestone and close to perennial stream level. Yields
are low where siltstone or argillaceous limestone is penetrated. A minor
spring horizon occurs at the contact of the limestone with the underlying
siltstone or argillaceous limestone. Another spring horizon occurs near
the contact of the Warsaw and Fort Payne; low flows are generally less
than 5 gallons per minute.
Fort Payne Formation (Mbf), limestone bodies within Fort Payne (ls),
Knifley Sandstone Member (Mfk)
Topography
The Fort Payne underlies dissected rolling uplands and forms steep valley
sides in maturely dissected topography. Small valleys are steep and
V-shaped. Siltstone and chert form discontinuous ledges on hillsides.
Hydrology
Wells in lowland areas close to streams produce enough water for a domestic
supply and may produce more than 5 gallons per minute from solution
openings. Most wells obtain water from perched or semiperched water
bodies supported by discontinuous shale layers, and many are dry during
late summer and fall. Minor spring horizons occur throughout the formation.
Flows are as much as 30 gallons per minute, but most go dry in late
summer or fall. Where shale layers are conspicuous or when the formation
consists predominantly of siltstone, most wells are inadequate for domestic
use (less than 100 gallons per day). Where chert layers are thick and
areally extensive, yields of more than 5 gallons per minute may be obtained.
Borden Formation (Muldraugh (Mbf), Halls Gap, and Nancy Members
(MDbb) )
Topography
The Borden underlies moderately to highly dissected rolling uplands.
It forms a major escarpment in Taylor County and in Casey County, where
it is modified by faults. It forms erosional remnants, or knobs, along
the escarpment and steep bluffs along rivers.
Hydrology
Wells near streams produce enough water for a domestic supply. Most
wells obtain water from perched or semiperched water bodies supported
by discontinuous shale layers, and many are dry during late summer and
fall. Minor spring horizons occur throughout the formation. Flows are
as much as 30 gallons per minute, but most go dry in late summer and
fall. Where the formation is predominantly of siltstone, most wells
are inadequate for domestic use.
Borden Formation (New Providence Shale Member) (MDbb)
Topography
The New Providence Shale Member of the Borden Formation forms moderate
to steep slopes near base of escarpment and knobs.
Hydrology
The shale yields little or no water to wells.
Chattanooga Shale (MDnb)
Topography
The Chattanooga Shale forms steep slopes near the base of the escarpment
and knobs. It underlies small round hills near the base of the escarpment.
Resistant layers form small discontinuous ledges and minor waterfalls
in streams.
Hydrology
The shale generally yields little or no water to wells. Seepage springs
are present at numerous
horizons, but most go dry during late summer and fall.
Boyle Dolomite (MDnb)
Topography
The Boyle forms resistant ledges on valley sides between shale slopes
above and below.
Hydrology
The Boyle yields almost no water to drilled wells, but does yield water
to many small perennial
springs. Water is hard but otherwise of good quality.
Drakes and Ashlock Formation and Calloway Creek Limestone (Odf)
Topography
Shale and limestone layers form discontinuous ledges along hillsides
in some areas.
Hydrology
In lowland areas bordering larger streams, these formations yield enough
water for a domestic supply (more than 500 gallons per day) to wells.
Elsewhere, they yield little water to wells. They do yield small quantities
of water to springs. Deep wells generally yield sulfurous water or brines.
The U.S. Geological Survey's Hydrologic
Atlas Series, published cooperatively with the Kentucky Geological
Survey, provides hydrologic information for the entire state.
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