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Alluvium (Qa)
Topography
The alluvium forms narrow, discontinuous floodplains and small terraces
along the larger streams.
Hydrology
Generally, the alluvium is inadequate for a domestic supply, being usually
too thin and too fine grained to yield much water. Water is hard.
Breathitt Group (Pbl) (Pikeville Formation)
Topography
Tops of hills and ridges commonly are capped by sandstone in the Breathitt.
Shales form wide valleys and moderate or gentle slopes on hills.
Hydrology
The Breathitt yields more than 500 gallons per day to almost half of the wells
drilled in valley bottoms,
and more than 100 gallons per day to about half the wells drilled on hillsides
and on ridges. Sandstones
yield water to most wells. Shales also yield water to many wells, and
coal yields water to a few.
Near-vertical joints and openings along bedding plains yield most of
the water to wells. Waters
are highly variable in chemical character
Rockcastle (Plr) Sandstone Member, Grundy, Alvy Creek and Bee Rock
Formations (contains Lee type sandstone of the former Lee Formation)
Topography
These formations underlie dissected uplands in Pulaski County. Some
cliff-forming sandstone
paleochannels have been cut through shales of the Paragon Formation
into limestone units of the
Late Mississippian.
Hydrology
These rocks yield more than 500 gallons per day to about three-quarters of the
wells drilled on hillsides
and about half the wells on hilltops. In valley bottoms and lowland
areas bordering streams,
yields are greater than 500 gallons per day to more than three-quarters of the
wells. In broad upland
areas, deep wells that penetrate fractures produce enough for a domestic
supply and some may
yield as much as 5 gallons per minute. Wells in small upland areas generally are
inadequate (produce less
than 100 gallons per day). Sandstone is the principal aquifer, but shale yields
water to some wells and
coal to a few. Joints and openings along bedding planes, best developed
in sandstone, supply
most of the water to wells. Perched and semi-perched water tables are
common. Waters are
generally soft or moderately hard and contain noticeable amounts of
iron.
Paragon Formation (Mpk)
Topography
The Paragon forms moderate to steep slopes in mountain margin areas
where capped by massive
sandstone of Breathitt Group.
Hydrology
The Paragon yields almost no water. Impermeable shale may hold water
in overlying sandstone
and conglomerate.
Bangor Limestone, Hartselle Formation, Kidder Limestone (Mpk)
Topography
These formations create steep hillsides or underlie broad rolling karst
areas and dissected
uplands.
Hydrology
These rocks yield more than 500 gallons per day from solution openings. Some
wells produce more than
5 gallons per minute from large solution openings. Near outcrop areas, particularly
near major escarpments,
yields generally are inadequate during dry periods.
Ste. Genevieve Limestone (Mgl)
Topography
The Ste. Genevieve underlies dissected karst areas in uplands.
Hydrology
The Ste. Genevieve yields more than 50 gallons per minute to wells from large solution
openings in karst
areas of Pulaski County. 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 200
gallons per minute occur at or near stream level or near contact with the underlying
St. Louis limestone.
St. Louis Limestone (Mgl)
Topography
Thick limestone beds in the St. Louis form ledges and cliffs. 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
yields are inadequate for
domestic supply. 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 500 gallons per minute. The lower part of the formation is
composed of siltstone and
argillaceous limestone. Yields from these sedimentary rocks are low
and generally are not
adequate for a domestic supply with bailer or bucket.
Salem and Warsaw Formations (Msh)
Topography
These formations underlies moderately to highly dissected rolling uplands.
In some areas
numerous small sinkholes occur in the Warsaw.
Hydrology
These formations yields enough water for a domestic supply where they
are dominantly
limestone. 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 generally are less than 5 gallons per minute.
Fort Payne Formation (Mbf)
Topography
The Fort Payne underlies moderately to highly dissected rolling uplands.
It forms “knobs” and
steep bluffs along rivers.
Hydrology
Wells in lowland areas close to streams produce enough water for a domestic
supply. Most wells
obtain water from perched or semi-perched 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
the formation consists predominantly of siltstone, most wells are inadequate
for domestic use
(less than 100 gallons per day). Where the Fort Payne chert crops out in lowland
areas close to streams,
the limestone and chert facies supply enough water for a domestic supply.
Borden Formation (MDbb)
Topography
The Borden forms the main part of Mississippian escarpment, ridges,
and knobs. Shale forms
dissected slopes, massive siltstone forms cliffs, and limestone forms
ledges on shale slopes.
Hydrology
The Borden yields 100 to 500 gallons per day to wells in valley bottoms.
It may yield more than 500 gallons per day to drilled wells in broad
valley bottoms from fractured sandy rocks near streams. It yields almost
no water to wells on hills. Water from wells drilled below stream level
may contain salt, sulfate, or iron less than 100 feet below the level
of the principal valley bottoms. Water from dug wells and small springs
is soft and has a low dissolved-solids content. Water from shale is
soft; from the siltstone, hard; and from the limestone, very hard. Because
much of this formation is soft and silty, it has been well suited to
the construction of dug wells in the past, which generally produce less
than 500 gallons per day and often go dry in late summer and fall. The
New Providence Shale yields little or no water to wells.
New Albany Shale (MDnb)
Topography
The New Albany underlies small round hills near the base of the escarpment.
It underlies broad
flat valleys along major streams.
Hydrology
Generally, the New Albany yields little or no water to wells. Water
is hard and may contain large
amounts of hydrogen sulfide and iron. Small 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.
Cumberland Formation, Leipers Limestone, Catheys Formation (Ocl)
Topography
These rocks form moderate to steep slopes and bluffs near the Cumberland
River. Limestone layers, interbedded with shales, form discontinuous
ledges along hillsides in some areas.
Hydrology
In lowland area bordering large streams, these rocks yield enough water
for a domestic supply (more than 500 gallons per day). Elsewhere they
yield little water to wells, and 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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