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Alluvium (Qa)
Topography
The alluvium forms narrow, discontinuous floodplains and small terraces
along the larger streams.
Hydrology
The alluvium is generally inadequate for a domestic supply, being too
thin and too fine-grained
to yield much water. Water is hard.
Breathitt Group (Pbl) (Pikeville Formation)
Topography
The Breathitt Group underlies the valleys and forms the hills. Tops
of hills and ridges
commonly are capped by sandstone. 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
Corbin (Plc) and Rockcastle (Plr) Sandstone Members, Grundy, Alvy
Creek, and Bee Rock Formations (contains Lee-type sandstone of the former
Lee Formation)
Topography
Thick, resistant sandstones form tops of steep-sided ridges and knobs,
steep bluffs, and cliffs in the eastern part of the county. Some cliff-forming
sandstone paleochannels have been cut through shales of the Paragon
Formation into limestone units of the Upper 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 yields water to a few. Joints and
openings along bedding planes, best developed in sandstone, supply most
of the water to wells. Perched and semiperched water tables are common.
Waters are generally soft or moderately hard and contain noticeable
amounts of iron.
Paragon Formation (Mpn, Mpk)
Topography
The Paragon forms moderate to steep slopes in mountain margin areas
where capped by massive sandstone of the 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 rocks form steep hillsides or underlie broad rolling karst areas
and dissected uplands.
Hydrology
These formations yields more than 500 gallons per day from solution
openings. Some wells produce more than 5 gallons per minute from large
solution openings. Near outcrops areas, particularly near major escarpments,
yields generally are inadequate during dry periods.
Ste. Genevieve Formation (Mgl)
Topography
The Ste. Genevieve underlies dissected karst areas in uplands.
Hydrology
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 the 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 not adequate for a domestic supply with a bailer or
bucket.
Salem and Warsaw Formations (Msh)
Topography
These formations underlie moderately to highly dissected rolling uplands.
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. 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,
and forms 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 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 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 is the main part of the 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; these wells generally produce
less than 500 gallons per day and often go dry in late summer and fall.
New Albany Shale (MDnb)
Topography
The shale forms steep slopes near the base of the eastern mountain margin
escarpment and “knobs.” It underlies small round hills near
base of escarpment, and broad flat valleys along major streams.
Hydrology
The shale generally 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.
Crab Orchard Formation and Brassfield Dolomite (Scb)
Topography
Shale forms steep, dissected hillsides and broad, flat valley bottoms.
It erodes readily below more-resistant overlying limestone, forming
notches and recesses. Dolomite beds form discontinuous ledges along
hillsides.
Hydrology
Shale yields almost no water to wells or springs and is of poor quality.
Water is highly mineralized. Dolomite beds yield hard water of generally
good quality to small springs.
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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