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Alluvium (Qa)
Topography
Alluvium forms terraces and floodplains along the Rough River and tributaries.
Hydrology
The alluvium may yield as much as 100 gallons per minute from sands
and gravel along the Green and Rough Rivers. Wells along the Rough River
between Taffy and Dundee yield over 10 gallons per minute. Most wells
in thin alluvium furnish less than 100 gallons per day, inadequate for
a domestic supply. Coarse sand and gravel may occur in the alluvium
where rocks of Pennsylvanian age are close to streams. Water is hard.
Tradewater Formation (Pt)
Topography
The Tradewater underlies dissected uplands and ridgetops. Resistant
sandstone beds form cliffs.
Hydrology
The Tradewater generally yields only small quantities of water to wells.
It may yield enough water for a modern domestic supply to wells penetrating
a sufficient thickness of sandstone. Water is fresh near outcrop areas,
but becomes increasingly mineralized with depth. Some wells in the Aberdeen
Sandstone produce over 20 gallons per minute.
Caseyville Formation (Pca)
Topography
The Caseyville underlies rolling uplands. It forms dissected uplands
and ridgetops near the Green River in the southern part of the quadrangle.
Hydrology
Yields of 60 gallons per minute have been obtained from thick sandstone beds. The
Caseyville will yield enough water for a modern domestic supply to most
wells penetrating sandstone. At depth, the water becomes salty or may
have a high sodium bicarbonate content. Electric logs indicate that
moderately mineralized water may be obtained locally from this formation
at depths of 1,200 feet.
Buffalo Wallow Formation, Leitchfield Formation, Tar Springs Sandstone
(Mcu)
Topography
These rocks form gently rolling uplands and fairly steep slopes adjacent
to stream valleys. Sandstone lenses, some massive, form small benches.
Hydrology
These formations yield little or no water.
Glen Dean Limestone, Hardinsburg Sandstone (Mcl)
Topography
These formations underlie gently rolling to level uplands. The uplands
are dissected along the perimeter of the Dripping Springs Escarpment.
Limestone forms steep slopes above benches of the underlying sandstone.
Sandstone forms small discontinuous benches on hillsides.
Hydrology
These formations yield little or no water. Most wells in upland areas
are inadequate for a domestic supply.
Golconda Formation (Haney Limestone, Big Clifty Sandstone, Beech
Creek Limestone Members) (Mcl)
Topography
The Golconda underlies gently rolling to flat uplands. It forms bluffs
near heads of valleys. The Big Clifty Sandstone caps the Dripping Springs
Escarpment, which is several hundred feet high.
Hydrology
Deep wells that penetrate the sandstone formations near perennial stream
level may produce enough for a domestic supply (more than 500 gallons
per day). Close to outcrop areas, particularly near major escarpments,
yields from perched water bodies generally are low and not dependable.
Minor spring horizons occur on discontinuous layers of shale near the
base of the sandstones. The most conspicuous springs are those that
discharge from the base of the Big Clifty Sandstone. These are the “dripping
springs” of the Dripping Springs Escarpment. Many of these springs
go dry during the late fall and summer, and very few are adequate for
a domestic supply. Limestone formations yield small to adequate supplies
from solution openings. In lowland areas bordering streams, some wells
produce enough for a domestic supply. Many springs occur at the base
of the limestones where they crop out on escarpments and hillsides.
Girkin Formation (Reelsville Limestone, Sample Sandstone, Beaver Bend
and Paoli Limestones) (Mcl)
Topography
These rocks form the lower part of the Dripping Springs Escarpment.
The lower part of the formation underlies rolling karst areas near the
base of the escarpment. These rocks contain numerous large sinks into
which the overlying sandstone has collapsed. Upper Mammoth Cave passages
are developed within the lower beds of the Girkin Formation.
Hydrology
Most wells in upland areas are inadequate for domestic use; however,
some wells yield enough water for a domestic supply (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 rolling karst areas.
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. The Ste. Genevieve contains major caverns of the Mammoth Cave area,
which have large connected subsurface streams. 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. Smaller springs discharge from perched
water bodies in the upland area, but many go dry during late summer
and fall.
St. Louis Limestone (Mgl)
Topography
The St. Louis underlies rolling karst areas. It commonly has less relief
than karst in areas underlain by the Ste. Genevieve Limestone, but sinkholes
are steeper.
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 in high areas above perennial streams, yields are often inadequate
for domestic supply. Yields of wells close to major streams are large
where solution openings are penetrated, but most wells near major streams
are inadequate. The St. Louis is a major spring horizon, with many springs
flowing several hundred to several thousand gallons a minute. Many springs
are used for public and industrial water supplies.
The U.S. Geological Survey's Hydrologic Atlas Series, published cooperatively
with the Kentucky Geological Survey, provides hydrologic information
for the entire state. The atlas for the Grayson County is HA-33.
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