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Alluvium (Qa)
Topography
The alluvium forms narrow floodplains and small terraces along Beech
Fork and larger
tributaries.
Hydrology
The alluvium is too thin and fine grained to yield much water along
Beech Fork and the large tributaries. Water is hard and may have a high
iron content.
New Albany Shale (MDnb)
Topography
The New Albany underlies broad, flat valleys with steep hillsides; steep,
dissected bluffs are along streams.
Hydrology
The New Albany yields 100 to 500 gallons per day to drilled wells in
broad valleys and on uplands. It yields water to dug wells almost any
place in the black shale. It also yields water to small springs, which
often go dry during late summer and fall. Water is in fractures that
extend less than 50 feet below the land surface. Water is hard and may
contain salt or hydrogen sulfide.
Laurel Dolomite (Slb)
Topography
The Laurel forms ledges on steep hillsides and in bluffs along streams.
Hydrology
The Laurel yields 100 to 500 gallons per day to drilled wells in valley bottoms,
on broad ridges, and
along streams on uplands. It yields water to many springs. Water is
hard.
Osgood Formation (Slb)
Topography
The Osgood forms steep, dissected hillsides. It erodes easily, undermining
the Laurel.
Hydrology
The Osgood yields almost no water, impedes recharge to the Drakes Formation,
and holds up
water in the Laurel. Limestone yields water to small springs. Water
is hard.
Brassfield Formation (Slb)
Topography
The Brassfield forms ledges on slopes and on the tops of small cliffs.
Hydrology
The Brassfield yields almost no water to wells, but 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 somewhat-dissected upland areas, with moderately
steep slopes where shale predominates, and moderately undulating to
gently rolling surfaces where limestone predominates. Slopes are steep
to cliffy and dissected along large streams; many are littered with
limestone slabs left after shale erodes and washes away. Small sinkholes
with some underground drainage are present where thick limestone beds
occur along broad upland stream valleys.
Hydrology
These formations yield 100 to 500 gallons per day to drilled wells in broad
valleys and along streams on
uplands, but almost no water to drilled wells on hillsides or ridgetops.
They do yield water to
small springs. Water is hard and in valley bottoms may contain salt
or hydrogen sulfide. Shale
prevents circulation of water in thicker limestone beds except where
limestone is exposed on flat
ridges or valley bottoms.
Grant Lake Limestone, Calloway Creek Limestone (Oaf)
Topography
These limestones underlie gently to moderately rolling uplands away
from major streams. They are more highly dissected where shale content
increases, and dissected and steep along large streams. Thick limestone
beds stand out as ledges along steep hillsides and bluffs along streams,
and where present on uplands, they underlie broad, flat valleys that
may have small sinkholes and some underground drainage. The lower part
of the Calloway Creek caps broad, flat ridges between steep-sided valleys
cut into underlying shale of the Clays Ferry Formation.
Hydrology
These limestones yield 100 to 500 gallons per day to drilled wells in
broad valleys and along streams in uplands. They may yield more than
500 gallons per day from thick limestone beds in the broad valley bottoms,
but almost no water to drilled wells on hillsides or ridgetops. They
do yield water to small springs and seeps. A limestone bed 15 feet thick
in the lower part of the Grant Lake Limestone yields as much as 30 gallons
per minute to springs. The sandy zone near the base yields little water.
Water is hard, and in valley bottoms may contain salt or hydrogen sulfide.
Clays Ferry Formation (Okc)
Topography
The Clays Ferry forms rugged, dissected topography of long, narrow,
winding, steep-sided ridges with narrow, winding, V-shaped valleys of
dendritic drainage pattern. Shale on steep slopes erodes easily and
is covered with thin limestone slabs in many places. The contrast with
rolling upland outcrop areas of the overlying Drakes, Grant Lake, and
Calloway Creek formations is striking, except along large streams, where
change is masked by dissection.
Hydrology
The Clays Ferry yields 100 to 500 gallons per day to drilled wells in
large valley bottoms along streams, but almost no water to drilled wells
on hillsides or ridgetops. It may yield some water to dug wells on ridgetops.
It yields water to small springs and seeps. Water is hard, and in valley
bottoms may contain salt or hydrogen sulfide. Shale has small, poorly
connected openings, and groundwater circulation is slow. On ridgetops
the shale impedes downward percolation of water and holds up water in
the soil and weathered-rock zone. Dug wells, having large wall areas,
are best suited for obtaining this water. On broad ridges capped by
the Grant Lake or Calloway Creek formations, the underlying Clays Ferry
holds up a semiperched water body in the Grant Lake and Calloway Creek,
and dug wells produce some water; however, wells often go dry in late
summer and fall.
Lexington Limestone (Ol)
Topography
The Lexington has very limited surface exposure in this county.
Hydrology
The Lexington may yield more than 500 gallons per day to wells in valley bottoms
and 100 to 500
gallons per day to wells in small valleys. Water is hard and may contain salt
or hydrogen sulfide in some
places.
High Bridge Group (Ohb)
Topography
The High Bridge has no surface exposure in this county, but underlies
the entire area.
Hydrology
The High Bridge is not likely to yield usable amounts for any purpose.
It is not considered an
aquifer in this area.
Knox Group (Okx)
Topography
The Knox has no surface exposure in Kentucky, but underlies the entire
state at varying depths.
Hydrology
In the Inner Bluegrass Region of Kentucky, fresh water has been found
in the upper 100 to 250 feet of this largely untested dolomite-rich
aquifer. Wells often exceed 750 feet in total depth, and have high concentrations
of dissolved solids in many areas. Average reported yields range in
the 10 to 20 gallons per minute range but can be as high as 75 gallons
per minute.
You can find out more about the Knox
aquifer.
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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