|
Alluvium (Qa)
Topography
The alluvium forms extensive floodplains with small terraces along
Rolling Fork, and narrow floodplains and small terraces along Beech
Fork and larger tributaries.
Hydrology
The alluvium yields 100 to more than 500 gallons per day from thick
deposits along Rolling Fork. It 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.
Salem, Harrodsburg Limestones (Msh)
Topography
These limestones underlie gently rolling uplands and tops of some knobs
and the Mississippian Escarpment (Muldraugh Hill) in southwestern Nelson
County. They form steep bluffs above exposures of Borden Formation.
Hydrology
These limestones yield 100 to 500 gallons per day to drilled wells on
broad ridges or on uplands. They yield larger amounts when solution
openings are encountered close to perennial stream level. The limestones
yield water to springs at heads of ravines and on the face of the escarpment.
Wells that encounter large solution openings produce more than 5 gallons
per minute. Water from wells is hard, but otherwise of good quality.
Borden Formation (Muldraugh [Mbf], Halls Gap, Nancy, New Providence
Members [MDbb])
Topography
The Borden is the main part of the Muldraugh Escarpment, ridges, and
knobs. Resistant rocks of the Muldraugh Member cap the escarpment and
larger knobs. Minor limestone beds form ledges and small cliffs. The
New Providence Member underlies the lower, dissected slopes of the knobs
and escarpment and forms broad flat valleys in southern and southwestern
Nelson County. Shale forms steep slopes, and the more resistant siltstone
beds form ledges on slopes and in revines.
Hydrology
The Borden yields 100 to 500 gallons per day to wells in valley bottoms. It
may yield more than 500 gallons per day where thick siltstone beds occur at
and below stream level. It yields almost no water to wells on hills,
but does yield water to small springs in the limestone and siltstone
beds. Water from the shale is soft, from the siltstone, hard, and from
the limestone, very hard. At shallow depths below stream level, water
may contain salt, sulfate, or iron. The silty shale and siltstone are
favorable for dug wells, common in this area. Most dug wells yield less
than 500 gallons per day, and many yield little or go dry in late summer and
early fall. The New Providence yields little or no water to wells.
New Albany Shale (MDnb)
Topography
The New Albany forms broad, flat valleys with steep hillsides, and steep,
dissected bluffs 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 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.
Louisville Limestone (Slw)
Topography
The Louisville Limestone forms prominent outcrops, cliffs, and ledges
in valley sides.
Hydrology
The Louisville yields water to small springs. Water is hard.
Waldron Shale (Slw)
Topography
The Waldron erodes easily, undermining the overlying Louisville Limestone.
Hydrology
The shale yields almost no water to wells or springs. It holds up water
in the overlying Louisville Limestone and prevents recharge to the underlying
Laurel Dolomite. Water is hard.
Laurel Dolomite (Slb)
Topography
The Laurel tops ridges and extensive flat upland surfaces in Nelson
County. It 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 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
The Drakes is somewhat dissected in upland areas, and has moderately
steep slopes where shale predominates, and moderately undulating to
gently rolling surface 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
The Drakes yields 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. It does 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 form gently to moderately rolling uplands away from
major streams, 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, and may yield more than
500 gallons per day from thick limestone beds in the broad valley bottoms.
They yield almost no water to drilled wells on hillsides or ridgetops,
but 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. A 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 has rugged, dissected topography of long, narrow, winding,
steep-sided ridges with narrow, winding, V-shaped valleys of dendritic
drainage pattern. Shales on steep slopes erode easily and are 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
and 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 underling 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 no surface exposure in this county.
Hydrology
The Lexington yields 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 use. It
is not considered a 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 central 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, with high concentrations of dissolved
solids found in many areas. Average reported yields range from 10 to
20 gallons per minute, but are 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.
Previous--Next--Back
to "Groundwater Resources in Kentucky"
|