New Albany Shale (MDnb)
The New Albany forms broad, flat valleys and flat upland surfaces. It
forms steep, dissected hillsides and bluffs along streams.
The New Albany yields 100 to 500 gallons per day to drilled wells in valley
bottoms and on uplands, usually at depths of less than 50 feet. Water
from depths greater than 50 feet is highly mineralized. The New Albany
yields water to small springs. Water may be soft or highly mineralized.
Salt, hydrogen sulfide, and iron are the usual objectionable constituents.
Crab Orchard Formation and Brassfield Dolomite (Scb)
The 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
The shale yields almost no water to wells or springs, but may yield
small amounts of water to wells in valley bottoms. Water is highly mineralized.
Dolomite beds yield hard water to small springs.
Drakes Formation (Od)
The Drakes forms dissected upland areas, with slopes moderately steep
where underlain by shale, and moderately undulating to gently rolling
where underlain by limestone. It forms steep and cliffy slopes along
large streams, littered with limestone slabs left as shale beds weather
and wash away.
The Drakes yields 100 to 500 gallons per day to drilled wells in broad valleys
and along streams in upland, 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 limits amount of water that has access to thick limestone beds,
and therefore restricts number of openings in these beds enlarged by
solution. As a result, the limestone beds yield little water.
Ashlock Formation and Calloway Creek Limestone (Oaf)
These formations create gently to moderately rolling uplands away from
major streams, more highly dissected where shale content increases.
Small sinkholes, minor underground drainage, and broad, flat valleys
occur where limestone predominates.
These rocks yield 100 to 500 gallons per day to drilled wells in broad valleys
and along streams in 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.
Where thick limestone beds with little shale occur below stream level
in valley bottoms or on uplands, they may have undergone solutional
enlargement of fractures and bedding-plane openings. Wells drilled into
these limestone beds may produce more than 500 gallons per day. These thick
beds also yield water to some large springs.
Garrard Siltstone (Okc)
The Garrard forms prominent ledges along hillsides.
The Garrard yields 100 to 500 gallons per day to drilled wells in valley bottoms,
but almost no water to wells on hillsides or ridgetops. It yields little
water to springs. The well-cemented siltstone and fine-grained sandstone
and siltstone do not provide many openings for water and yields almost
no water to wells. Water is hard.
Clays Ferry Formation and Kope Formation (Okc)
These rocks form a rugged topography of narrow, steep-sided ridges with
narrow V-shaped valleys of dendritic drainage. Steep slopes erode easily
and are covered with thin limestone slabs in many places. In the lower
part of the formation topography becomes more gently to moderately rolling
uplands with small sinkholes and some underground drainage where limestone
These formations yield 100 gallons per day to drilled wells in valley bottoms,
but almost no water to drilled wells on hillsides or ridgetops. They
do yield water to small springs and seeps. In the lower, limestone rich
section, drilled wells can yield 100 to 500 gallons per day in valley bottoms
along streams. Water is hard in valley bottoms may contain salt or hydrogen
sulfide. Shale has small, poorly-connected openings, and ground-water
circulation is slow; as a result, little water is available to wells
and springs. On ridgetops the shale prevents downward percolation of
water, and creates small semiperched water bodies in lower part of soil
and upper part of weathered bedrock.
Upper Part of Lexington Limestone (Tanglewood Limestone, Millersburg,
Devils Hollow, Sulfur Well, Brannon and Perryville Members) (Ol)
The Upper Lexington forms broad flat valleys in uplands. Where dominantly
limestone, the Upper Lexington has well-developed subsurface drainage
and many sinkholes, with gently sloping hillsides adjacent to small
streams in uplands. The resistant shale and soft bentonite-rich beds
form a subdued benchlike topography along hillsides and streams.
The Upper Lexington yields more than 500 gallons per day to wells in valley
bottoms and along streams in uplands. It yields 100 to 500 gallons per day to
many perennial springs, and more than 100 gallons per minute to a few large springs.
The amount of water available in rocks of the Lexington Limestone is
dependent on the amount of shale. Generally, throughout the whole Lexington
Limestone section, the more shale found within the zone of interest,
the less water will be found. Yields water to springs from resistant
Brannon Member. Water is hard and may contain salt or hydrogen sulfide
in some places. Water from wells near fault zones may contain objectionable
amounts of salt.
Lower Part of Lexington Limestone (Grier, Logana and Curdsville Members)
These limestones form rolling to dissected uplands. Sinkholes are very
common; the large ones occur in the Grier Limestone. Underground drainage
is well developed. Natural outcrops are rare in the rolling upland,
but the limestone beneath hill slopes is evident from the benchlike
or terrace like appearance of the slopes. Limestone crops out in discontinuous
bands in the valley sides in the dissected part near the Kentucky River.
The lower Lexington yields more than 500 gallons per day to wells in valley
bottoms and along streams in uplands. In the Curdsville along large
streams yields are up to 150 gallons per minute from thick limestone beds. The
limestones yield water to many small and large springs. The amount of
water available in rocks of the Lexington Limestone is dependent on
the amount of shale. Generally, the upper part of the Lexington Limestone
contains more shale and yields less water in contrast to the lower part
which is mostly limestone in many places. Water is hard and may contain
salt or hydrogen sulfide in some places. Water from wells near fault
zones may contain objectionable amounts of salt.
High Bridge Group ( Tyrone Limestone, Oregon Formation, Camp Nelson
The High Bridge forms steep slopes and high cliffs along the Kentucky
River and lower parts of tributaries. The Camp Nelson limestone forms
flat terraces with occasional sinkholes in the bottom of the Kentucky
River gorge and steep cliffs along the lower sides. It also extends
up the large tributaries, forming flat bottoms and steep walls. The
Oregon crops out in a band in the walls of the gorge and up a few large
tributaries. The Tyrone crops out in the upper walls of the Kentucky
River gorge and extends up the large tributaries nearly to the upland,
forming broad, flat valleys with sinkholes and underground drainage.
These limestones yield 100 to more than 500 gallons per day to drilled wells
in valleys of the Kentucky River and large tributaries. Yields have
been reported as much as 225 gallons per minute to wells drilled into the Camp
Nelson limestone adjacent to the Kentucky River, from solution channels
and fractures connected with the river. The limestones also yield water
to springs on hillsides and in steep walls along large streams. Water
is hard and may contain hydrogen sulfide but generally of good quality.
Wells drilled into the Highbridge through overlying rocks produce almost
no water because bentonite beds in the Tyrone prevent recharge to underlying
rocks except where the bentonite has been breached or removed by erosion.
Knox Group (Okx)
The Knox has no surface exposure in Kentucky, but underlies the entire
state at varying depths.
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 with high concentrations
of dissolved solids found in many areas. Average reported yields range
in the 10 to 20 gallons per minute range but as high as 75 gallons per minute.
You can find out more about the Knox
The U.S. Geological Survey's Hydrologic
Atlas Series, published cooperatively with the Kentucky Geological
Survey, provides hydrologic information for the entire state.
to "Groundwater Resources in Kentucky"