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Alluvium (Qa)
Topography
Alluvial flats are dissected by short, steep-sided gullies near tributaries.
Hydrology
The alluvium is too thin and fine grained to yield large amounts of
water.
Laurel Dolomite (Slb)
Topography
The Laurel forms ledges and cliffs along streams.
Hydrology
The Laurel yields 100 to 500 gallons per day to wells on broad ridges
and along streams, and yields water to small springs at the contact
with the underlying Osgood Formation. Water is hard.
Osgood Formation (Slb)
Topography
The Osgood forms slopes between ledges.
Hydrology
The Osgood yields almost no water from shale, but does yield water to
seeps from limestone. It
impedes recharge to underlying rocks. Water is hard.
Brassfield Formation (Slb)
Topography
The Brassfield forms ledges on slopes and tops of small cliffs of underlying
Saluda limestone.
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 provide moderately dissected upland areas; slopes are
modereately steep where shale predominates and less steep where limestone
predominates. These rocks form steep slopes along large streams and
cliffs; many slopes are dotted with weathered limestone slabs. Solutional
features are evident where thick limestone beds underlie streams.
Hydrology
The Drakes and Bull Fork yield 100 to 500 gallons per day to wells in
large stream valleys, and more where thick limestone is present. They
yield almost no water to wells on hillsides and ridges, except in broad
ridges in the upper part of the formation. They yield water to small
springs. Water is hard and may contain salt in valley bottoms but is
generally of good quality.
Grant Lake Limestone, Fairview Formation, Calloway Creek Limestone
(Oaf)
Topography
These formations provide gently to moderately rolling uplands away from
major streams. They are more highly dissected where shale content increases,
and contain small sinkholes, minor underground drainage, and broad flat
valleys where limestone predominates. The lower part forms broad, flat
ridges between steep-sided valleys cut into underlying shale of the
Kope or Clays Ferry Formations.
Hydrology
These formations yield 100 to 500 gallons per day to drilled wells in
broad valleys and along streams in uplands. They 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
also 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) and Kope Formation (Ok)
Topography
These formations create rugged topography of narrow, steep-sided ridges
with narrow V-shaped valleys of dendritic drainage. Shales on steep
slopes erode easily and are covered with thin limestone slabs in many
places. The contrast with the less-rugged surface of the adjacent areas
is marked, except near major streams. In the lower part of the formation
topography becomes more gently to moderately rolling uplands, with small
sinkholes and some underground drainage where limestone predominates.
Hydrology
These formations 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. They do yield water to small springs
and seeps. Water is hard in valley bottoms and may contain salt or hydrogen
sulfide.
Lexington Limestone (Millersburg Member, Tanglewood Limestone, Sulfur
Well, Brannon,
Grier, Logana Members) (Ol)
Topography
The Lexington Limestone lies in valley bottoms along the large tributaries.
Hydrology
The Lexington Limetone yields more than 500 gallons per day to wells in valley
bottoms and 100 to 500
gallons per day to wells in small valleys. It yields water to springs. 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 Shelby County, but underlies
the entire area.
Hydrology
The High Bridge is not likely to yield usable amounts for any use; 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 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.
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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